How much of the outcome improvement after successful recanalization is explained by follow-up infarct volume reduction?

BACKGROUND

Follow-up infarct volume (FIV) is used as surrogate for treatment efficiency in mechanical thrombectomy (MT). However, previous works suggest that MT-related FIV reduction has only limited association with outcome comparing MT independently of recanalization success versus medical care. It remains unclear to what extent the relationship between successful recanalization versus persistent occlusion and functional outcome is explained by FIV reduction.

OBJECTIVE

To determine whether FIV mediates the relationship between successful recanalization and functional outcome.

METHODS

All patients from our institution enrolled in the German Stroke Registry (May 2015-December 2019) with anterior circulation stroke; availability of the relevant clinical data, and follow-up-CT were analyzed. The effect of FIV reduction on functional outcome (90-day modified Rankin Scale (mRS) score ≤2) after successful recanalization (Thrombolysis in Cerebral Infarction ≥2b) was quantified using mediation analysis.

RESULTS

429 patients were included, of whom, 309 (72 %) had successful recanalization and 127 (39%) had good functional outcome. Good outcome was associated with age (OR=0.89, P<0.001), pre-stroke mRS score (OR=0.38, P<0.001), FIV (OR=0.98, P<0.001), hypertension (OR=2.08, P<0.05), and successful recanalization (OR=3.57, P<0.01). Using linear regression in the mediator pathway, FIV was associated with Alberta Stroke program Early CT Score (coefficient (Co)=-26.13, P<0.001), admission National Institutes of Health Stroke Scale score (Co=3.69, P<0.001), age (Co=-1.18, P<0.05), and successful recanalization (Co=-85.22, P<0.001). Successful recanalization increased the probability of good outcome by 23 percentage points (pp) (95% CI 16pp to 29pp). 56% (95% CI 38% to 78%) of the improvement in good outcome was explained by FIV reduction.

CONCLUSION

56% (95% CI 38% to 78%) of outcome improvement after successful recanalization was explained by FIV reduction. Results corroborate pathophysiological assumptions and confirm the value of FIV as an imaging endpoint in clinical trials. 44% (95% CI 22% to 62%) of the improvement in outcome was not explained by FIV reduction and reflects the remaining mismatch between radiological and clinical outcome measures.

Prognostic value of recanalization attempts in endovascular therapy for M2 segment middle cerebral artery occlusions

BACKGROUND

There is growing evidence suggesting efficacy of endovascular therapy for M2 occlusions of the middle cerebral artery. More than one recanalization attempt is often required to achieve successful reperfusion in M2 occlusions, associated with general concerns about the safety of multiple maneuvers in these medium vessel occlusions.

AIM

The aim of this study was to investigate the association between the number of recanalization attempts and functional outcomes in M2 occlusions in comparison with large vessel occlusions (LVO).

METHODS

Retrospective multicenter cohort study of patients who underwent endovascular therapy for primary M2 occlusions. Patients were enrolled in the German Stroke Registry at 1 of 25 comprehensive stroke centers between 2015 and 2021. The study cohort was subdivided into patients with unsuccessful reperfusion (mTICI 0-2a) and successful reperfusion (mTICI 2b-3) at first, second, third, fourth, or ⩾fifth recanalization attempt. Primary outcome was 90-day functional independence defined as modified Rankin Scale score of 0-2. Safety outcome was the occurrence of symptomatic intracranial hemorrhage. Internal carotid artery or M1 occlusions were defined as LVO and served as comparison group.

RESULTS

A total of 1078 patients with M2 occlusion were included. Successful reperfusion was observed in 87.1% and 90-day functional independence in 51.9%. The rate of functional independence decreased gradually with increasing number of recanalization attempts (p < 0.001). In both M2 occlusions and LVO, successful reperfusion within three attempts was associated with greater odds of functional independence, while success at ⩾fourth attempt was not. Patients with ⩾4 attempts exhibited higher rates of symptomatic intracranial hemorrhage in M2 occlusions (6.5% vs 2.7%, p = 0.02) and LVO (7.2% vs 3.5%, p < 0.001).

CONCLUSION

This study suggests a clinical benefit of successful reperfusion within three recanalization attempts in endovascular therapy for M2 occlusions, which was similar in LVO. Our findings reduce concerns about the risk-benefit ratio of multiple attempts in M2 medium vessel occlusions.

DATA ACCESS STATEMENT

The data that support the findings of this study are available on reasonable request after approval of the German Stroke Registry (GSR) steering committee.

CLINICAL TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT03356392.

Effect of short- versus long-term serum glucose levels on early ischemic water homeostasis and functional outcome in patients with large vessel occlusion stroke

BACKGROUND AND PURPOSE

In ischemic stroke, the impact of short- versus long-term blood glucose level (BGL) on early lesion pathophysiology and functional outcome has not been assessed. The purpose of this study was to directly compare the effect of long-term blood glucose (glycated hemoglobin [HbA1c]) versus serum BGL on early edema formation and functional outcome.

METHODS

Anterior circulation ischemic stroke patients who underwent mechanical thrombectomy after multimodal computed tomography (CT) on admission were analyzed. Endpoints were early ischemic cerebral edema, measured by quantitative net water uptake (NWU) on initial CT and functional independence at Day 90.

RESULTS

A total of 345 patients were included. Patients with functional independence had significantly lower baseline NWU (3.1% vs. 8.3%; p < 0.001) and lower BGL (113 vs. 123 mg/dL; p < 0.001) than those without functional independence, while HbA1c levels did not differ significantly (5.7% vs. 5.8%; p = 0.15). A significant association was found for NWU and BGL (ß = 0.02, 95% confidence interval [CI] 0.006-0.03; p = 0.002), but not for HbA1c and NWU (ß = -0.16, 95% CI -0.53-0.21; p = 0.39). Mediation analysis showed that 67% of the effect of BGL on functional outcome was mediated by early edema formation.

CONCLUSION

Aggravated early edema and worse functional outcome was associated with elevated short-term serum BGL, but not with HbA1c levels. Hence, the link between short-term BGL and early edema development might be used as a target for adjuvant therapy in patients with ischemic stroke.

Early neurological deterioration in patients with acute ischemic stroke is linked to unfavorable cerebral venous outflow

INTRODUCTION

Early neurological deterioration (END) is associated with poor outcomes in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). Causes of END after mechanical thrombectomy (MT) include unsuccessful recanalization and reperfusion hemorrhages. However, little is known about END excluding the aforementioned causes. We aimed to investigate factors associated with unexplained END (ENDunexplained) with regard to the cerebral collateral status.

PATIENTS AND METHODS

Multicenter retrospective study of AIS-LVO patients with successful MT (mTICI 2b-3). On admission CT angiography (CTA), pial arterial collaterals and venous outflow (VO) were assessed using the modified Tan-Scale and the Cortical Vein Opacification Score (COVES), respectively. ENDunexplained was defined as an increase in NIHSS score of ⩾ 4 within the first 24 hours after MT without parenchymal hemorrhage on follow-up imaging. Multivariable regression analyses were performed to examine factors of ENDunexplained and unfavorable functional outcome (modified Rankin Scale score 3-6).

RESULTS

A total of 620 patients met the inclusion criteria. ENDunexplained occurred in 10% of patients. While there was no significant difference in pial arterial collaterals, patients with ENDunexplained exhibited more often unfavorable VO (81% vs. 53%; P < 0.001). Unfavorable VO (aOR [95% CI]; 2.56 [1.02-6.40]; P = 0.045) was an independent predictor of ENDunexplained. ENDunexplained was independently associated with unfavorable functional outcomes at 90 days (aOR [95% CI]; 6.25 [2.06-18.94]; P = 0.001).

DISCUSSION AND CONCLUSION

Unfavorable VO on admission CTA was associated with ENDunexplained. ENDunexplained was independently linked to unfavorable functional outcomes at 90 days. Identifying AIS-LVO patients at risk of ENDunexplained may help to select patients for intensified monitoring and guide to optimal treatment regimes.

Quantification of ischemic brain edema after mechanical thrombectomy using dual-energy computed tomography in patients with ischemic stroke

Net water uptake (NWU) is a quantitative imaging biomarker used to assess cerebral edema resulting from ischemia via Computed Tomography (CT)-densitometry. It serves as a strong predictor of clinical outcome. Nevertheless, NWU measurements on follow-up CT scans after mechanical thrombectomy (MT) can be affected by contrast staining. To improve the accuracy of edema estimation, virtual non-contrast images (VNC-I) from dual-energy CT scans (DECT) were compared to conventional polychromatic CT images (CP-I) in this study. We examined NWU measurements derived from VNC-I and CP-I to assess their agreement and predictive value in clinical outcome. 88 consecutive patients who received DECT as follow-up after MT were included. NWU was quantified on CP-I (cNWU) and VNC-I (vNWU). The clinical endpoint was functional independence at discharge. cNWU and vNWU were highly correlated (r = 0.71, p < 0.0001). The median difference between cNWU and vNWU was 8.7% (IQR: 4.5-14.1%), associated with successful vessel recanalization (mTICI2b-3) (ß: 11.6%, 95% CI 2.9-23.0%, p = 0.04), and age (ß: 4.2%, 95% CI 1.3-7.0%, p = 0.005). The diagnostic accuracy to classify outcome between cNWU and vNWU was similar (AUC:0.78 versus 0.77). Although there was an 8.7% median difference, indicating potential edema underestimation on CP-I, it did not have short-term clinical implications.

Penumbra salvage in extensive stroke: exploring limits for reperfusion therapy

BACKGROUND

The effect of thrombectomy in patients presenting with extensive ischemic stroke at baseline is currently being investigated; it remains uncertain to what extent brain tissue may be saved by reperfusion in such patients. Penumbra salvage volume (PSV) has been described as a tool to measure the volume of rescued penumbra.

OBJECTIVE

To assess whether the effect of recanalization on PSV is dependent on the extent of early ischemic changes.

METHODS

Observational study of patients with anterior circulation ischemic stroke triaged by multimodal-CT undergoing thrombectomy. PSV was defined as the difference between baseline penumbra volume and net infarct growth to follow-up. The effect of vessel recanalization on PSV depending on the extent of early ischemic changes (defined using Alberta Stroke Program Early CT Score (ASPECTS) and core volumes based on relative cerebral blood flow) was determined using multivariable linear regression analysis, and the association with functional outcome at day 90 was tested using multivariable logistic regression.

RESULTS

384 patients were included, of whom 292 (76%) achieved successful recanalization (modified Thrombolysis in Cerebral Infarction ≥2b). Successful recanalization was independently associated with 59 mL PSV (95% CI 29.8 to 88.8 mL) and was linked to increased penumbra salvage up to an ASPECTS of 3 and core volume up to 110 mL. Recanalization was associated with a higher probability of a modified Rankin Scale score of ≤2 up to a core volume of 100 mL.

CONCLUSIONS

Recanalization was associated with significant penumbra salvage up to a lower ASPECTS margin of 3 and upper core volume margin of 110 mL. The clinical benefit of recanalization for patients with very large ischemic regions of >100 mL or ASPECTS <3 remains uncertain and requires prospective investigation.

Thrombectomy in M2 occlusion compared to M1 occlusion: treatment effects of Thrombolysis In Cerebral Infarction (TICI) 2b and TICI 3 recanalization on functional outcome

BACKGROUND

Emerging data suggest that mechanical thrombectomy (MT) might also be safe and efficient for medium and distal occlusions. This study aims to compare average treatment effects on functional outcome of different degrees of recanalization after MT in patients with M2 occlusion and M1 occlusion.

