Post-Thrombolysis Recanalization in Stroke Referrals for Thrombectomy

Outcomes of Bridging Intravenous Thrombolysis Versus Endovascular Therapy Alone in Late-Window Acute Ischemic Stroke

BACKGROUND

Studies comparing bridging intravenous thrombolysis (IVT) with direct endovascular therapy (EVT) in patients with acute ischemic stroke who present late are limited. We aimed to compare the clinical outcomes and safety of bridging IVT in patients with acute ischemic stroke due to anterior circulation large vessel occlusion who underwent EVT 6 to 24 hours after time last known well.

METHODS

We enrolled patients with anterior circulation large vessel occlusion stroke and a National Institutes of Health Stroke Scale score of ≥6 from 20 centers across 10 countries in the multicenter retrospective CLEAR study (CT for Late Endovascular Reperfusion) between January 2014 and May 2022. We used inverse probability of treatment weighting modeling adjusted for clinical and imaging confounders to compare functional outcomes, reperfusion success, symptomatic intracranial hemorrhage, and mortality between EVT patients with and without prior IVT.

RESULTS

Of 5098 patients screened for eligibility, we included 2749 patients, of whom 549 received bridging IVT before EVT. The timing of IVT was not recorded. Witnessed stroke onset and transfer rates were higher in the bridging IVT group (25% versus 12% and 77% versus 55%, respectively, P value for both <0.0001), and time intervals between stroke onset and treatment were shorter (time last known well-start of EVT median 560 minutes [interquartile range, 432-791] versus 724 minutes [interquartile range, 544-912]; P<0.0001). After adjustment for confounders, there was no difference in functional outcome at 3 months (adjusted common odds ratio for modified Rankin Scale shift, 1.03 [95% CI, 0.89-1.19]; P=0.72) or successful reperfusion (adjusted odds ratio, 1.19 [95% CI, 0.81-1.75]; P=0.39). There were no safety concerns associated with bridging IVT versus direct EVT (symptomatic intracranial hemorrhage: adjusted odds ratio, 0.75 [95% CI, 0.38-1.48]; P=0.40; mortality: adjusted odds ratio, 1.14 [95% CI, 0.89-1.46]; P=0.31). Results were unchanged when the analysis was limited to patients who received IVT >6 hours after last known well.

CONCLUSIONS

In patients with an anterior circulation large vessel occlusion stroke who underwent EVT 6 to 24 hours from last known well, bridging IVT was not associated with a difference in outcomes compared with direct EVT.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04096248.

Arterial Recanalization During Interhospital Transfer for Thrombectomy

BACKGROUND

Patients with acute ischemic stroke harboring a large vessel occlusion admitted to nonendovascular-capable centers often require interhospital transfer for thrombectomy. We evaluated the incidence and predictors of arterial recanalization during transfer, as well as the relationship between interhospital recanalization and clinical outcomes.

METHODS

We analyzed data from 2 cohorts of patients with an anterior circulation large vessel occlusion transferred for consideration of thrombectomy to a comprehensive center, with arterial imaging at the referring hospital and on comprehensive stroke center arrival. Interhospital recanalization was determined by comparison of the baseline and posttransfer arterial imaging and was defined as revised arterial occlusive lesion (rAOL) score 2b to 3. Pretransfer variables independently associated with interhospital recanalization were studied using multivariable logistic regression analysis.

RESULTS

Of the 520 included patients (Montpellier, France, n=237; Stanford, United States, n=283), 111 (21%) experienced interhospital recanalization (partial [rAOL=2b] in 77% and complete [rAOL=3] in 23%). Pretransfer variables independently associated with recanalization were intravenous thrombolysis (adjusted odds ratio, 6.8 [95% CI, 4.0-11.6]), more distal occlusions (intracranial carotid occlusion as reference: adjusted odds ratio, 2.0 [95% CI, 0.9-4.5] for proximal first segment of the middle cerebral artery, 5.1 [95% CI, 2.3-11.5] for distal first segment of the middle cerebral artery, and 5.0 [95% CI, 2.1-11.8] for second segment of the middle cerebral artery), and smaller clot burden (clot burden score 0-4 as reference: adjusted odds ratio, 3.4 [95% CI, 1.5-7.6] for 5-7 and 5.6 [95% CI, 2.4-12.7] for 8-9). Recanalization on arrival at the comprehensive center was associated with less interhospital infarct growth (rAOL, 0-2a: 11.6 mL; rAOL, 2b: 2.2 mL; rAOL, 3: 0.6 mL; Ptrend<0.001) and greater interhospital National Institutes of Health Stroke Scale score improvement (0 versus -5 versus -6; Ptrend<0.001). Interhospital recanalization was associated with reduced 3-month disability (adjusted common odds ratio, 2.51 [95% CI, 1.68-3.77]) with greater benefit from complete than partial recanalization.

CONCLUSIONS

Recanalization is frequently observed during interhospital transfer for thrombectomy and is strongly associated with favorable outcomes, even when partial. Broadening thrombolysis indications in primary centers, and developing therapies that increase recanalization during transfer, will likely improve clinical outcomes.

Clinical change during inter-hospital transfer for thrombectomy: Incidence, associated factors, and relationship with outcome

BACKGROUND

Patients with acute ischemic stroke with a large vessel occlusion (LVO) admitted to non endovascular-capable centers often require inter-hospital transfer for thrombectomy. We aimed to describe the incidence of substantial clinical change during transfer, the factors associated with clinical change, and its relationship with 3-month outcome.

METHODS

We analyzed data from two cohorts of acute stroke patients transferred for thrombectomy to a comprehensive center (Stanford, USA, November 2019 to January 2023; Montpellier, France, January 2015 to January 2017), regardless of whether thrombectomy was eventually attempted. Patients were included if they had evidence of an LVO at the referring hospital and had a National Institute of Health Stroke Scale (NIHSS) score documented before and immediately after transfer. Inter-hospital clinical change was categorized as improvement (⩾4 points and ⩾25% decrease between the NIHSS score in the referring hospital and upon comprehensive center arrival), deterioration (⩾4 points and ⩾25% increase), or stability (neither improvement nor deterioration). The stable group was considered as the reference and was compared to the improvement or deterioration groups separately.

RESULTS

A total of 504 patients were included, of whom 22% experienced inter-hospital improvement, 14% deterioration, and 64% were stable. Pre-transfer variables independently associated with clinical improvement were intravenous thrombolysis use, more distal occlusions, and lower serum glucose; variables associated with deterioration included more proximal occlusions and higher serum glucose. On post-transfer imaging, clinical improvement was associated with arterial recanalization and smaller infarct growth and deterioration with larger infarct growth. As compared to stable patients, those with clinical improvement had better 3-month functional outcome (adjusted common odds ratio (cOR) = 2.43; 95% confidence interval (CI) = 1.59-3.71; p < 0.001), while those with deterioration had worse outcome (adjusted cOR = 0.60; 95% CI = 0.37-0.98; p = 0.044).

CONCLUSION

Substantial inter-hospital clinical changes are frequently observed in LVO-related ischemic strokes, with significant impact on functional outcome. There is a need to develop treatments that improves the clinical status during transfer.

DATA ACCESS STATEMENT

The data that support the findings of this study are available upon reasonable request.

Thrombus Imaging Characteristics to Predict Early Recanalization in Anterior Circulation Large Vessel Occlusion Stroke

The early management of transferred patients with a large vessel occlusion (LVO) stroke could be improved by identifying patients who are likely to recanalize early. We aim to predict early recanalization based on patient clinical and thrombus imaging characteristics. We included 81 transferred anterior-circulation LVO patients with an early recanalization, defined as the resolution of the LVO or the migration to a distal location not reachable with endovascular treatment upon repeated radiological imaging. We compared their clinical and imaging characteristics with all (322) transferred patients with a persistent LVO in the MR CLEAN Registry. We measured distance from carotid terminus to thrombus (DT), thrombus length, density, and perviousness on baseline CT images. We built logistic regression models to predict early recanalization. We validated the predictive ability by computing the median area-under-the-curve (AUC) of the receiver operating characteristics curve for 100 5-fold cross-validations. The administration of intravenous thrombolysis (IVT), longer transfer times, more distal occlusions, and shorter, pervious, less dense thrombi were characteristic of early recanalization. After backward elimination, IVT administration, DT and thrombus density remained in the multivariable model, with an AUC of 0.77 (IQR 0.72-0.83). Baseline thrombus imaging characteristics are valuable in predicting early recanalization and can potentially be used to optimize repeated imaging workflow.

Early Recanalization Among Patients Undergoing Bridging Therapy With Tenecteplase or Alteplase

BACKGROUND

Intravenous thrombolysis (IVT) with alteplase or tenecteplase before mechanical thrombectomy is the recommended treatment for large-vessel occlusion acute ischemic stroke. There are divergent data on whether these agents differ in terms of early recanalization (ER) rates before mechanical thrombectomy, and little data on their potential differences stratified by ER predictors such as IVT to ER evaluation (IVT-to-EReval) time, occlusion site and thrombus length.

METHODS

We retrospectively compared the likelihood of ER after IVT with tenecteplase or alteplase in anterior circulation large-vessel occlusion acute ischemic stroke patients from the PREDICT-RECANAL (alteplase) and Tenecteplase Treatment in Ischemic Stroke (tenecteplase) French multicenter registries. ER was defined as a modified Thrombolysis in Cerebral Infarction score 2b-3 on the first angiographic run, or noninvasive vascular imaging in patients with early neurological improvement. Analyses were based on propensity score overlap weighting (leading to exact balance in patient history, stroke characteristics, and initial management between groups) and confirmed with adjusted logistic regression (sensitivity analysis). A stratified analysis based on pre-established ER predictors (IVT-to-EReval time, occlusion site, and thrombus length) was conducted.

RESULTS

Overall, 1865 patients were included. ER occurred in 156/787 (19.8%) and 199/1078 (18.5%) patients treated with tenecteplase or alteplase, respectively (odds ratio, 1.09 [95% CI, 0.83-1.44]; P=0.52). A differential effect of tenecteplase versus alteplase on the probability of ER according to thrombus length was observed (Pinteraction=0.003), with tenecteplase being associated with higher odds of ER in thrombi >10 mm (odds ratio, 2.43 [95% CI, 1.02-5.81]; P=0.04). There was no differential effect of tenecteplase versus alteplase on the likelihood of ER according to the IVT-to-EReval time (Pinteraction=0.40) or occlusion site (Pinteraction=0.80).

CONCLUSIONS

Both thrombolytics achieved ER in one-fifth of patients with large-vessel occlusion acute ischemic stroke without significant interaction with IVT-to-EReval time and occlusion site. Compared with alteplase, tenecteplase was associated with a 2-fold higher likelihood of ER in larger thrombi.

Endovascular Thrombectomy Outcomes with and without Intravenous Thrombolysis for Large Ischemic Cores Identified with CT or MRI