METHODS

All patients enrolled in the German Stroke Registry (GSR) between June 2015 and December 2021 were analyzed. Inclusion criteria were stroke with primary M1 occlusion or M2 occlusion, and availability of relevant clinical data. 4259 patients were included, thereof 1353 with M2 occlusion and 2906 with M1 occlusion. Treatment effects were analyzed using double-robust inverse-probability-weighted regression-adjustment (IPWRA) estimators to control for confounding covariates. Binarized endpoint metrics were defined as good outcome with modified Rankin Scale (mRS) ≤2 at 90 days, and linearized endpoint metrics were defined as mRS shift pre-stroke to 90 days. Effects were evaluated for near complete recanalization (Thrombolysis In Cerebral Infarction scale (TICI) 2b) and complete recanalization (TICI 3).

RESULTS

Treatment effect estimation for TICI ≥2b versus TICI <2b in M2 occlusions showed an increase in the probability of a good outcome from 27% to 47% with a number-needed-to-treat (NNT) of 5. For M1 occlusions the probability of a good outcome increased from 16% to 38% with NNT 4.5. TICI 3 versus TICI 2b increased the probability of a good outcome by 7 percentage points in M1 occlusions; for M2 occlusions the beneficial effect was not significant.

CONCLUSIONS

Results suggest that successful recanalization with TICI ≥2b versus TICI <2b after MT in M2 occlusions provides significant patient benefit with treatment effects comparable to M1 occlusions. The probability of functional independence increased by 20 percentage points (NNT 5) and stroke-related mRS increase was reduced by 0.9 mRS points. In contrast to M1 occlusions, complete recanalization TICI 3 versus TICI 2b had lower additional beneficial effect.

Brain edema growth after thrombectomy is associated with comprehensive collateral blood flow

BACKGROUND

We determined whether a comprehensive assessment of cerebral collateral blood flow is associated with ischemic lesion edema growth in patients successfully treated by thrombectomy.

METHODS

This was a multicenter retrospective study of ischemic stroke patients who underwent thrombectomy treatment of large vessel occlusions. Collateral status was determined using the cerebral collateral cascade (CCC) model, which comprises three components: arterial collaterals (Tan Scale) and venous outflow profiles (Cortical Vein Opacification Score) on CT angiography, and tissue-level collaterals (hypoperfusion intensity ratio) on CT perfusion. Quantitative ischemic lesion net water uptake (NWU) was used to determine edema growth between admission and follow-up non-contrast head CT (ΔNWU). Three groups were defined: CCC+ (good pial collaterals, tissue-level collaterals, and venous outflow), CCC- (poor pial collaterals, tissue-level collaterals, and venous outflow), and CCCmixed (remainder of patients). Primary outcome was ischemic lesion edema growth (ΔNWU). Multivariable regression models were used to assess the primary and secondary outcomes.

RESULTS

538 patients were included. 157 patients had CCC+, 274 patients CCCmixed, and 107 patients CCC- profiles. Multivariable regression analysis showed that compared with patients with CCC+ profiles, CCC- (β 1.99, 95% CI 0.68 to 3.30, P=0.003) and CCC mixed (β 1.65, 95% CI 0.75 to 2.56, P<0.001) profiles were associated with greater ischemic lesion edema growth (ΔNWU) after successful thrombectomy treatment. ΔNWU (OR 0.74, 95% CI 0.68 to 0.8, P<0.001) and CCC+ (OR 13.39, 95% CI 4.88 to 36.76, P<0.001) were independently associated with functional independence.

CONCLUSION

A comprehensive assessment of cerebral collaterals using the CCC model is strongly associated with edema growth and functional independence in acute stroke patients successfully treated by endovascular thrombectomy.

Predictors of functional outcome after thrombectomy for M2 occlusions: a large scale experience from clinical practice

Mechanical thrombectomy (MT) for acute ischemic stroke with medium vessel occlusions is still a matter of debate. We sought to identify factors associated with clinical outcome after MT for M2-occlusions based on data from the German Stroke Registry-Endovascular Treatment (GSR-ET). All patients prospectively enrolled in the GSR-ET from 05/2015 to 12/2021 were analyzed (NCT03356392). Inclusion criteria were primary M2-occlusions and availability of relevant clinical data. Factors associated with excellent/good outcome (modified Rankin scale mRS 0-1/0-2), poor outcome/death (mRS 5-6) and mRS-increase pre-stroke to day 90 were determined in multivariable logistic regression. 1348 patients were included. 1128(84%) had successful recanalization, 595(44%) achieved good outcome, 402 (30%) had poor outcome. Successful recanalization (odds ratio [OR] 4.27 [95% confidence interval 3.12-5.91], p < 0.001), higher Alberta stroke program early CT score (OR 1.25 [1.18-1.32], p < 0.001) and i.v. thrombolysis (OR 1.28 [1.07-1.54], p < 0.01) increased probability of good outcome, while age (OR 0.95 [0.94-0.95], p < 0.001), higher pre-stroke-mRS (OR 0.36 [0.31-0.40], p < 0.001), higher baseline NIHSS (OR 0.89 [0.88-0.91], p < 0.001), diabetes (OR 0.52 [0.42-0.64], p < 0.001), higher number of passes (OR 0.75 [0.70-0.80], p < 0.001) and intracranial hemorrhage (OR 0.26 [0.14-0.46], p < 0.001) decreased the probability of good outcome. Additional predictors of mRS-increase pre-stroke to 90d were dissections, perforations (OR 1.59 [1.11-2.29], p < 0.05) and clot migration, embolization (OR 1.67 [1.21-2.30], p < 0.01). Corresponding to large-vessel-occlusions, younger age, low pre-stroke-mRS, low severity of acute clinical disability, i.v. thrombolysis and successful recanalization were associated with good outcome while diabetes and higher number of passes decreased probability of good outcome after MT in M2 occlusions. Treatment related complications increased probability of mRS increase pre-stroke to 90d.

The negative effect of aging on cerebral venous outflow in acute ischemic stroke

Cortical venous outflow (VO) represents an imaging biomarker of increasing interest in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). We conducted a retrospective multicenter cohort study to investigate the effect of aging on VO. A total of 784 patients met the inclusion criteria. Cortical Vein Opacification Score (COVES) was used to assess VO profiles on admission CT angiography. Cerebral microperfusion was determined using the hypoperfusion intensity ratio (HIR) derived from perfusion imaging. Arterial collaterals were assessed using the Tan scale. Multivariable regression analysis was performed to identify independent determinants of VO, HIR and arterial collaterals. In multivariable regression, higher age correlated with worse VO (adjusted odds ratio [95% CI]; 0.83 [0.73-0.95]; P = 0.006) and poorer HIR (β coefficient [95% CI], 0.014 [0.005-0.024]; P = 0.002). The negative effect of higher age on VO was mediated by the extent of HIR (17.3%). We conclude that higher age was associated with worse VO in AIS-LVO, partially explained by the extent of HIR reflecting cerebral microperfusion. Our study underlines the need to assess collateral blood flow beyond the arterial system and provides valuable insights into deteriorated cerebral blood supply in elderly AIS-LVO patients.

Comparison of Thrombolysis In Cerebral Infarction (TICI) 2b and TICI 3 reperfusion in endovascular therapy for large ischemic anterior circulation strokes

BACKGROUND

Landmark thrombectomy trials have provided evidence that selected patients with large ischemic stroke benefit from successful endovascular therapy, commonly defined as incomplete (modified Thrombolysis In Cerebral Infarction (mTICI) 2b) or complete reperfusion (mTICI 3). We aimed to investigate whether mTICI 3 improves functional outcomes compared with mTICI 2b in large ischemic strokes.

METHODS

This retrospective multicenter cohort study was conducted to compare mTICI 2b versus mTICI 3 in large ischemic strokes in the anterior circulation. Patients enrolled in the German Stroke Registry between 2015-2021 were analyzed. Large ischemic stroke was defined as an Alberta Stroke Program Early CT Score (ASPECTS) of 3-5. Patients were matched by final mTICI grade using propensity score matching. Primary outcome was the 90-day modified Rankin Scale (mRS) score.

RESULTS

After matching, 226 patients were included. Baseline and imaging characteristics were balanced between mTICI 2b and mTICI 3 patients. There was no shift on the mRS favoring mTICI 3 compared with mTICI 2b in large ischemic strokes (adjusted common odds ratio (acOR) 1.12, 95% confidence interval (95% CI) 0.64 to 1.94, P=0.70). The rate of symptomatic intracranial hemorrhage was higher in mTICI 2b than in mTICI 3 patients (12.6% vs 4.5%, P=0.03). Mortality at 90 days did not differ between mTICI 3 and mTICI 2b (33.6% vs 37.2%; adjusted OR 0.69, 95% CI 0.33 to 1.45, P=0.33).

CONCLUSIONS

In endovascular therapy for large ischemic strokes, mTICI 3 was not associated with better 90-day functional outcomes compared with mTICI 2b. This study suggests that mTICI 2b might be warranted as the final angiographic result, questioning the benefit/risk ratio of additional maneuvers to seek for mTICI 3 in large ischemic strokes.

TRIAL REGISTRATION NUMBER

NCT03356392.

Edema Reduction versus Penumbra Salvage: Investigating Treatment Effects of Mechanical Thrombectomy in Ischemic Stroke

OBJECTIVE

Mechanical thrombectomy (MT) is of benefit to patients with ischemic stroke; however, the effect of recanalization on lesion pathophysiology is not yet well understood. The aim of this study was to quantitatively assess how the effect of vessel recanalization on clinical outcome is mediated by edema reduction versus penumbra salvage.

METHODS

Consecutive analysis was made of anterior circulation ischemic stroke patients triaged by multimodal computed tomography (CT) undergoing MT. Edema reduction was defined using the difference of quantitative net water uptake (NWU) determined on baseline and follow-up CT (∆NWU). Penumbra salvage volume (PSV) was defined as the difference between admission penumbra and net infarct growth volumes to follow-up. Mediation analyses were performed with vessel recanalization as independent variable (modified Thrombolysis in Cerebral Infarction ≥ 2b) and ∆NWU/PSV as mediator variables. Modified Rankin Scale scores at 90 days served as endpoint.

RESULTS

Of 422 included patients, 321 (76%) achieved successful recanalization. The median ∆NWU was 6.8% (interquartile range [IQR] = 3.9-10.4), and the median PSV was 66ml (IQR = 8-124). ∆NWU, PSV, and recanalization were significantly associated with functional outcome in logistic regression analysis. ∆NWU and PSV partially mediated the relationship between recanalization and outcome. Sixty-six percent of the relationship between recanalization and functional outcome could be explained by treatment-induced edema reduction, whereas 22% was mediated by PSV (p < 0.0001).

INTERPRETATION

Compared to penumbra salvage, edema reduction was a stronger mediator of the effect of recanalization on functional outcome. Given the current trials on adjuvant neuroprotectants also targeting ischemic edema formation, combining reperfusion with antiedematous neuroprotectants may have synergistic effects resulting in better outcomes in patients with ischemic stroke. ANN NEUROL 2023.