Background Whether intravenous thrombolysis (IVT) prior to endovascular thrombectomy (EVT) provides additional benefits in patients with acute ischemic stroke (AIS) and a large infarct core (LIC) remains unclear. Purpose To examine whether treatment with IVT before EVT is beneficial in patients with LIC identified with CT or MRI (Alberta Stroke Program Early CT score 0-5). Materials and Methods This retrospective study included consecutive adult patients diagnosed with AIS due to large vessel occlusion (LVO) and LIC treated with EVT who were enrolled in the ETIS (Endovascular Treatment in Ischemic Stroke) Registry in France between January 2015 and January 2022. The primary outcome measure was a favorable outcome (modified Rankin Scale [mRS] score 0-3) at 90 days. Secondary outcomes included functional independence (mRS score 0-2) at 90 days, improvement in degree of disability (ordinal shift in mRS score toward a better outcome) at 90 days, early neurologic improvement at 24 hours, and successful reperfusion (modified Thrombolysis in Cerebral Infarction score of 2b or higher). Safety outcomes included symptomatic intracerebral hemorrhage within 24 hours and mortality at 90 days. Inverse probability of treatment weighting (IPTW)-adjusted analysis was used to assess the treatment effect of IVT adjusted for baseline variables. Results Of 1408 patients (mean age, 68.3 years ± 15.4 [SD]; 789 men), 654 (46.4%) were treated with IVT prior to EVT. In the IPTW-adjusted data set, IVT plus EVT was associated with a higher rate of favorable outcome at 90 days (odds ratio [OR], 1.24 [95% CI: 1.05, 1.46]; P = .01), functional independence at 90 days (OR, 1.47 [95% CI: 1.22, 1.77]; P < .001), improvement in degree of disability at 90 days (common OR, 1.30 [95% CI: 1.13, 1.49]; P < .001), early neurologic improvement (OR, 1.26 [95% CI: 1.07, 1.49]; P = .005), and successful reperfusion (OR, 1.43 [95% CI: 1.14, 1.79]; P = .002) than EVT alone. Rates of brain hemorrhage within 24 hours and mortality at 90 days were similar between groups. Conclusion In patients with AIS due to LVO with LIC identified with CT or MRI, treatment with IVT before EVT appeared to provide a clinical benefit over EVT alone. Clinical trial registration no. NCT03776877 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Kallmes and Rabinstein in this issue.

Tenecteplase Improves Reperfusion across Time in Large Vessel Stroke

OBJECTIVE

Tenecteplase improves reperfusion compared to alteplase in patients with large vessel occlusions. To determine whether this improvement varies across the spectrum of thrombolytic agent to reperfusion assessment times, we performed a comparative analysis of tenecteplase and alteplase reperfusion rates.

METHODS

Patients with large vessel occlusion and treatment with thrombolysis were pooled from the Melbourne Stroke Registry, and the EXTEND-IA and EXTEND-IA TNK trials. The primary outcome, thrombolytic-induced reperfusion, was defined as the absence of retrievable thrombus or >50% reperfusion at imaging reassessment. We compared the treatment effect of tenecteplase and alteplase, accounting for thrombolytic to assessment exposure times, via Poisson modeling. We compared 90-day outcomes of patients who achieved reperfusion with a thrombolytic to patients who achieved reperfusion via endovascular therapy using ordinal logistic regression.

RESULTS

Among 893 patients included in the primary analysis, thrombolytic-induced reperfusion was observed in 184 (21%) patients. Tenecteplase was associated with higher rates of reperfusion (adjusted incidence rate ratio [aIRR] = 1.50, 95% confidence interval [CI] = 1.09-2.07, p = 0.01). Findings were consistent in patient subgroups with first segment (aIRR = 1.41, 95% CI = 0.93-2.14) and second segment (aIRR = 2.07, 95% CI = 0.98-4.37) middle cerebral artery occlusions. Increased thrombolytic to reperfusion assessment times were associated with reperfusion (tenecteplase: adjusted risk ratio [aRR] = 1.08 per 15 minutes, 95% CI = 1.04-1.13 vs alteplase: aRR = 1.06 per 15 minutes, 95% CI = 1.00-1.13). No significant treatment-by-time interaction was observed (p = 0.87). Reperfusion via thrombolysis was associated with improved 90-day modified Rankin Scale scores (adjusted common odds ratio = 2.15, 95% CI = 1.54-3.01) compared to patients who achieved reperfusion following endovascular therapy.

INTERPRETATION

Tenecteplase, compared to alteplase, increases prethrombectomy reperfusion, regardless of the time from administration to reperfusion assessment. Prethrombectomy reperfusion is associated with better clinical outcomes. ANN NEUROL 2023;93:489-499.

FLAIR Vascular Hyperintensities as a Surrogate of Collaterals in Acute Stroke: DWI Matters

BACKGROUND AND PURPOSE

FLAIR vascular hyperintensities are thought to represent leptomeningeal collaterals in acute ischemic stroke. However, whether all-FLAIR vascular hyperintensities or FLAIR vascular hyperintensities-DWI mismatch, ie, FLAIR vascular hyperintensities beyond the DWI lesion, best reflects collaterals remains debated. We aimed to compare the value of FLAIR vascular hyperintensities-DWI mismatch versus all-FLAIR vascular hyperintensities for collateral assessment using PWI-derived collateral flow maps as a reference.

MATERIALS AND METHODS

We retrospectively reviewed the registries of 6 large stroke centers and included all patients with acute stroke with anterior circulation large-vessel occlusion who underwent MR imaging with PWI before thrombectomy. Collateral status was graded from 1 to 4 on PWI-derived collateral flow maps and dichotomized into good (grades 3-4) and poor (grades 1-2). The extent of all-FLAIR vascular hyperintensities and FLAIR vascular hyperintensities-DWI mismatch was assessed on the 7 cortical ASPECTS regions, ranging from 0 (absence) to 7 (extensive), and associations with good collaterals were compared using receiver operating characteristic curves.

RESULTS

Of the 209 included patients, 133 (64%) and 76 (36%) had good and poor collaterals, respectively. All-FLAIR vascular hyperintensity extent was similar between collateral groups (P = .76). Conversely, FLAIR vascular hyperintensities-DWI mismatch extent was significantly higher in patients with good compared with poor collaterals (P < .001). The area under the curve was 0.80 (95% CI, 0.74-0.87) for FLAIR vascular hyperintensities-DWI mismatch and 0.52 (95% CI, 0.44-0.60) for all-FLAIR vascular hyperintensities (P < .001 for the comparison), to predict good collaterals. Variables independently associated with good collaterals were smaller DWI lesion volume (P < .001) and larger FLAIR vascular hyperintensities-DWI mismatch (P = .02).

CONCLUSIONS

In acute ischemic stroke with large-vessel occlusion, the extent of FLAIR vascular hyperintensities does not reliably reflect collateral status unless one accounts for DWI.

Efficacy of Mechanical Thrombectomy Using an Aspiration Catheter Compared with a Stent Retriever Alone for Middle Cerebral Artery M2 Occlusion

Objective

Mechanical thrombectomy (MT) for middle cerebral artery M2 occlusion (M2O) is challenging because the procedure is performed in a narrow and tortuous artery. In this study, we compared MT using an aspiration catheter (AC) versus a stent retriever (SR) used alone, and retrospectively evaluated the efficacy and safety of MT using an AC for M2O.

Methods

Seventy-four consecutive patients who underwent MT for M2O at our institution between April 2016 and April 2020 were evaluated. The subjects were classified into those treated by AC (AC group) or SR alone (SR group). The AC group included patients treated by both contact aspiration and a combination technique of AC and SR. Background factors and outcomes, including modified treatment in cerebral infarction (mTICI) 2c-3 recanalization, were compared between the groups.

Results

AC and SR groups consisted of 47 and 27 patients respectively. Among them, the rate of mTICI 2b-3 was 93.6% vs 92.6%, and that of mTICI 2c-3 was 72.3% vs 48.2% (P = 0.004). The perioperative symptomatic subarachnoid hemorrhage (SAH) rate was 0% vs 7.4%, and modified Rankin scale scores of 0-2 were 78.6% vs 50% (P = 0.03). In the AC group, the mTICI 2c-3 rate was higher in patients in whom the AC was adequately advanced to the thrombus compared to those with inadequate AC advancement (83.3% vs 36.3%, P = 0.002).

Conclusion

The rate of mTICI 2c-3 was higher in the AC than SR group, with no cases of symptomatic SAH. MT using AC for M2O might achieve safe and effective thrombectomy.

The End of Tissue-Type Plasminogen Activator's Reign?

Mechanical thrombectomy is a highly effective treatment for acute ischemic stroke caused by large-vessel occlusion in the anterior cerebral circulation, significantly increasing the likelihood of recovery to functional independence. Until recently, whether intravenous thrombolysis before mechanical thrombectomy provided additional benefits to patients with acute ischemic stroke-large-vessel occlusion remained unclear. Given that reperfusion is a key factor for clinical outcome in patients with acute ischemic stroke-large-vessel occlusion and the efficacy of both intravenous thrombolysis and mechanical thrombectomy is time-dependent, achieving complete reperfusion with a single pass should be the primary angiographic goal. However, it remains undetermined whether extending the procedure with additional endovascular attempts or local lytics administration safely leads to higher reperfusion grades and whether there are significant public health and cost implications. Here, we outline the current state of knowledge and research avenues that remain to be explored regarding the consistent therapeutic benefit of intravenous thrombolysis in anterior circulation strokes and the potential place of adjunctive intra-arterial lytics administration, including alternative thrombolytic agent place.

European Stroke Organisation (ESO)-European Society for Minimally Invasive Neurological Therapy (ESMINT) expedited recommendation on indication for intravenous thrombolysis before mechanical thrombectomy in patients with acute ischemic stroke and anterior circulation large vessel occlusion

Six randomized controlled clinical trials have assessed whether mechanical thrombectomy (MT) alone is non-inferior to intravenous thrombolysis (IVT) plus MT within 4.5 hours of symptom onset in patients with anterior circulation large vessel occlusion (LVO) ischemic stroke and no contraindication to IVT. An expedited recommendation process was initiated by the European Stroke Organisation (ESO) and conducted with the European Society of Minimally Invasive Neurological Therapy (ESMINT) according to ESO standard operating procedure based on the GRADE system. We identified two relevant Population, Intervention, Comparator, Outcome (PICO) questions, performed systematic reviews and meta-analyses of the literature, assessed the quality of the available evidence, and wrote evidence-based recommendations. Expert opinion was provided if insufficient evidence was available to provide recommendations based on the GRADE approach.For stroke patients with anterior circulation LVO directly admitted to a MT-capable center ('mothership') within 4.5 hours of symptom onset and eligible for both treatments, we recommend IVT plus MT over MT alone (moderate evidence, strong recommendation). MT should not prevent the initiation of IVT, nor should IVT delay MT. In stroke patients with anterior circulation LVO admitted to a center without MT facilities and eligible for IVT ≤4.5 hours and MT, we recommend IVT followed by rapid transfer to a MT capable-center ('drip-and-ship') in preference to omitting IVT (low evidence, strong recommendation). Expert consensus statements on ischemic stroke on awakening from sleep are also provided. Patients with anterior circulation LVO stroke should receive IVT in addition to MT if they have no contraindications to either treatment.

EXPRESS: European Stroke Organisation (ESO) – European Society for Minimally Invasive Neurological Therapy (ESMINT) expedited recommendation on indication for intravenous thrombolysis before mechanical thrombectomy in patients with acute ischaemic stroke and anterior circulation large vessel occlusion

Six randomized controlled clinical trials have assessed whether mechanical thrombectomy (MT) alone is non-inferior to intravenous thrombolysis (IVT) plus MT within 4.5 hours of symptom onset in patients with anterior circulation large vessel occlusion (LVO) ischaemic stroke and no contraindication to IVT. An expedited recommendation process was initiated by the European Stroke Organisation (ESO) and conducted with the European Society of Minimally Invasive Neurological Therapy (ESMINT) according to ESO standard operating procedure based on the GRADE system. We identified two relevant Population, Intervention, Comparator, Outcome (PICO) questions, performed systematic reviews and meta-analyses of the literature, assessed the quality of the available evidence, and wrote evidence-based recommendations. Expert opinion was provided if insufficient evidence was available to provide recommendations based on the GRADE approach. For stroke patients with anterior circulation LVO directly admitted to a MT-capable centre (“mothership”) within 4.5 hours of symptom onset and eligible for both treatments, we recommend IVT plus MT over MT alone (moderate evidence, strong recommendation). MT should not prevent the initiation of IVT, nor should IVT delay MT. In stroke patients with anterior circulation LVO admitted to a centre without MT facilities and eligible for IVT ≤4.5 hrs and MT, we recommend IVT followed by rapid transfer to a MT capable-centre (“drip-and-ship”) in preference to omitting IVT (low evidence, strong recommendation). Expert consensus statements on ischaemic stroke on awakening from sleep are also provided. Patients with anterior circulation LVO stroke should receive IVT in addition to MT if they have no contraindications to either treatment.