Haemorrhage after thrombectomy with adjuvant thrombolysis in unknown onset stroke depends on high early lesion water uptake

BACKGROUND AND PURPOSE

In wake-up stroke, CT-based quantitative net water uptake (NWU) might serve as an alternative tool to MRI to guide intravenous thrombolysis with alteplase (IVT). An important complication after IVT is symptomatic intracerebral haemorrhage (sICH). As NWU directly implies ischaemic lesion progression, reflecting blood-brain barrier injury, we hypothesised that NWU predicts sICH in patients who had a ischaemic stroke undergoing thrombectomy with unknown onset.

METHODS

Consecutive analysis of all patients who had unknown onset anterior circulation ischaemic stroke who underwent CT at baseline and endovascular treatment between December 2016 and October 2020. Quantitative NWU was assessed on baseline CT. The primary endpoint was sICH. The association of NWU and other baseline parameters to sICH was investigated using inverse-probability weighting (IPW) analysis.

RESULTS

A total of 88 patients were included, of which 46 patients (52.3%) received IVT. The median NWU was 10.7% (IQR: 5.1-17.7). The proportion of patients with any haemorrhage and sICH were 35.2% and 13.6%. NWU at baseline was significantly higher in patients with sICH (19.1% vs 9.6%, p<0.0001) and the median Alberta Stroke Program Early CT Score (ASPECTS) was lower (5 vs 8, p<0.0001). Following IPW, there was no association between IVT and sICH in unadjusted analysis. However, after adjusting for ASPECTS and NWU, there was a significant association between IVT administration and sICH (14.6%, 95% CI: 3.3% to 25.6%, p<0.01).

CONCLUSION

In patients with ischaemic stroke with unknown onset, the combination of high NWU with IVT is directly linked to higher rates of sICH. Besides ASPECTS for evaluating the extent of the early infarct lesion, quantitative NWU could be used as an imaging biomarker to assess the degree of blood-brain barrier damage in order to predict the risk of sICH in patients with wake up stroke.

Endovascular treatment of acute tandem lesions in patients with mild anterior circulation stroke

BACKGROUND

In patients with mild strokes the risk-benefit ratio of endovascular treatment (EVT) for tandem lesions has yet to be evaluated outside of current guideline recommendations. This study investigates the frequency as well as procedural and safety outcomes in daily clinical practice.

METHODS

Using data from the German Stroke Registry-Endovascular Treatment (GSR-ET) we analyzed patients with anterior circulation stroke due to tandem-lesions and mild deficits. These patients were defined as ≤5 on the National Institutes of Health Stroke Scale (NIHSS). Recanalization was assessed with the modified Thrombolysis in Cerebral Infarction Scale (mTICI). Early neurological and long-term functional outcomes were assessed with the NIHSS change and modified Rankin scale (mRS), respectively. Safety assessment included periprocedural complications and the rate of symptomatic intracerebral hemorrhage (sICH).

RESULTS

A total of 61 patients met the inclusion criteria and were treated endovascularly for tandem lesions. The median age was 68 (IQR:59-76) and 32.9% (20) were female. Patients were admitted to the hospital with a median NIHSS score of 4 (IQR:2-5) and a median Alberta Stroke Programme Early CT Score (ASPECTS) of 9 (IQR:8-10). Successful recanalization (mTICI 2b-3) was observed in 86.9% (53). NIHSS decreased non-significantly (p=0.382) from baseline to two points (IQR:1-9) at discharge. Excellent (mRS≤1) and favorable (mRS≤2) long-term functional outcome at 90-days was 55.8% (29) and 69.2% (36), respectively. Mortality rates at 90-days were 9.6% (5) and sICH occurred in 8.2% (5).

CONCLUSIONS

EVT for tandem lesions in patients with mild anterior circulation stroke appears to be feasible but may lead to increased rates of sICH. Further studies comparing endovascular with best medical treatment (BMT) especially investigating the risk of periprocedural hemorrhagic complications, are needed.

Association Between Recanalization Attempts and Functional Outcome After Thrombectomy for Large Ischemic Stroke

BACKGROUND

Recently, 3 randomized controlled trials provided high-level evidence that patients with large ischemic stroke achieved better functional outcomes after endovascular therapy than with medical care alone. We aimed to investigate whether the clinical benefit of endovascular therapy is associated with the number of recanalization attempts in extensive baseline infarction.

METHODS

This retrospective multicenter study enrolled patients from the German Stroke Registry who underwent endovascular therapy for anterior circulation large vessel occlusion between 2015 and 2021. Large ischemic stroke was defined as an Alberta Stroke Program Early Computed Tomography Score of 3 to 5. The study cohort was divided into patients with unsuccessful reperfusion (Thrombolysis in Cerebral Infarction score, 0-2a) and successful reperfusion (Thrombolysis in Cerebral Infarction score, 2b/3) at attempts 1, 2, 3, or ≥4. The primary outcome was favorable functional outcome defined as modified Rankin Scale score of 0 to 3 at 90 days. Safety outcomes were symptomatic intracranial hemorrhage after 24 hours and death within 90 days. Multivariable logistic regression was used to identify independent determinants of primary and secondary outcomes.

RESULTS

A total of 348 patients met the inclusion criteria. Successful reperfusion was observed in 83.3% and favorable functional outcomes in 36.2%. Successful reperfusion at attempts 1 (adjusted odds ratio, 5.97 [95% CI, 1.71-24.43]; P=0.008) and 2 (adjusted odds ratio, 6.32 [95% CI, 1.73-26.92]; P=0.008) increased the odds of favorable functional outcome, whereas success at attempts 3 or ≥4 did not. Patients with >2 attempts showed higher rates of symptomatic intracranial hemorrhage (12.8% versus 6.5%; P=0.046). Successful reperfusion at any attempt lowered the odds of death compared with unsuccessful reperfusion.

CONCLUSIONS

In patients with large vessel occlusion and Alberta Stroke Program Early Computed Tomography Score of 3 to 5, the clinical benefit of endovascular therapy was linked to the number of recanalization attempts required for successful reperfusion. Our findings encourage to perform at least 2 recanalization attempts to seek for successful reperfusion in large ischemic strokes, while >2 attempts should follow a careful risk-benefit assessment in these highly affected patients.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03356392.

Thrombectomy in ischemic stroke patients with alberta stroke program early computed tomography score 4-5 and 0-3: Factors associated with favorable outcome

OBJECTIVES

Recently published results of the ANGEL-ASPECT and SELECT2 trials suggest that stroke patients presenting with low Alberta Stroke Program Early Computed Tomography Score (ASPECTS) benefit from mechanical thrombectomy. Purpose of this retrospective study was to identify factors that are associated with a favorable outcome in patients with low ASPECTS of 4-5 and 0-3 undergoing mechanical thrombectomy.

MATERIAL AND METHODS

All patients reported in the quality registry of the German Society for Neuroradiology that were treated between 2018 and 2020 were analyzed. Favorable outcome was defined as a National Institute of Health Stroke Scale (NIHSS) score of less than 9 at dismissal. Successful recanalization was defined as Thrombolysis in Cerebral Infarction (mTICI) ≥ 2b. Multivariable logistic regression analyses were performed to assess the association of baseline and treatment variables with favorable outcome.

RESULTS

621 patients were included in the analysis, thereof 495 with ASPECTS 4-5 and 126 with ASPECTS 0-3. In patients with ASPECTS 4-5patients with favorable outcome had less severe neurological symptoms at admission with median NIHSS of 15 vs. 18 (p<0.001), had less often wake-up strokes (44% vs. 81%, p<0.001), received more often iv-lysis (37% vs. 30%, p<0.001), had more often conscious sedation (29% vs. 16%, p<0.001), had a higher rate of successful recanalization (94% vs. 66% and lower times from groin puncture to recanalization. In multivariate regression analysis lower NIHSS at admission (aOR 0.87, CI 0.89-0.91) and successful recanalization (aOR 3.96, CI 2-8.56) were associated with favorable outcome. For ASPECTS 0-3, patients with favorable outcome had lower median NIHSS at admission (16 vs. 18 (p<0.001), lower number of passes (1 vs. 3, p=0.003) and a higher rate of successful recanalization (94% vs. 66%, p<0.001) and lower times from groin puncture to recanalization. In multivariate regression analysis lower NIHSS at admission (aOR 0.87, CI 0.81-0.94) and successful recanalization, (aOR 11.19, CI 3.19-55.53), were associated with favorable outcome.

CONCLUSION

Full recanalization with low groin punction to recanalization times and low number of passes were associated with favorable outcome in patients with low ASPECTS.

Thrombectomy for M2 Occlusions: Predictors of Successful and Futile Recanalization

BACKGROUND

Patient-specific factors associated with successful recanalization in mechanical thrombectomy (MT) have been evaluated for acute ischemic stroke with large vessel occlusion. However, MT for M2 occlusions is still a matter of debate, and predictors of successful and futile recanalization have not been assessed in detail. We sought to identify predictors of recanalization success in patients with M2 occlusions undergoing MT based on large-scale clinical data.

METHODS

All patients prospectively enrolled in the German Stroke Registry (May, 2015 to December, 2021) were screened (N=13 082). Inclusion criteria for the complete case analysis were isolated M2 occlusions. Standard descriptive statistics and multivariable logistic regression analysis were used to identify factors associated with successful recanalization (Thrombolysis in Cerebral Infarction [TICI]≥2b), complete recanalization (TICI=3) and futile recanalization (TICI≥2b with 90-day modified Rankin Scale [mRS] score >2).

RESULTS

One thousand two hundred ninety-four patients were included, thereof 439 (33.9%) with TICI=2b and 643 (49.7%) with TICI=3. Five hundred sixty-nine (44%) patients had good functional outcome (90-day mRS score ≤2). In multivariable logistic regression, general anesthesia (adjusted odds ratio [aOR], 1.47 [95% CI, 1.05-2.09]; P<0.05) was associated with higher probability of TICI≥2b while intraprocedural change from local to general anesthesia (aOR, 0.49 [0.26-0.95]; P<0.05) and higher pre-mRS (aOR, 0.75 [0.67-0.85]; P<0.001) lowered probability of successful recanalization. Futile recanalization was associated with higher age (aOR, 1.05 [1.04-1.07]; P<0.001), higher prestroke mRS (aOR, 3.12 [2.49-3.91]; P<0.001), higher NIHSS at admission (aOR, 1.11 [1.08-1.14]; P<0.001), diabetes (aOR, 1.96 [1.38-2.8]; P<0.001), higher number of passes (aOR, 1.29 [1.14-1.46]; P<0.001), and adverse events (aOR, 1.82 [1.2-2.74]; P<0.01). Higher Alberta Stroke Program Early CT Score (aOR, 0.85 [0.76-0.94]; P<0.01) and IV thrombolysis (aOR, 0.71 [0.52-0.97]; P<0.05) reduced risk of futile recanalization.

CONCLUSIONS

In patients with M2 occlusions, successful recanalization was significantly associated with general anesthesia and low prestroke mRS, while intraprocedural change from conscious sedation to general anesthesia increased risk of unsuccessful recanalization, presumably caused by difficult anatomy and movement of patients in these cases. Futile recanalization was associated with severe prestroke mRS, comorbidity diabetes, number of passes and adverse events during treatment. IV thrombolysis reduced the risk of futile recanalization.

External Validation and Retraining of DeepBleed: The First Open-Source 3D Deep Learning Network for the Segmentation of Spontaneous Intracerebral and Intraventricular Hemorrhage

BACKGROUND

The objective of this study was to assess the performance of the first publicly available automated 3D segmentation for spontaneous intracerebral hemorrhage (ICH) based on a 3D neural network before and after retraining.