Effect of Occlusion Site on the Safety and Efficacy of Intravenous Alteplase Before Endovascular Thrombectomy: A Prespecified Subgroup Analysis of DIRECT-MT

BACKGROUND AND PURPOSE

Recent trials showed thrombectomy alone was comparable to bridging therapy in patients with anterior circulation large vessel occlusion eligible for both intravenous alteplase and endovascular thrombectomy. We performed this study to examine whether occlusion site modifies the effect of intravenous alteplase before thrombectomy.

METHODS

This is a prespecified subgroup analysis of a randomized trial evaluating risk and benefit of intravenous alteplase before thrombectomy (DIRECT-MT [Direct Intra-Arterial Thrombectomy in Order to Revascularize AIS Patients With Large Vessel Occlusion Efficiently in Chinese Tertiary Hospitals]). Among 658 randomized patients, 640 with baseline occlusion site information were included. The primary outcome was the score on the modified Rankin Scale at 90 days. Multivariable ordinal logistic regression analysis with an interaction term was used to estimate treatment effect modification by occlusion location (internal carotid artery versus M1 versus M2). We report the adjusted common odds ratio for a shift toward better outcome on the modified Rankin Scale after thrombectomy alone compared with combination treatment adjusted for age, the National Institutes of Health Stroke Scale score at baseline, the time from stroke onset to randomization, the modified Rankin Scale score before stroke onset, and collateral score per the DIRECT-MT statistical analysis plan.

RESULTS

The overall adjusted common odds ratio was 1.08 (95% CI, 0.82-1.43) with thrombectomy alone compared with combination treatment, and there was no significant treatment-by-occlusion site interaction (P=0.47). In subgroups based on occlusion location, we found the following adjusted common odds ratios: 0.99 (95% CI, 0.62-1.59) for internal carotid artery occlusions, 1.12 (95% CI, 0.77-1.64) for M1 occlusions, and 1.22 (95% CI, 0.53-2.79) for M2 occlusions. No treatment-by-occlusion site interactions were observed for dichotomized modified Rankin Scale distributions and successful reperfusion (extended thrombolysis in Cerebral Infarction score ≥2b) before thrombectomy. Differences in symptomatic hemorrhage rate were not significant between occlusion locations (internal carotid artery occlusion: 7.02% in bridging therapy versus 7.14% for thrombectomy alone, P=0.97; M1 occlusion: 5.06% versus 2.48%, P=0.22; M2 occlusion: 9.09% versus 4.76%; P=0.78).

CONCLUSIONS

In this prespecified subgroup of a randomized trial, we found no evidence that occlusion location can inform intravenous alteplase decisions in endovascular treatment eligible patients directly presenting at endovascular treatment capable centers. Future studies are needed to confirm our findings. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03469206.

Functional Outcome, Recanalization, and Hemorrhage Rates After Large Vessel Occlusion Stroke Treated With Tenecteplase Before Thrombectomy

BACKGROUND AND OBJECTIVES

To investigate in routine care the efficacy and safety of IV thrombolysis (IVT) with tenecteplase prior to mechanical thrombectomy (MT) in patients with large vessel occlusion acute ischemic strokes (LVO-AIS), either secondarily transferred after IVT or directly admitted to a comprehensive stroke center (CSC).

METHODS

We retrospectively analyzed clinical and procedural data of patients treated with 0.25 mg/kg tenecteplase within 270 minutes of LVO-AIS who underwent brain angiography. The main outcome was 3-month functional independence (modified Rankin Scale score ≤2). Recanalization (revised Treatment in Cerebral Ischemia score 2b-3) was evaluated before (pre-MT) and after MT (final).

RESULTS

We included 588 patients (median age 75 years [interquartile range (IQR) 61-84]; 315 women [54%]; median NIH Stroke Scale score 16 [IQR 10-20]), of whom 520 (88%) were secondarily transferred after IVT. Functional independence occurred in 47% (n = 269/570; 95% confidence interval [CI] 43.0-51.4) of patients. Pre-MT recanalization occurred in 120 patients (20.4%; 95% CI 17.2-23.9), at a similar rate across treatment paradigms (direct admission, n = 14/68 [20.6%]; secondary transfer, n = 106/520 [20.4%]; p > 0.99) despite a shorter median IVT to puncture time in directly admitted patients (38 [IQR 23-55] vs 86 [IQR 70-110] minutes; p < 0.001). Final recanalization was achieved in 492 patients (83.7%; 95%CI 80.4-86.6). Symptomatic intracerebral hemorrhage occurred in 2.5% of patients (n = 14/567; 95% CI 1.4-4.1).

DISCUSSIONS

Tenecteplase before MT is safe, effective, and achieves a fast recanalization in everyday practice in patients secondarily transferred or directly admitted to a CSC, in line with published results. These findings should encourage its wider use in bridging therapy.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that tenecteplase within 270 minutes of LVO-AIS increases the probability of functional independence.

Impact of Strategy on Clinical Outcome in Large Vessel Occlusion Stroke Successfully Reperfused: ETIS Registry Results

BACKGROUND AND PURPOSE

Approximately half of the patients with acute ischemic stroke due to anterior circulation large vessel occlusion do not achieve functional independence despite successful reperfusion. We aimed to determine influence of reperfusion strategy (bridging therapy, intravenous thrombolysis alone, or mechanical thrombectomy alone) on clinical outcomes in this population.

METHODS

From ongoing, prospective, multicenter, observational Endovascular Treatment in Ischemic Stroke registry in France, all patients with anterior circulation large vessel occlusion who achieved successful reperfusion (modified Thrombolysis in Cerebral Infarction 2b-3) following reperfusion therapy were included. Primary end point was favorable outcome, defined as 90-day modified Rankin Scale score ≤2. Patient groups were compared using those treated with bridging therapy as reference. Differences in baseline characteristics were reduced after propensity score-matching, with a maximum absolute standardized difference of 14% for occlusion site.

RESULTS

Among 1872 patients included, 970 (51.8%) received bridging therapy, 128 (6.8%) received intravenous thrombolysis alone, and the remaining 774 (41.4%) received MT alone. The rate of favorable outcome was comparable between groups. Excellent outcome (90-day modified Rankin Scale score 0-1) was achieved more frequently in the bridging therapy group compared with the MT alone (odds ratio after propensity score-matching, 0.70 [95% CI, 0.50-0.96]). Regarding safety outcomes, hemorrhagic complications were similar between the groups, but 90-day mortality was significantly higher in the MT alone group compared with the bridging therapy group (odds ratio, 1.60 [95% CI, 1.09-2.37]).

CONCLUSIONS

This real-world observational study of patients with anterior circulation large vessel occlusion demonstrated a similar rate of favorable outcome following successful reperfusion with different therapeutic strategies. However, our results suggest that bridging therapy compared with MT alone is significantly associated with excellent clinical outcome and lower mortality.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03776877.

Standard- vs. low-dose rivaroxaban in patients with atrial fibrillation: a systematic review and meta-analysis

PURPOSE

Low-dose rivaroxaban is often given to patients with atrial fibrillation (AF) around the world, but the rationale for its use remains unclear. We aimed to compare the efficacy and safety of standard- or low-dose rivaroxaban in patients with AF through systematic review of literature with meta-analysis.

METHODS

We searched PubMed, Web of Science, EMBASE, Clinical Trials.gov, the Cochrane Library, and Bayer trial website from inception of each database until June 2020. Randomized controlled trials (RCTs) and cohort studies were included in the meta-analysis. A random-effects model was employed to calculate the pooled effect estimates.

RESULTS

Two RCTs and 17 cohort studies were included in the qualitative analysis. Indirect comparison of RCTs showed no significant difference between the two rivaroxaban dosages in risk of efficacy or safety outcomes (p > 0.05). Indirect comparison of cohort studies showed a lower risk of MACE among Caucasians in standard-dose group (HR 0.779; 95% CI 0.687-0.884; p < 0.001). Bleeding outcomes did not differ significantly between the two dosage regimens in Asian or Caucasian populations, except that the standard dose was associated with higher risk of major bleeding among elderly Caucasian patients (HR 1.329; 95% CI 1.141-1.547; p < 0.001). The quality of evidence was rated ranging from very low to low for all the efficacy and safety outcomes.

CONCLUSION

In Caucasians with AF, standard-dose rivaroxaban may prevent MACE significantly better than low-dose treatment. Further studies in Asians are needed to verify the advantages of the standard dose.

Optimizing Emergency Stroke Transport Strategies Using Physiological Models

Supplemental Digital Content is available in the text.

The criteria for choosing between drip and ship and mothership transport strategies in emergency stroke care is widely debated. Although existing data-driven probability models can inform transport decision-making at an epidemiological level, we propose a novel mathematical, physiologically derived framework that provides insight into how patient characteristics underlying infarct core growth influence these decisions.

Thrombolytic strategies for ischemic stroke in the thrombectomy era

Twenty-five years ago, intravenous thrombolysis has revolutionized the care of patients with acute ischemic stroke. Since 2015, randomized clinical trials have demonstrated that mechanical thrombectomy improves functional outcome in stroke patients over intravenous thrombolysis alone. More recently, three randomized clinical trials have suggested that mechanical thrombectomy alone is noninferior to a combined strategy with both intravenous thrombolysis and mechanical thrombectomy. In the present review, we will present the last clinical and preclinical studies on the use of thrombolysis in stroke patients in the modern thrombectomy era. At the cost of a potential increased risk of hemorrhagic transformation, thrombolysis may promote arterial recanalization before thrombectomy, improve the rate of successful recanalization after thrombectomy, and restore microcirculation patency downstream of the main thrombus. Besides, new thrombolytic strategies targeting tissue-type plasminogen activator resistant thrombi are being developed, which could strengthen the beneficial effects of thrombolysis without carrying additional pro-hemorrhagic effects. For instance, tenecteplase has shown improved rate of recanalization compared with tissue-type plasminogen activator (alteplase). Beyond fibrinolysis, DNA- and von Willebrand factor-targeted thrombolytic strategies have shown promising results in experimental models of ischemic stroke. New combined strategies, improved thrombolytics, and dedicated clinical trials in selected patients are eagerly awaited to further improve functional outcome in stroke.

Early recanalization in large-vessel occlusion stroke patients transferred for endovascular treatment

Background

We performed an exploratory analysis to identify patient and thrombus characteristics associated with early recanalization in large-vessel occlusion (LVO) stroke patients transferred for endovascular treatment (EVT) from a primary (PSC) to a comprehensive stroke center (CSC).

Methods

We included patients with an LVO stroke of the anterior circulation who were transferred to our hospital for EVT and underwent repeated imaging between January 2016 and June 2019. We compared patient characteristics, workflow time metrics, functional outcome (modified Rankin Scale at 90 days), and baseline thrombus imaging characteristics, which included: occlusion location, thrombus length, attenuation, perviousness, distance from terminus of intracranial carotid artery to the thrombus (DT), and clot burden score (CBS), between early-recanalized LVO (ER-LVO), and non-early-recanalized LVO (NER-LVO) patients.

Results

One hundred and forty-nine patients were included in the analysis. Early recanalization occurred in 32% of patients. ER-LVO patients less often had a medical history of hypertension (31% vs 49%, P=0.04), and more often had clinical improvement between PSC and CSC (ΔNIHSS −5 vs 3, P<0.01), compared with NER-LVO patients. Thrombolysis administration was similar in both groups (88% vs 78%, P=0.18). ER-LVO patients had no ICA occlusions (0% vs 27%, P<0.01), more often an M2 occlusion (35% vs 17%, P=0.01), longer DT (27 mm vs 12 mm, P<0.01), shorter thrombi (17 mm vs 27 mm, P<0.01), and higher CBS (8 vs 6, P<0.01) at baseline imaging. ER-LVO patients had lower mRS scores (1 vs 3, P=0.02).

Conclusions

Early recanalization is associated with clinical improvement between PSC and CSC admission, more distal occlusions and shorter thrombi at baseline imaging, and better functional outcome.