METHODS

We performed an independent validation of this model using a multicenter retrospective cohort. Performance metrics were evaluated using the dice score (DSC), sensitivity, and positive predictive values (PPV). We retrained the original model (OM) and assessed the performance via an external validation design. A multivariate linear regression model was used to identify independent variables associated with the model's performance. Agreements in volumetric measurements and segmentation were evaluated using Pearson's correlation coefficients (r) and intraclass correlation coefficients (ICC), respectively. With 1040 patients, the OM had a median DSC, sensitivity, and PPV of 0.84, 0.79, and 0.93, compared to thoseo f 0.83, 0.80, and 0.91 in the retrained model (RM). However, the median DSC for infratentorial ICH was relatively low and improved significantly after retraining, at p < 0.001. ICH volume and location were significantly associated with the DSC, at p < 0.05. The agreement between volumetric measurements (r > 0.90, p > 0.05) and segmentations (ICC ≥ 0.9, p < 0.001) was excellent.

CONCLUSION

The model demonstrated good generalization in an external validation cohort. Location-specific variances improved significantly after retraining. External validation and retraining are important steps to consider before applying deep learning models in new clinical settings.

Association Between Intravenous Thrombolysis and Clinical Outcomes Among Patients With Ischemic Stroke and Unsuccessful Mechanical Reperfusion

Importance

Clinical evidence of the potential treatment benefit of intravenous thrombolysis preceding unsuccessful mechanical thrombectomy (MT) is scarce.

Objective

To determine whether intravenous thrombolysis (IVT) prior to unsuccessful MT improves functional outcomes in patients with acute ischemic stroke.

Design, Setting, and Participants

Patients were enrolled in this retrospective cohort study from the prospective, observational, multicenter German Stroke Registry-Endovascular Treatment between May 1, 2015, and December 31, 2021. This study compared IVT plus MT vs MT alone in patients with acute ischemic stroke due to anterior circulation large-vessel occlusion in whom mechanical reperfusion was unsuccessful. Unsuccessful mechanical reperfusion was defined as failed (final modified Thrombolysis in Cerebral Infarction grade of 0 or 1) or partial (grade 2a). Patients meeting the inclusion criteria were matched by treatment group using 1:1 propensity score matching.

Interventions

Mechanical thrombectomy with or without IVT.

Main Outcomes and Measures

Primary outcome was functional independence at 90 days, defined as a modified Rankin Scale score of 0 to 2. Safety outcomes were the occurrence of symptomatic intracranial hemorrhage and death.

Results

After matching, 746 patients were compared by treatment arms (median age, 78 [IQR, 68-84] years; 438 women [58.7%]). The proportion of patients who were functionally independent at 90 days was 68 of 373 (18.2%) in the IVT plus MT and 42 of 373 (11.3%) in the MT alone group (adjusted odds ratio [AOR], 2.63 [95% CI, 1.41-5.11]; P = .003). There was a shift toward better functional outcomes on the modified Rankin Scale favoring IVT plus MT (adjusted common OR, 1.98 [95% CI, 1.35-2.92]; P < .001). The treatment benefit of IVT was greater in patients with partial reperfusion compared with failed reperfusion. There was no difference in symptomatic intracranial hemorrhages between treatment groups (AOR, 0.71 [95% CI, 0.29-1.81]; P = .45), while the death rate was lower after IVT plus MT (AOR, 0.54 [95% CI, 0.34-0.86]; P = .01).

Conclusions and Relevance

These findings suggest that prior IVT was safe and improved functional outcomes at 90 days. Partial reperfusion was associated with a greater treatment benefit of IVT, indicating a positive interaction between IVT and MT. These results support current guidelines that all eligible patients with stroke should receive IVT before MT and add a new perspective to the debate on noninferiority of combined stroke treatment.

Outcome prediction prior to thrombectomy of the posterior circulation with machine learning

PURPOSE

Various studies have identified prognostic factors for a favorable outcome of endovascular treatment in posterior circulation. We evaluated various machine learning algorithms in their ability to classify between patients with favorable (defined as 0-2 points on the modified Rankin scale [mRS]), unfavorable (mRS 3-6), poor (mRS 5-6), and nonpoor (mRS 0-4) outcomes at dismissal.

METHODS

We retrospectively analyzed data from 415 patients that were treated between 2018 and 2021 from the multicentric DGNR registry. Five models (random forest, support vector machine, k-nearest neighbor, neural network [NN], and generalized linear model [GLM]) were trained with clinical input variables and evaluated with a test dataset of 82 patients. The model with the highest accuracy on the training dataset was defined as the best model.

RESULTS

A total of 132 patients showed poor and 162 patients showed favorable outcome. All baseline variables except sex were highly significantly different between patients with favorable and unfavorable outcomes. The variables NIHSS, the presence of wake-up stroke, the administration of IV-thrombolysis and mRS pretreatment were significantly different between patients with poor and nonpoor outcomes. The best-performing NN achieved a sensitivity of 0.56, a specificity of 0.86 and an area under the curve (AUC) of 0.77 on the test dataset in the classification analysis between favorable and unfavorable outcomes. The best-performing GLM achieved a sensitivity of 0.65, a specificity of 0.91 and an AUC of 0.81 in the classification analysis between poor and nonpoor outcomes.

CONCLUSION

Short-term favorable and poor outcomes in patients with acute ischemic stroke of the posterior circulation can be predicted prior to thrombectomy with moderate sensitivity and high specificity with machine learning models.

Poor venous outflow profiles increase the risk of reperfusion hemorrhage after endovascular treatment

To investigate whether unfavorable cerebral venous outflow (VO) predicts reperfusion hemorrhage after endovascular treatment (EVT), we conducted a retrospective multicenter cohort study of patients with acute ischemic stroke and large vessel occlusion (AIS-LVO). 629 AIS-LVO patients met inclusion criteria. VO profiles were assessed on admission CT angiography using the Cortical Vein Opacification Score (COVES). Unfavorable VO was defined as COVES ≤ 2. Reperfusion hemorrhages on follow-up imaging were subdivided into no hemorrhage (noRH), hemorrhagic infarction (HI) and parenchymal hematoma (PH). Patients with PH and HI less frequently achieved good clinical outcomes defined as 90-day modified Rankin Scale scores of ≤ 2 (PH: 13.6% vs. HI: 24.6% vs. noRH: 44.1%; p < 0.001). The occurrence of HI and PH on follow-up imaging was more likely in patients with unfavorable compared to patients with favorable VO (HI: 25.1% vs. 17.4%, p = 0.023; PH: 18.3% vs. 8.5%; p = <0.001). In multivariable regression analyses, unfavorable VO increased the likelihood of PH (aOR: 1.84; 95% CI: 1.03-3.37, p = 0.044) and HI (aOR: 2.05; 95% CI: 1.25-3.43, p = 0.005), independent of age, sex, admission National Institutes Health Stroke Scale scores and arterial collateral status. We conclude that unfavorable VO was associated with the occurrence of HI and PH, both related to worse clinical outcomes.

Benefit and risk of intravenous alteplase in patients with acute large vessel occlusion stroke and low ASPECTS

BACKGROUND

The benefit of best medical treatment including intravenous alteplase (IVT) before mechanical thrombectomy (MT) in patients with acute ischemic stroke and extensive early ischemic changes on baseline CT remains uncertain. The purpose of this study was to evaluate the benefit of IVT for patients with low ASPECTS (Alberta Stroke Programme Early CT Score) compared with patients with or without MT.

METHODS

This multicenter study pooled consecutive patients with anterior circulation acute stroke and ASPECTS≤5 to analyze the impact of IVT on functional outcome, and to compare bridging IVT with direct MT. Functional endpoints were the rates of good (modified Rankin Scale (mRS) score ≤2) and very poor (mRS ≥5) outcome at day 90. Safety endpoint was the occurrence of symptomatic intracranial hemorrhage (sICH).

RESULTS

429 patients were included. 290 (68%) received IVT and 168 (39%) underwent MT. The rate of good functional outcome was 14.4% (95% CI 7.1% to 21.8%) for patients who received bridging IVT and 24.4% (95% CI 16.5% to 32.2%) for those who underwent direct MT. The rate of sICH was significantly higher in patients with bridging IVT compared with direct MT (17.8% vs 6.4%, p=0.004). In multivariable logistic regression analysis, IVT was significantly associated with very poor outcome (OR 2.22, 95% CI 1.05 to 4.73, p=0.04) and sICH (OR 3.44, 95% CI 1.18 to 10.07, p=0.02). Successful recanalization, age, and ASPECTS were associated with good functional outcome.

CONCLUSIONS

Bridging IVT in patients with low ASPECTS was associated with very poor functional outcome and an increased risk of sICH. The benefit of this treatment should therefore be carefully weighed in such scenarios. Further randomized controlled trials are required to validate our findings.

Hypoperfusion Intensity Ratio Is Correlated With the Risk of Parenchymal Hematoma After Endovascular Stroke Treatment

BACKGROUND

Parenchymal hematoma (PH) is a major complication after endovascular treatment (EVT) for ischemic stroke. The hypoperfusion intensity ratio (HIR) represents a perfusion parameter reflecting arterial collateralization and cerebral microperfusion in ischemic brain tissue. We hypothesized that HIR correlates with the risk of PH after EVT.

METHODS

Retrospective multicenter cohort study of patients with large vessel occlusion who underwent EVT between 2013 and 2021 at one of the 2 comprehensive stroke centers (University Medical Center Hamburg-Eppendorf, Germany and Stanford University School of Medicine, CA). HIR was automatically calculated on computed tomography perfusion studies as the ratio of brain volume with time-to-max (Tmax) delay >10 s over volume with Tmax >6 s. Reperfusion hemorrhages were assessed according to the Heidelberg Bleeding Classification. Primary outcome was PH occurrence (PH+) or absence (PH-) on follow-up imaging. Secondary outcome was good clinical outcome defined as a 90-day modified Rankin Scale score of 0 to 2.

RESULTS

A total of 624 patients met the inclusion criteria. We observed PH in 91 (14.6%) patients after EVT. PH+ patients had higher HIR on admission compared with PH- patients (median, 0.6 versus 0.4; P<0.001). In multivariable regression, higher admission blood glucose (adjusted odds ratio [aOR], 1.08 [95% CI, 1.04-1.13]; P<0.001), extensive baseline infarct defined as Alberta Stroke Program Early CT Score ≤5 (aOR, 2.48 [1.37-4.42]; P=0.002), and higher HIR (aOR, 1.22 [1.09-1.38]; P<0.001) were independent determinants of PH after EVT. Both higher HIR (aOR, 0.83 [0.75-0.92]; P<0.001) and PH on follow-up imaging (aOR, 0.39 [0.18-0.80]; P=0.013) were independently associated with lower odds of achieving good clinical outcome.

CONCLUSIONS

Poorer (higher) HIR on admission perfusion imaging was strongly associated with PH occurrence after EVT. HIR as a surrogate for cerebral microperfusion might reflect tissue vulnerability for reperfusion hemorrhages. This automated and quickly available perfusion parameter might help to assess the need for intensive medical care after EVT.