Cost Effectiveness of Interhospital Transfer for Mechanical Thrombectomy of Acute Large Vessel Occlusion Stroke: Role of Predicted Recanalization Rates

BACKGROUND

Emergency interhospital transfer of patients with stroke with large vessel occlusion to a comprehensive stroke center for mechanical thrombectomy is resource-intensive and can be logistically challenging. Imaging markers may identify patients in whom intravenous thrombolysis (IVT) alone is likely to result in thrombus resolution, potentially rendering interhospital transfers unnecessary. Here, we investigate how predicted probabilities to achieve IVT-mediated recanalization affect cost-effectiveness estimates of interhospital transfer.

METHODS

We performed a health economic analysis comparing emergency interhospital transfer of patients with acute large vessel occlusion stroke after administration of IVT with a scenario in which patients also receive IVT but remain at the primary hospital. Results were stratified by clinical parameters, treatment delays, and the predicted probability to achieve IVT-mediated recanalization. Estimated 3-month outcomes were combined with a long-term probabilistic model to yield quality-adjusted life years (QALYs) and costs. Uncertainty was quantified in probabilistic sensitivity analyses.

RESULTS

Depending on input parameters, marginal costs of interhospital transfer ranged from USD -61 366 (cost saving) to USD +20 443 and additional QALYs gained from 0.1 to 3.0, yielding incremental cost-effectiveness ratios of <USD 0 (dominant) to USD 310 000 per QALY. For some elderly patients with moderate or severe stroke symptoms treated in a remote primary stroke center, transfer was unlikely to be cost effective at a willingness-to-pay threshold of USD 100 000 and 50 000 per QALY (20% and 1%, respectively) if the predicted probability to achieve IVT-related recanalization was high. On the other hand, in some younger patients, the analysis yielded incremental cost-effectiveness ratio estimates below USD 20 000 per QALY independent of the predicted recanalization rate.

CONCLUSIONS

Predicted probabilities to achieve IVT-mediated recanalization significantly affect the cost-effectiveness of interhospital transfer for MT, in particular in elderly patients with moderate or severe stroke symptoms. However, high predicted recanalization rates alone do not generally imply that patients should not be considered for transfer.

Prediction of Early Neurological Deterioration in Individuals With Minor Stroke and Large Vessel Occlusion Intended for Intravenous Thrombolysis Alone

Importance

The best reperfusion strategy in patients with acute minor stroke and large vessel occlusion (LVO) is unknown. Accurately predicting early neurological deterioration of presumed ischemic origin (ENDi) following intravenous thrombolysis (IVT) in this population may help to select candidates for immediate transfer for additional thrombectomy.

Objective

To develop and validate an easily applicable predictive score of ENDi following IVT in patients with minor stroke and LVO.

Design, Setting, and Participants

This multicentric retrospective cohort included 729 consecutive patients with minor stroke (National Institutes of Health Stroke Scale [NIHSS] score of 5 or less) and LVO (basilar artery, internal carotid artery, first [M1] or second [M2] segment of middle cerebral artery) intended for IVT alone in 45 French stroke centers, ie, including those who eventually received rescue thrombectomy because of ENDi. For external validation, another cohort of 347 patients with similar inclusion criteria was collected from 9 additional centers. Data were collected from January 2018 to September 2019.

Main Outcomes and Measures

ENDi, defined as 4 or more points' deterioration on NIHSS score within the first 24 hours without parenchymal hemorrhage on follow-up imaging or another identified cause.

Results

Of the 729 patients in the derivation cohort, 335 (46.0%) were male, and the mean (SD) age was 70 (15) years; of the 347 patients in the validation cohort, 190 (54.8%) were male, and the mean (SD) age was 69 (15) years. In the derivation cohort, the median (interquartile range) NIHSS score was 3 (1-4), and the occlusion site was the internal carotid artery in 97 patients (13.3%), M1 in 207 (28.4%), M2 in 395 (54.2%), and basilar artery in 30 (4.1%). ENDi occurred in 88 patients (12.1%; 95% CI, 9.7-14.4) and was strongly associated with poorer 3-month outcomes, even in patients who underwent rescue thrombectomy. In multivariable analysis, a more proximal occlusion site and a longer thrombus were independently associated with ENDi. A 4-point score derived from these variables-1 point for thrombus length and 3 points for occlusion site-showed good discriminative power for ENDi (C statistic = 0.76; 95% CI, 0.70-0.82) and was successfully validated in the validation cohort (ENDi rate, 11.0% [38 of 347]; C statistic = 0.78; 95% CI, 0.70-0.86). In both cohorts, ENDi probability was approximately 3%, 7%, 20%, and 35% for scores of 0, 1, 2 and 3 to 4, respectively.

Conclusions and Relevance

The substantial ENDi rates observed in these cohorts highlights the current debate regarding whether to directly transfer patients with IVT-treated minor stroke and LVO for additional thrombectomy. Based on the strong associations observed, an easily applicable score for ENDi risk prediction that may assist decision-making was derived and externally validated.

CTA Protocols in a Telestroke Network Improve Efficiency for Both Spoke and Hub Hospitals

BACKGROUND AND PURPOSE

Telestroke networks support screening for patients with emergent large-vessel occlusions who are eligible for endovascular thrombectomy. Ideal triage processes within telestroke networks remain uncertain. We characterize the impact of implementing a routine spoke hospital CTA protocol in our integrated telestroke network on transfer and thrombectomy patterns.

MATERIALS AND METHODS

A protocol-driven CTA process was introduced at 22 spoke hospitals in November 2017. We retrospectively identified prospectively collected patients who presented to a spoke hospital with National Institutes of Health Stroke Scale scores ≥6 between March 1, 2016 and March 1, 2017 (pre-CTA), and March 1, 2018 and March 1, 2019 (post-CTA). We describe the demographics, CTA utilization, spoke hospital retention rates, emergent large-vessel occlusion identification, and rates of endovascular thrombectomy.