Low baseline ischemic water uptake is directly related to overestimation of CT perfusion-derived ischemic core volume

Computed-tomography perfusion (CTP) is frequently used to screen acute ischemic stroke (AIS) patients for endovascular treatment (EVT), despite known problems with ischemic "core" overestimation. This potentially leads to the unfair exclusion of patients from EVT. We propose that net water uptake (NWU) can be used in addition to CTP to more accurately assess the extent and/or stage of tissue infarction. Patients treated for AIS between 06/2015 and 07/2020 were retrospectively analyzed. Baseline CTP-derived core volume (pCore) and NWU were determined. Logistic regression tested the relationship between baseline clinical and imaging variables and core-overestimation (primary outcome). The secondary outcomes comprised 90-day functional independence (modified Rankin score) and lesion growth. 284 patients were included. Median NWU was 7.2% (IQR 2.6-12.8). ASPECTS (RR 1.28, 95% CI 1.09-1.51), NWU (RR 0.94, 95% CI 0.89-0.98), onset to recanalization (RR 1.00, 95% CI 0.99-1.00) and imaging (RR 1.00, 95% CI 1.00-1.00) times, and pCore (RR 1.02, 95% CI 1.01-1.02) were significantly associated with core overestimation. Core-overestimation was more likely to occur in patients with large pCores and low NWU at baseline. NWU was significantly correlated with lesion growth. We conclude that NWU can be used as a supplemental tool to CTP during admission imaging to more accurately assess the extent of ischemia, particularly relevant for patients with large CTP-defined cores who would otherwise be excluded from treatment.

Association of Thrombectomy With Functional Outcome for Patients With Ischemic Stroke Who Presented in the Extended Time Window With Extensive Signs of Infarction

IMPORTANCE

Only limited data are available about a potential benefit associated with endovascular treatment (EVT) for patients with ischemic stroke presenting in the extended time window who also show signs of extensive infarction.

OBJECTIVE

To assess the association of recanalization after EVT with functional outcomes for patients with ischemic stroke presenting in the extended time window who also show signs of extensive infarction.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, multicenter cohort study included patients enrolled in the German Stroke Registry-Endovascular Treatment with an Alberta Stroke Program Early CT Score (ASPECTS) of 5 or less who presented between 6 and 24 hours after stroke onset and underwent computed tomography and subsequent EVT between July 1, 2015, and December 31, 2019.

MAIN OUTCOMES AND MEASURES

The primary end point was a modified Rankin Scale (mRS) score of 3 or less at day 90. The association between recanalization (defined as the occurrence of a modified Thrombolysis in Cerebral Infarction Scale score of 2b or 3) and outcome was assessed using logistic regression and inverse probability weighting analysis.

INTERVENTION

Endovascular treatment.

RESULTS

Of 5853 patients, 285 (5%; 146 men [51%]; median age, 73 years [IQR, 62-81 years]) met the inclusion criteria and were analyzed. Of these 285 patients, 79 (27.7%) had an mRS score of 3 or less at day 90. The rate of successful recanalization was 75% (215 of 285) and was independently associated with a higher probability of reaching an mRS score of 3 or less (adjusted odds ratio, 4.39; 95% CI, 1.79-10.72; P < .001). In inverse probability weighting analysis, a modified Thrombolysis in Cerebral Infarction Scale score of 2b or 3 was associated with a 19% increase (95% CI, 9%-29%; P < .001) in the probability for an mRS score of 3 or more. Multivariable logistic regression analysis suggested a significant treatment benefit associated with vessel recanalization in a time window of up to 17.6 hours and ASPECTS of 3 to 5. The rate of secondary symptomatic intracerebral hemorrhage was 6.3% (18 of 285).

CONCLUSIONS AND RELEVANCE

In this cohort study reflecting daily clinical practice, vessel recanalization for patients with a low ASPECTS and extended time window was associated with better functional outcomes in a time window up to 17.6 hours and ASPECTS of 3 to 5. The results of this study encourage current randomized clinical trials to enroll patients with a low ASPECTS, even within the extended time window.

Venous Outflow Profiles Are Linked to Clinical Outcomes in Ischemic Stroke Patients with Extensive Baseline Infarct

Background and Purpose The benefit of endovascular thrombectomy (EVT) treatment is still unclear in stroke patients presenting with extensive baseline infarct. The use of additional imaging biomarkers could improve clinical outcome prediction and individualized EVT selection in this vulnerable cohort. We hypothesized that cerebral venous outflow (VO) may be associated with functional outcomes in patients with low Alberta Stroke Program Early CT Score (ASPECTS).Methods We conducted a retrospective multicenter cohort study of patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). Extensive baseline infarct was defined by an ASPECTS of ≤5 on admission computed tomography (CT). VO profiles were assessed on admission CT angiography using the Cortical Vein Opacification Score (COVES). Favorable VO was defined as COVES ≥3. Multivariable logistic regression was used to determine the association between cerebral VO and good clinical outcomes (90-day modified Rankin Scale score of ≤3).Results A total of 98 patients met the inclusion criteria. Patients with extensive baseline infarct and favorable VO achieved significantly more often good clinical outcomes compared to patients with unfavorable VO (45.5% vs. 10.5%, P<0.001). Higher COVES were strongly associated with good clinical outcomes (odds ratio, 2.17; 95% confidence interval, 1.15 to 4.57; P=0.024), independent of ASPECTS, National Institutes of Health Stroke Scale, and success of EVT.Conclusions Cerebral VO profiles are associated with good clinical outcomes in AIS-LVO patients with extensive baseline infarct. VO profiles could serve as a useful additional imaging biomarker for treatment selection and outcome prediction in low ASPECTS patients.

Impact of relative cerebral blood volume reduction on early neurological improvement in extensive ischemic stroke

PURPOSE

The benefit of endovascular treatment (EVT) for patients with low ASPECTS is yet ambiguous and currently investigated in randomized trials. As a tool for estimation of infarct extent and progression, CT-perfusion might predict early neurological improvement (ENI) after EVT.

OBJECTIVE

We hypothesized that the degree of relative cerebral blood volume (rCBV) reduction is directly associated with ENI in low ASPECTS patients undergoing EVT.

METHODS

Ischemic stroke patients with ASPECTS≤5 who received multimodal-CT and underwent thrombectomy were analyzed. The rCBV reduction was defined as the ratio of CBV measured in the ischemic lesion and contralateral CBV. Complete reperfusion was defined as eTICI 2c-3. Clinical endpoint was early neurological improvement (ENI) at 24-hours defined continuously (NIHSS change from baseline to 24-hours) and binarized (NIHSS at 24-hours≤8).

RESULTS

102 patients were included. Lower rCBV reduction and complete EVT were independently associated with ENI (-11.4 NIHSS points, p=0.04; -7.3 points, p<0.0001, respectively). The effect of complete EVT on ENI was directly linked to the degree of rCBV reduction: the probability for binary ENI was +34.6%, p=0.004 in patients with low rCBV reduction versus +8.2%, p=0.28 in patients with high rCBV reduction.

CONCLUSION

In ischemic stroke with low ASPECTS, ENI was directly linked to the degree of rCBV reduction as a potential indicator of ischemia depth in extensive baseline infarction. Lower rCBV reduction was associated with higher probability of ENI after complete reperfusion suggesting a less pronounced lesion progression despite its large extent and hence, a higher susceptibility to EVT.

Assessment of Irreversible Tissue Injury in Extensive Ischemic Stroke-Potential of Quantitative Cerebral Perfusion

Computed tomography perfusion (CTP) is used as a tool to select ischemic stroke patients for endovascular treatment (EVT) and is currently investigated in the setting of extensive stroke with low Alberta Stroke Program Early CT scores (ASPECTS). The purpose of this study was to perform a comprehensive quantitative analysis of cerebral blood flow within the ischemic lesion compared to threshold-derived core lesion volumes. We hypothesized that the degree of cerebral blood volume (CBV) reduction within the ischemic lesion is predictive of irreversible tissue injury and functional outcome in patients with low ASPECTS. Ischemic stroke patients with an ASPECTS ≤ 5 who received multimodal CT on admission and underwent thrombectomy were analyzed. The ischemic lesion on CTP was identified, and CTP-derived parameters were measured as absolute means within the lesion and relative to the physiological perfusion measured in a contralateral region of interest. The degree of irreversible tissue injury was assessed using quantitative net water uptake (NWU). Functional endpoint was good outcome defined as modified Rankin Scale (mRS) scores 0-3 at day 90. One hundred eleven patients were included. The median core lesion volume was 71 ml (IQR: 25-107), and the median quantitative NWU was 9.5% (IQR: 6-13). Relative CBV (rCBV) reduction and ASPECTS at baseline were independently associated with NWU in multivariable linear regression analysis (ß: 12.4, 95%CI: 6.0-18.9, p < 0.0001) and (ß: - 0.78, 95% CI: - 1.53 to - 0.02; p = 0.045), respectively. Furthermore, rCBV was significantly associated with good outcome in patients with core volumes > 50 ml (OR: 0.16, 95% CI: 0.05-0.49, p = 0.001). Our study shows that rCBV reduction serves as an early surrogate for increase of NWU as a marker of irreversible tissue injury and lesion progression. Thus, the analysis of rCBV reduction within ischemic lesions may add another dimension to acute stroke triage in addition to core volumes or ASPECTS as indicators of the infarct extent and viability.

How Much of the Thrombectomy Related Improvement in Functional Outcome Is Already Apparent at 24 Hours and at Hospital Discharge?

BACKGROUND

Early neurological status has been described as predictor of functional outcome in patients with anterior circulation stroke after mechanical thrombectomy. It remains unclear to what proportion the improvement of functional outcome at day 90 is already apparent at 24 hours and at hospital discharge and how later factors impact outcome.

METHODS

All patients enrolled in the German Stroke Registry (June 2015-December 2019) with anterior circulation stroke and availability of baseline data and neurological status were included. A mediation analysis was conducted to investigate the effect of successful recanalization (Thrombolysis in Cerebral Infarction scale score ≥2b) on good functional outcome (modified Rankin Scale score ≤2 at day 90) with mediation through neurological status (National Institutes of Health Stroke Scale [NIHSS] at 24 hours and at hospital discharge).

RESULTS

Three thousand fifty-seven patients fulfilled the inclusion criteria, thereof 2589 (85%) with successful recanalization and 1180 (39%) with good functional outcome. In a multivariate logistic regression analysis, probability of good outcome was significantly associated with age (odds ratio [95% CI], 0.95 [0.94-0.96]), prestroke modified Rankin Scale (0.48 [0.42-0.55]), admission-NIHSS (0.96 [0.94-0.98]), 24-hour NIHSS (0.83 [0.81-0.84]), diabetes (0.56 [0.43-0.72]), proximal middle cerebral artery occlusions (0.78 [0.62-0.97]), passes (0.88 [0.82-0.95]), Alberta Stroke Program Early CT Score (1.07 [1.00-1.14]), successful recanalization (2.39 [1.68-3.43]), intracerebral hemorrhage (0.51 [0.35-0.73]), and recurrent strokes (0.54 [0.32-0.92]). Mediation analysis showed a 20 percentage points (95% CI' 17-24 percentage points) increase of probability of good functional outcome after successful recanalization. Fifty-four percent (95% CI' 44%-66%) of the improvement in functional outcome was explained by 24-hour NIHSS and 75% (95% CI' 62%-90%) by NIHSS at hospital discharge.

CONCLUSIONS

Fifty-four percent of the improvement in functional outcome after successful recanalization is apparent in NIHSS at 24 hours, 75% in NIHSS at hospital discharge. Other unknown factors not apparent in NIHSS at the 2 time points investigated account for the remaining effect on long term outcome, suggesting, among others, clinical relevance of delayed neurological improvement and deterioration.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03356392.

Effect of Intravenous Alteplase on Functional Outcome and Secondary Injury Volumes in Stroke Patients with Complete Endovascular Recanalization

Intravenous thrombolytic therapy with alteplase (IVT) is a standard of care in ischemic stroke, while recent trials investigating direct endovascular thrombectomy (EVT) approaches showed conflicting results. Yet, the effect of IVT on secondary injury volumes in patients with complete recanalization has not been analyzed. We hypothesized that IVT is associated with worse functional outcome and aggravated secondary injury volumes when administered to patients who subsequently attained complete reperfusion after EVT. Anterior circulation ischemic stroke patients with complete reperfusion after thrombectomy defined as thrombolysis in cerebral infarctions (TICI) scale 3 after thrombectomy admitted between January 2013–January 2021 were analyzed. Primary endpoints were the proportion of patients with functional independence defined as modified Rankin Scale (mRS) score 0–2 at day 90, and secondary injury volumes: Edema volume in follow-up imaging measured using quantitative net water uptake (NWU), and the rate of symptomatic intracerebral hemorrhage (sICH). A total of 219 patients were included and 128 (58%) patients received bridging IVT before thrombectomy. The proportion of patients with functional independence was 28% for patients with bridging IVT, and 34% for patients with direct thrombectomy (p = 0.35). The rate of sICH was significantly higher after bridging IVT (20% versus 7.7%, p = 0.01). Multivariable logistic and linear regression analysis confirmed the independent association of bridging IVT with sICH (aOR: 2.78, 95% CI: 1.02–7.56, p = 0.046), and edema volume (aOR: 8.70, 95% CI: 2.57–14.85, p = 0.006). Bridging IVT was associated with increased edema volume and risk for sICH as secondary injury volumes. The results of this study encourage direct EVT approaches, particularly in patients with higher likelihood of successful EVT.

Posterior circulation collateral flow modifies the effect of thrombectomy on outcome in acute basilar artery occlusion

BACKGROUND

In basilar artery occlusion stroke, the impact of the collateral circulation on infarct progression in the context of endovascular treatment is yet poorly studied.

AIM

This study investigates the impact of the posterior circulation collateral score (PCCS) on functional outcome according to the extent of early ischemic changes and treatment. We hypothesized that the presence of collaterals, quantified by the PCCS, mediates the effect of endovascular treatment on functional outcome in patients with acute basilar artery occlusion.

METHODS

In this multicenter observational study, patients with basilar artery occlusion and admission computed tomography were analyzed. At baseline, Posterior circulation Acute Stroke Prognosis Early Computed Tomography score (pcASPECTS) was assessed and PCCS was quantified using an established 10-point grading system. Logistic regression analyses were performed to identify factors associated with good functional outcome (modified Rankin Scale scores 0-2 at day 90).

RESULTS

A total of 151 patients were included, of which 112 patients (74%) underwent endovascular treatment. In patients with a better PCCS (>5), the rate of good outcome was significantly higher (55% vs. 11%; p = 0.001). After adjusting for PCCS, vessel recanalization was significantly associated with improved functional outcome (aOR: 4.53, 95%CI: 1.25-16.4, p = 0.02), while there was no association between recanalization status and outcome in univariable analysis. Patients with low pcASPECTS generally showed very poor outcomes (mean modified Rankin Scale score 5.3, 95%CI: 4.9-5.8).

CONCLUSION

PCCS modified the effect of recanalization on functional outcome, particularly in patients with less pronounced ischemic changes in admission computed tomography. These results should be validated to improve patient selection for endovascular treatment in basilar artery occlusion, particularly in uncertain indications, or to triage patients at risk for very poor outcomes.

Quantitative Lesion Water Uptake as Stroke Imaging Biomarker: A Tool for Treatment Selection in the Extended Time Window?

BACKGROUND AND PURPOSE

Patients presenting in the extended time window may benefit from mechanical thrombectomy. However, selection for mechanical thrombectomy in this patient group has only been performed using specialized image processing platforms, which are not widely available. We hypothesized that quantitative lesion water uptake calculated in acute stroke computed tomography (CT) may serve as imaging biomarker to estimate ischemic lesion progression and predict clinical outcome in patients undergoing mechanical thrombectomy in the extended time window.

METHODS

All patients with ischemic anterior circulation stroke presenting within 4.5 to 24 hours after symptom onset who received initial multimodal CT between August 2014 and March 2020 and underwent mechanical thrombectomy were analyzed. Quantitative lesion net water uptake was calculated from the admission CT. Prediction of clinical outcome was assessed using univariable receiver operating characteristic curve analysis and logistic regression analyses.

RESULTS

One hundred two patients met the inclusion criteria. In the multivariable logistic regression analysis, net water uptake (odds ratio, 0.78 [95% CI, 0.64-0.95], P=0.01), age (odds ratio, 0.94 [95% CI, 0.88-0.99]; P=0.02), and National Institutes of Health Stroke Scale (odds ratio, 0.88 [95% CI, 0.79-0.99], P=0.03) were significantly and independently associated with favorable outcome (modified Rankin Scale score ≤1), adjusted for degree of recanalization and Alberta Stroke Program Early CT Score. A multivariable predictive model including the above parameters yielded the highest diagnostic ability in the classification of functional outcome, with an area under the curve of 0.88 (sensitivity 92.3%, specificity 82.9%).

CONCLUSIONS

The implementation of quantitative lesion water uptake as imaging biomarker in the diagnosis of patients with ischemic stroke presenting in the extended time window might improve clinical prognosis. Future studies could test this biomarker as complementary or even alternative tool to CT perfusion.

Thrombectomy in Extensive Stroke May Not Be Beneficial and Is Associated With Increased Risk for Hemorrhage

Background and Purpose

This study evaluates the benefit of endovascular treatment (EVT) for patients with extensive baseline stroke compared with best medical treatment.

Methods

This retrospective, multicenter study compares EVT and best medical treatment for computed tomography (CT)–based selection of patients with extensive baseline infarcts (Alberta Stroke Program Early CT Score ≤5) attributed to anterior circulation stroke. Patients were selected from the German Stroke Registry and 3 tertiary stroke centers. Primary functional end points were rates of good (modified Rankin Scale score of ≤3) and very poor outcome (modified Rankin Scale score of ≥5) at 90 days. Secondary safety end point was the occurrence of symptomatic intracerebral hemorrhage. Angiographic outcome was evaluated with the modified Thrombolysis in Cerebral Infarction Scale.

Results

After 1:1 pair matching, a total of 248 patients were compared by treatment arm. Good functional outcome was observed in 27.4% in the EVT group, and in 25% in the best medical treatment group (P=0.665). Advanced age (adjusted odds ratio, 1.08 [95% CI, 1.05–1.10], P<0.001) and symptomatic intracerebral hemorrhage (adjusted odds ratio, 6.35 [95% CI, 2.08–19.35], P<0.001) were independently associated with very poor outcome. Mortality (43.5% versus 28.9%, P=0.025) and symptomatic intracerebral hemorrhage (16.1% versus 5.6%, P=0.008) were significantly higher in the EVT group. The lowest rates of good functional outcome (≈15%) were observed in groups of failed and partial recanalization (modified Thrombolysis in Cerebral Infarction Scale score of 0/1–2a), whereas patients with complete recanalization (modified Thrombolysis in Cerebral Infarction Scale score of 3) with recanalization attempts ≤2 benefitted the most (modified Rankin Scale score of ≤3:42.3%, P=0.074) compared with best medical treatment.

Conclusions

In daily clinical practice, EVT for CT–based selected patients with low Alberta Stroke Program Early CT Score anterior circulation stroke may not be beneficial and is associated with increased risk for hemorrhage and mortality, especially in the elderly. However, first- or second-pass complete recanalization seems to reveal a clinical benefit of EVT highlighting the vulnerability of the low Alberta Stroke Program Early CT Score subgroup.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03356392.

Interaction Effect of Baseline Serum Glucose and Early Ischemic Water Uptake on the Risk of Secondary Hemorrhage After Ischemic Stroke

Background and Purpose: Intracerebral hemorrhage (ICH) after mechanical thrombectomy (MT) for acute ischemic stroke (AIS) remains a major complication and its early prediction is of high relevance. Baseline serum glucose (BGL) is a known predictor of ICH, but its interaction with early ischemic changes remains uncertain. We hypothesized that BGL interacts with the effect of tissue water uptake on the occurrence of ICH. Methods: Three hundred and thirty-six patients with acute ischemic stroke treated with MT were retrospectively analyzed. ICH was diagnosed within 24 h on non-enhanced CT (NECT) and classified according to the Heidelberg Bleeding Classification. Early tissue water homeostasis has been assessed using quantitative lesion net water uptake (NWU) on admission CT. Multivariate logistic regression was used to identify predictors of ICH. Results: One hundred and seven patients fulfilled the inclusion criteria of which 37 (34.6%) were diagnosed with ICH. Patients with ICH had a significant higher BGL on admission (median 177 mg/dl, IQR: 127-221.75, P < 0.001). In patients with low BGL (<120 mg/dl), higher NWU was associated with 1.34-fold increased likelihood of ICH, while higher NWU was associated with a 2.08-fold increased likelihood of ICH in patients with a high BGL (>200 mg/dl). In multivariable logistic regression analysis, BGL (OR: 1.02, 95% CI: 1.00-1.04, P = 0.01) and NWU (OR: 2.32, 95% CI: 1.44-3.73, P < 0.001) were significantly and independently associated with ICH, showing a significant interaction (P = 0.04). Conclusion: A higher degree of early tissue water uptake and high admission BGL were both independent predictors of ICH. Higher BGL was significantly associated with accelerated effects of NWU on the likelihood of ICH. Although a clear causal relationship remains speculative, stricter BGL control and monitoring may be tested to reduce the risk of ICH in patients undergoing thrombectomy.

Risk Factors for Cerebral Aneurysm Rupture in Mongolia

Purpose

Identification of country-specific demographic, medical, lifestyle, and geoenvironmental risk factors for cerebral aneurysm rupture in the developing Asian country of Mongolia. First-time estimation of the crude national incidence of aneurysmal subarachnoid hemorrhage (aSAH).

Methods

A retrospective analysis of all intracranial digital subtraction angiographies (DSA) acquired in Mongolia during the 2‑year period 2016–2017 (1714 examinations) was performed. During this period, DSA was used as primary diagnostic imaging modality for acute severe neurological symptoms in the sole hospital nationwide dedicated to neurological patients. The catchment area of the hospital included the whole country. Patients with incidental and ruptured aneurysms were reviewed with respect to their medical history and living conditions. The data was used to install a Mongolian aneurysm registry.

Results

The estimated annual crude incidence of cerebral aneurysm rupture was 6.71 for the country of Mongolia and 14.53 per 100,000 persons for the capital region of Ulaanbaatar. Risk factors common in developed countries also applied for the Mongolian population: A medical history of hypertension, smoking or the presence of multiple aneurysms led to a higher relative risk of rupture. In contrast, female gender was not associated with a higher risk in this national cohort. Males pursuing a traditional nomadic living may exhibit a specifically high risk of rupture.

Conclusion

Disease management of over 200 individuals/year with aSAH constitutes a socioeconomic burden in Mongolia. Efforts to raise awareness of the risk factors hypertension and smoking among the Mongolian population are desirable. Measures to improve the nationwide availability of modern neurovascular treatment options are currently under consideration.

Corrigendum: Neoplastic and Non-neoplastic Acute Intracerebral Hemorrhage in CT Brain Scans: Machine Learning-Based Prediction Using Radiomic Image Features

[This corrects the article DOI: 10.3389/fneur.2020.00285.].

Perihematomal Edema and Clinical Outcome in Intracerebral Hemorrhage Related to Different Oral Anticoagulants

BACKGROUND

There is a need to examine the effects of different types of oral anticoagulant-associated intracerebral hemorrhage (OAC-ICH) on perihematomal edema (PHE), which is gaining considerable appeal as a biomarker for secondary brain injury and clinical outcome.

METHODS

In a large multicenter approach, computed tomography-derived imaging markers for PHE (absolute PHE, relative PHE (rPHE), edema expansion distance (EED)) were calculated for patients with OAC-ICH and NON-OAC-ICH. Exploratory analysis for non-vitamin-K-antagonist OAC (NOAC) and vitamin-K-antagonists (VKA) was performed. The predictive performance of logistic regression models, employing predictors of poor functional outcome (modified Rankin scale 4-6), was explored.

RESULTS

Of 811 retrospectively enrolled patients, 212 (26.14%) had an OAC-ICH. Mean rPHE and mean EED were significantly lower in patients with OAC-ICH compared to NON-OAC-ICH, p-value 0.001 and 0.007; whereas, mean absolute PHE did not differ, p-value 0.091. Mean EED was also significantly lower in NOAC compared to NON-OAC-ICH, p-value 0.05. Absolute PHE was an independent predictor of poor clinical outcome in NON-OAC-ICH (OR 1.02; 95%CI 1.002-1.028; p-value 0.027), but not in OAC-ICH (p-value 0.45).

CONCLUSION

Quantitative markers of early PHE (rPHE and EED) were lower in patients with OAC-ICH compared to those with NON-OAC-ICH, with significantly lower levels of EED in NOAC compared to NON-OAC-ICH. Increase of early PHE volume did not increase the likelihood of poor outcome in OAC-ICH, but was independently associated with poor outcome in NON-OAC-ICH. The results underline the importance of etiology-specific treatment strategies. Further prospective studies are needed.

Early Prediction of Malignant Cerebellar Edema in Posterior Circulation Stroke Using Quantitative Lesion Water Uptake

BACKGROUND

Malignant cerebellar edema (MCE) is a life-threatening complication of ischemic posterior circulation stroke that requires timely diagnosis and management. Yet, there is no established imaging biomarker that may serve as predictor of MCE. Early edematous water uptake can be determined using quantitative lesion water uptake, but this biomarker has only been applied in anterior circulation strokes.

OBJECTIVE

To test the hypothesis that lesion water uptake in early posterior circulation stroke predicts MCE.

METHODS

A total 179 patients with posterior circulation stroke and multimodal admission CT were included. A total of 35 (19.5%) patients developed MCE defined by using an established 10-point scale in follow-up CT, of which ≥4 points are considered malignant. Posterior circulation net water uptake (pcNWU) was quantified in admission CT based on CT densitometry and compared with posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) as predictor of MCE using receiver operating curve (ROC) analysis and logistic regression analysis.

RESULTS

Acute pcNWU within the early ischemic lesion was 24.6% (±8.4) for malignant and 7.2% (±7.4) for nonmalignant infarctions, respectively (P < .0001). Based on ROC analysis, pcNWU above 14.9% identified MCE with high discriminative power (area under the curve: 0.94; 95% CI: 0.89-0.97). Early pcNWU (odds ratio [OR]: 1.28; 95% CI: 1.15-1.42, P < .0001) and pc-ASPECTS (OR: 0.71, 95% CI: 0.53-0.95, P = .02) were associated with MCE, adjusted for age and recanalization status.

CONCLUSION

Quantitative pcNWU in early posterior circulation stroke is an important marker for MCE. Besides pc-ASPECTS, lesion water uptake measurements may further support identifying patients at risk for MCE at an early stage indicating stricter monitoring and consideration for further therapeutic measures.

ASPECTS Interobserver Agreement of 100 Investigators from the TENSION Study

Purpose

Evaluating the extent of cerebral ischemic infarction is essential for treatment decisions and assessment of possible complications in patients with acute ischemic stroke. Patients are often triaged according to image-based early signs of infarction, defined by Alberta Stroke Program Early CT Score (ASPECTS). Our aim was to evaluate interrater reliability in a large group of readers.

Methods

We retrospectively analyzed 100 investigators who independently evaluated 20 non-contrast computed tomography (NCCT) scans as part of their qualification program for the TENSION study. Test cases were chosen by four neuroradiologists who had previously scored NCCT scans with ASPECTS between 0 and 8 and high interrater agreement. Percent and interrater agreements were calculated for total ASPECTS, as well as for each ASPECTS region.

Results

Percent agreements for ASPECTS ratings was 28%, with interrater agreement of 0.13 (95% confidence interval, CI 0.09–0.16), at zero tolerance allowance and 66%, with interrater agreement of 0.32 (95% CI: 0.21–0.44), at tolerance allowance set by TENSION inclusion criteria. ASPECTS region with highest level of agreement was the insular cortex (percent agreement = 96%, interrater agreement = 0.96 (95% CI: 0.94–0.97)) and with lowest level of agreement the M3 region (percent agreement = 68%, interrater agreement = 0.39 [95% CI: 0.17–0.61]).

Conclusion

Interrater agreement reliability for total ASPECTS and study enrollment was relatively low but seems sufficient for practical application. Individual region analysis suggests that some are particularly difficult to evaluate, with varying levels of reliability. Potential impairment of the supraganglionic region must be examined carefully, particularly with respect to the decision whether or not to perform mechanical thrombectomy.

Relationship between the degree of recanalization and functional outcome in acute ischemic stroke is mediated by penumbra salvage volume

BACKGROUND

The presence of metabolically viable brain tissue that may be salvageable with rapid cerebral blood flow restoration is the fundament rationale for reperfusion therapy in patients with large vessel occlusion stroke. The effect of endovascular treatment (EVT) on functional outcome largely depends on the degree of recanalization. However, the relationship of recanalization degree and penumbra salvage has not yet been investigated. We hypothesized that penumbra salvage volume mediates the effect of thrombectomy on functional outcome.

METHODS

99 acute anterior circulation stroke patients who received multimodal CT and underwent thrombectomy with resulting partial to complete reperfusion (modified thrombolysis in cerebral infarction scale (mTICI) ≥ 2a) were retrospectively analyzed. Penumbra volume was quantified on CT perfusion and penumbra salvage volume (PSV) was calculated as difference of penumbra and net infarct growth from admission to follow-up imaging.

RESULTS

In patients with complete reperfusion (mTICI ≥ 2c), the median PSV was significantly higher than the median PSV in patients with partial or incomplete (mTICI 2a-2b) reperfusion (median 224 mL, IQR: 168-303 versus 158 mL, IQR: 129-225; p < 0.01). A higher degree of recanalization was associated with increased PSV (+ 63 mL per grade, 95% CI: 17-110; p < 0.01). Higher PSV was also associated with improved functional outcome (OR/mRS shift: 0.89; 95% CI: 0.85-0.95, p < 0.0001).

CONCLUSIONS

PSV may be an important mediator between functional outcome and recanalization degree in EVT patients and could serve as a more accurate instrument to compare treatment effects than infarct volumes.

Imaging-based prediction of histological clot composition from admission CT imaging

BACKGROUND

Thrombus composition has been shown to be a major determinant of recanalization success and occurrence of complications in mechanical thrombectomy. The most important parameters of thrombus behavior during interventional procedures are relative fractions of fibrin and red blood cells (RBCs). We hypothesized that quantitative information from admission non-contrast CT (NCCT) and CT angiography (CTA) can be used for machine learning based prediction of thrombus composition.

METHODS

The analysis included 112 patients with occlusion of the carotid-T or middle cerebral artery who underwent thrombectomy. Thrombi samples were histologically analyzed and fractions of fibrin and RBCs were determined. Thrombi were semi-automatically delineated in CTA scans and NCCT scans were registered to the same space. Two regions of interest (ROIs) were defined for each thrombus: small-diameter ROIs capture vessel walls and thrombi, large-diameter ROIs reflect peri-vascular tissue responses. 4844 quantitative image markers were extracted and evaluated for their ability to predict thrombus composition using random forest algorithms in a nested fivefold cross validation.

RESULTS

Test set receiver operating characteristic area under the curve was 0.83 (95% CI 0.80 to 0.87) for differentiating RBC-rich thrombi and 0.84 (95% CI 0.80 to 0.87) for differentiating fibrin-rich thrombi. At maximum Youden-Index, RBC-rich thrombi were identified at 77% sensitivity and 74% specificity; for fibrin-rich thrombi the classifier reached 81% sensitivity at 73% specificity.

CONCLUSIONS

Machine learning based analysis of admission imaging allows for prediction of clot composition. Perspectively, such an approach could allow selection of clot-specific devices and retrieval procedures for personalized thrombectomy strategies.

Effect of thrombectomy on oedema progression and clinical outcome in patients with a poor collateral profile

Background and purpose

The impact of the cerebral collateral circulation on lesion progression and clinical outcome in ischaemic stroke is well established. Moreover, collateral status modifies the effect of endovascular treatment and was therefore used to select patients for therapy in prior trials. The purpose of this study was to quantify the effect of vessel recanalisation on lesion pathophysiology and clinical outcome in patients with a poor collateral profile.

Materials and methods

129 patients who had an ischaemic stroke with large vessel occlusion in the anterior circulation and a collateral score (CS) of 0–2 were included. Collateral profile was defined using an established 5-point scoring system in CT angiography. Lesion progression was determined using quantitative lesion water uptake measurements on admission and follow-up CT (FCT), and clinical outcome was assessed using modified Rankin Scale (mRS) scores after 90 days.

Results

Oedema formation in FCT was significantly lower in patients with vessel recanalisation compared with patients with persistent vessel occlusion (mean 19.5%, 95% CI: 17% to 22% vs mean 27%, 95% CI: 25% to 29%; p<0.0001). In a multivariable linear regression analysis, vessel recanalisation was significantly associated with oedema formation in FCT (ß=−7.31, SD=0.015, p<0.0001), adjusted for CS, age and Alberta Stroke Program Early CT Score (ASPECTS). Functional outcome was significantly better in patients following successful recanalisation (mRS at day 90: 4.5, IQR: 2–6 vs 5, IQR: 5–6, p<0.001).

Conclusion

Although poor collaterals are known to be associated with poor outcome, endovascular recanalisation was still associated with significant oedema reduction and comparably better outcome in this patient group. Patients with poor collaterals should not generally be excluded from thrombectomy.

Computed tomography-based triage of extensive baseline infarction: ASPECTS and collaterals versus perfusion imaging for outcome prediction

BACKGROUND

Patients presenting with large baseline infarctions are often excluded from mechanical thrombectomy (MT) due to uncertainty surrounding its effect on outcome. We hypothesized that computed tomography perfusion (CTP)-based selection may be predictive of functional outcome in low Alberta Stroke Program Early CT Score (ASPECTS) patients.

METHODS

This was a double-center, retrospective analysis of patients presenting with ASPECTS≤5 who received multimodal admission CT imaging between May 2015 and June 2020. The predicted ischemic core (pCore) was defined as a reduction in cerebral blood flow (rCBF), while mismatch volume was defined using time to maximum (Tmax). The pCore perfusion mismatch ratio (CPMR) was also calculated. These parameters (pCore, mismatch volume, and CPMR), as well as a combined radiological score consisting of ASPECTS and collateral status (ASCO score), were tested in logistic regression and receiver operating characteristic (ROC) analyses. The primary outcome was favorable modified Rankin Scale (mRS) at discharge (≤3).

RESULTS

A total of 113 patients met the inclusion criteria. The median ischemic core volume was 74.1 mL (IQR 43.8-121.8). The ASCO score was associated with favorable outcome at discharge (aOR 3.7, 95% CI 1.8 to 10.7, P=0.002), while no association was observed for the CTP parameters. A model including the ASCO score also had significantly higher area under the curve (AUC) values compared with the CTP-based model (0.88 vs 0.64, P=0.018).

CONCLUSIONS

The ASCO score was superior to the CTP-based model for the prediction of good functional outcome and could represent a quick, practical, and easily implemented method for the selection of low ASPECTS patients most likely benefit from MT.

Early clinical surrogates for outcome prediction after stroke thrombectomy in daily clinical practice

BACKGROUND AND PURPOSE

To investigate early clinical surrogates for long-term independency of patients treated with thrombectomy for large vessel occlusion stroke in daily clinical routine.

METHODS

All patients with anterior circulation stroke enrolled in the German Stroke Registry-Endovascular Treatment from 07/2015 to 04/2018 were analysed. National Institute of Health Stroke Scale (NIHSS) on admission, NIHSS percentage change, NIHSS delta and NIHSS at 24 hours as well as existing binary definitions of early neurological improvement (ENI; improvement of 8 (major ENI)/10 (dramatic ENI) NIHSS points or reaching 0/1 were compared for predicting functional outcome at 90 days using the modified Rankin Scale (mRS). Excellent and favourable outcome were defined as 0-1 and 0-2, respectively.

RESULTS

Among 2262 endovasculary treated patients with acute ischaemic anterior circulation stroke, NIHSS at 24 hours had the highest discriminative ability to predict excellent (receiver operator characteristics (ROC)_{NIHSS 24 hours} area under the curve (AUC) 0.86 (0.84-0.88)) and favourable long-term functional outcome (ROC_{NIHSS 24 hours} AUC 0.86 (0.85-0.88)) in comparison to NIHSS percentage change (ROC_{% change} AUC mRS ≤1: 0.81 (0.78-0.83) mRS ≤2: 0.81 (0.79-0.83)), NIHSS delta change (ROC_{Δ change} AUC mRS ≤1: 0.74 (0.72-0.77), mRS ≤2: 0.77 (0.74-0.79)) and NIHSS admission (ROC_Adm AUC mRS ≤1: 0.70 (0.68-0.73), mRS ≤2: 0.67 (0.68-0.71)). Advanced age was the only independent predictor (adjusted OR 1.05, 95% CI 1.03 to 1.07, p<0.001) for turning the outcome prognosis from favourable (mRS ≤2) to poor (mRS ≥4) at 90 days.

CONCLUSION

The NIHSS at 24 hours postintervention with a threshold of ≤8 points serves best as a surrogate for long-term functional outcome after thrombectomy for anterior circulation stroke in daily clinical practice. Only advanced age significantly decreases its predictive value.

Clinical and Imaging Characteristics in Patients with SARS-CoV-2 Infection and Acute Intracranial Hemorrhage

BACKGROUND AND PURPOSE

Intracranial hemorrhage has been observed in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19), but the clinical, imaging, and pathophysiological features of intracranial bleeding during COVID-19 infection remain poorly characterized. This study describes clinical and imaging characteristics of patients with COVID-19 infection who presented with intracranial bleeding in a European multicenter cohort.

METHODS

This is a multicenter retrospective, observational case series including 18 consecutive patients with COVID-19 infection and intracranial hemorrhage. Data were collected from February to May 2020 at five designated European special care centers for COVID-19. The diagnosis of COVID-19 was based on laboratory-confirmed diagnosis of SARS-CoV-2. Intracranial bleeding was diagnosed on computed tomography (CT) of the brain within one month of the date of COVID-19 diagnosis. The clinical, laboratory, radiologic, and pathologic findings, therapy and outcomes in COVID-19 patients presenting with intracranial bleeding were analyzed.

RESULTS

Eighteen patients had evidence of acute intracranial bleeding within 11 days (IQR 9-29) of admission. Six patients had parenchymal hemorrhage (33.3%), 11 had subarachnoid hemorrhage (SAH) (61.1%), and one patient had subdural hemorrhage (5.6%). Three patients presented with intraventricular hemorrhage (IVH) (16.7%).

CONCLUSION

This study represents the largest case series of patients with intracranial hemorrhage diagnosed with COVID-19 based on key European countries with geospatial hotspots of SARS-CoV-2. Isolated SAH along the convexity may be a predominant bleeding manifestation and may occur in a late temporal course of severe COVID-19.

Clinical relevance of asymptomatic intracerebral hemorrhage post thrombectomy depends on angiographic collateral score

Asymptomatic intracerebral hemorrhage (aICH) is a common phenomenon in patients with acute ischemic stroke (AIS) treated with endovascular thrombectomy (ET). However, the impact of aICH on the functional outcome remains widely unclear. In this study, we aimed at identifying predictors for aICH and analyzing its impact on functional outcome. Patients with AIS due to large artery occlusion in the anterior circulation treated with successful ET were enrolled in a tertiary stroke center. Patients with aICH or without intracerebral hemorrhage were included according to post-treatment CT performed within 72 h; 100 consecutive patients fulfilled the inclusion criteria and 30% classified with aICH. In logistic regression analysis, lower collateral score (OR 0.24; 95% CI 0.12-0.46, p < 0.0001) was significantly associated with aICH. Less patients with aICH achieved an independent outcome (mRS 0-2, 16.7% vs. 44.3%, p = 0.007). Poor outcome (mRS 4-6) was significantly higher in patients with aICH (41.4% vs. 70%, p = 0.021). Patients with aICH had a lower ratio of independent outcome (OR 0.23, 95% CI 0.05-0.1.05, p = 0.041) than without ICH. There were no differences concerning poor outcome (p = 0.5). Lower collateral status was a strong independent predictor for aICH. aICH after successful ET may decrease the likelihood of an independent functional outcome without influencing poor outcome.

Small thrombus size, thrombus composition, and poor collaterals predict pre-interventional thrombus migration

BACKGROUND

Different imaging characteristics such as clot burden score, collaterals, and pre-interventional thrombus migration are associated with functional outcome in patients with acute ischemic stroke. Moreover, histological thrombus composition is associated with pre-interventional thrombus migration. We hypothesized that smaller clots may more likely migrate and that collateral status in ischemic stroke patients may mediate this tendency of the clot to migrate.

METHODS

In this prospective cohort of consecutive ischemic stroke patients, clot burden scores and collateral scores were rated and the retrieved thrombi were histologically analyzed. We then investigated the relationship between clot burden score, probability for thrombus migration, and collateral scores using mediation analysis.

RESULTS

163 patients are included of which 36 (22.1%) had a clot migration. Probability of thrombus migration was significantly associated with lower collateral scores (P<0.01), higher clot burden scores (P<0.01), shorter thrombi (P<0.01), and higher RBC count (P<0.01). In the mediator pathway, higher collateral scores were significantly associated with higher clot burden scores (P<0.01) and younger age (P=0.029). The total effect of an increase in clot burden score by one grade on thrombus migration is composed of the direct effect (+18%, P<0.01) and the collateral score-mediated indirect effect (-5%, P<0.01).

CONCLUSIONS

Smaller, erythrocyte-rich thrombi tend to migrate more often. Good collaterals seem to have a considerable effect on limiting migration. This supports the hypothesis that larger clots have stronger adherence with the vessel wall and that good collaterals increase the counter pressure distal of the clot.

Incomplete or failed thrombectomy in acute stroke patients with Alberta Stroke Program Early Computed Tomography Score 0-5 - how harmful is trying?

BACKGROUND AND PURPOSE

It is currently unknown whether mechanical thrombectomy (MT) for ischaemic stroke patients with low initial Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is clinically beneficial or even harmful. The purpose of this study was to investigate whether failed or incomplete MT in acute large vessel occlusion stroke with an initial ASPECTS ≤ 5 is associated with worse clinical outcome compared to patients not undergoing MT.

METHODS

This observational cohort study included a consecutive sample of patients with anterior circulation stroke and initial ASPECTS ≤ 5 admitted between March 2015 and August 2019. Failed recanalization was defined as Thrombolysis in Cerebral Infarction (TICI) score 0-2a, and incomplete recanalization as TICI 2b. Clinical outcome was assessed using the modified Rankin Scale (mRS) at 90 days defining very poor clinical outcome as mRS > 4.

RESULTS

One hundred and seventy patients were included. Ninety-nine patients underwent MT and 71 patients received best medical treatment only. Clinical outcome after failed or incomplete MT (TICI 0-2b) was significantly better compared to patients with medical treatment only (median mRS 5, interquartile range 4-6 vs 5-6, P = 0.03). In multivariable logistic regression analysis, failed or incomplete MT (TICI 0-2b) showed a significantly reduced likelihood for very poor outcome (odds ratio 0.39, 95% confidence interval 0.19-0.83, P = 0.01). Failed MT (TICI 0-2a) was not associated with a worse outcome compared to best medical treatment.

CONCLUSIONS

Patients with failed or incomplete recanalization results (TICI 0-2b) showed a reduced likelihood for very poor outcome compared with those who did not receive MT. Evidence from randomized trials is needed to confirm that even failed or incomplete MT is not harmful in these patients.

Feasibility and safety of thrombectomy for isolated occlusions of the posterior cerebral artery: a multicenter experience and systematic literature review

BACKGROUND

Substantial clinical evidence supporting the benefit of mechanical thrombectomy (MT) for distal occlusions within the posterior circulation is still missing. This study aims to investigate the procedural feasibility and safety of MT for isolated occlusions of the posterior cerebral artery.

METHODS

We retrospectively reviewed patients from three stroke centers with acute ischemic stroke attributed to isolated posterior cerebral artery occlusion (IPCAOs) who underwent MT between January 2014 and December 2019. Procedural and safety assessment included successful recanalization rates (defined as Thrombolysis in Cerebral Infarction Scale (TICI) ≥2b), number of MT attempts and first-pass effect (TICI 3), intracranial hemorrhage (ICH), mortality, and intervention-related serious adverse events. Treatment effects were evaluated by the rate of early neurological improvement (ENI) and early functional outcome was assessed with the modified Rankin Scale (mRS) at discharge. A systematic literature review was conducted to identify and summarize previous reports on MT for IPCAOs.

RESULTS

Forty-three patients with IPCAOs located in the P1 (55.8%, 24/43), P2 (37.2%, 16/43), and P3 segment (7%, 3/43) were analyzed. The overall rate of successful recanalization (TICI ≥2b) was 86% (37/43), including a first pass-effect of 48.8% (21/43) leading to TICI 3. sICH occurred in 7% (3/43) and there were two cases with iatrogenic vessel dissection and one perforation. ENI was observed in 59% (23/39) and excellent functional outcome (mRS ≤1) in 46.2% (18/39) of patients who were discharged. The in-hospital mortality rate was 9.3% (4/43).

CONCLUSION

Our study suggests the technical feasibility and safety of thrombectomy for IPCAOs. Further studies are needed to investigate safety and long-term functional outcomes with posterior circulation stroke-adjusted outcome assessment.