RESULTS

There were 167 patients pre-CTA and 207 post-CTA. The rate of CTA at spoke hospitals increased from 15% to 70% (P < .001). Despite increased endovascular thrombectomy screening in the extended window, the overall rates of transfer out of spoke hospitals remained similar (56% versus 54%; P = .83). There was a nonsignificant increase in transfers to our hub hospital for endovascular thrombectomy (26% versus 35%; P = .12), but patients transferred >4.5 hours from last known well increased nearly 5-fold (7% versus 34%; P < .001). The rate of endovascular thrombectomy performed on patients transferred for possible endovascular thrombectomy more than doubled (22% versus 47%; P = .011).

CONCLUSIONS

Implementation of CTA at spoke hospitals in our telestroke network was feasible and improved the efficiency of stroke triage. Rates of patients retained at spoke hospitals remained stable despite higher numbers of patients screened. Emergent large-vessel occlusion confirmation at the spoke hospital lead to a more than 2-fold increase in thrombectomy rates among transferred patients at the hub.

Role of neuroimaging before reperfusion therapy. Part 1 - IV thrombolysis - Review

This review paper summarises the yield of the different imaging modalities in the evaluation of patients for IV thrombolysis. Non-contrast CT and CTA or brain MRI combined with MRA are the recommended sequences for the evaluation of patients within the 4.5 hours time window. Multimodal MRI (DWI/PWI), and more recently, CT perfusion, offer reliable surrogate of salvageable penumbra, the target mismatch, which is now currently used as selection criteria for revascularisation treatment in an extended time window. Those sequences may also help the physician for the management of other limited cases when the diagnosis of acute ischemic stroke is difficult. Another approach the DWI/FLAIR mismatch has been proposed to identify among wake-up stroke patients those who have been experiencing an acute ischemic stroke evolving from less than 4.5hrs. Other biomarkers, such as the clot imaging on MRI and CT, help to predict the recanalisation rate after IVT, while the impact of the presence microbleeds on MRI remains to be determined.

Time from I.V. Thrombolysis to Thrombectomy and Outcome in Acute Ischemic Stroke

OBJECTIVE

Whether the time from intravenous thrombolysis (IVT) to endovascular treatment (EVT) in patients with acute ischemic stroke has an effect on the functional outcome is unknown.

METHODS

The Endovascular Treatment in Ischemic Stroke (ETIS) registry is an ongoing, prospective, multicenter, observational study that perform EVT in France. Data were analyzed from patients treated by IVT and EVT between October 2013 and December 2018 in 6 comprehensive stroke centers. In the primary analysis, we assessed the association of time from IVT administration to start of EVT with functional outcome (measured with the modified Rankin Scale [mRS]), by means of ordinal logistic regression. Secondary end points included angiographic and safety outcomes.

RESULTS

We analyzed 1,986 patients with acute ischemic stroke due to anterior circulation large vessel occlusion who underwent IVT and EVT. An increased IVT to start of EVT time was associated with a worse functional outcome at 90 days (mRS = 0-2, adjusted odds ratio [OR] per 30 minutes increase in time = 0.91, 95% confidence interval [CI] = 0.86-0.96; mRS = 0-1, adjusted OR per 30 minutes increase in time = 0.89, 95% CI = 0.84-0.94), a lower chance of modified Thrombolysis in Cerebral Infarction (mTICI) grade 2b to 3 reperfusion (adjusted OR per 30 minutes increase in time = 0.93, 95% CI = 0.87-0.98), and an increased probability of symptomatic intracerebral hemorrhage (adjusted OR per 30 minutes increase in time = 1.09, 95% CI = 0.99-1.18).

INTERPRETATION

These findings provide a basis for further studies to determine if the functional outcome of patients with stroke can be greatly improved by optimizing IVT to EVT times. ANN NEUROL 2021;89:511-519.

Thrombus Migration and Fragmentation After Intravenous Alteplase Treatment: The INTERRSeCT Study

BACKGROUND AND PURPOSE

There is interest in what happens over time to the thrombus after intravenous alteplase. We study the effect of alteplase on thrombus structure and its impact on clinical outcome in patients with acute stroke.

METHODS

Intravenous alteplase treated stroke patients with intracranial internal carotid artery or middle cerebral artery occlusion identified on baseline computed tomography angiography and with follow-up vascular imaging (computed tomography angiography or first run of angiography before endovascular therapy) were enrolled from INTERRSeCT study (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography). Thrombus movement after intravenous alteplase was classified into complete recanalization, thrombus migration, thrombus fragmentation, and no change. Thrombus migration was diagnosed when occlusion site moved distally and graded according to degrees of thrombus movement (grade 0-3). Thrombus fragmentation was diagnosed when a new distal occlusion in addition to the primary occlusion was identified on follow-up imaging. The association between thrombus movement and clinical outcome was also evaluated.

RESULTS

Among 427 patients in this study, thrombus movement was seen in 54% with a median time of 123 minutes from alteplase administration to follow-up imaging, and sub-classified as marked (thrombus migration grade 2-3 + complete recanalization; 27%) and mild to moderate thrombus movement (thrombus fragmentation + thrombus migration grade 0-1; 27%). In patients with proximal M1/internal carotid artery occlusion, marked thrombus movement was associated with a higher rate of good outcome (90-day modified Rankin Scale, 0-2) compared with mild to moderate movement (52% versus 27%; adjusted odds ratio, 5.64 [95% CI, 1.72-20.10]). No difference was seen in outcomes between mild to moderate thrombus movement and no change. In M1 distal/M2 occlusion, marked thrombus movement was associated with improved 90-day good outcome compared with no change (70% versus 56%; adjusted odds ratio, 2.54 [95% CI, 1.21-5.51]).

CONCLUSIONS

Early thrombus movement is common after intravenous alteplase. Marked thrombus migration leads to good clinical outcomes. Thrombus dynamics over time should be further evaluated in clinical trials of acute reperfusion therapy.

Two Cases of Posterior Cerebral Artery P2 Segment Occlusion with Motor Weakness Improved by Acute Mechanical Thrombectomy

BACKGROUND

Clinical evidence to support the use of mechanical thrombectomy (MT) for posterior cerebral artery P2 segment occlusion (P2O) has not been established, and hemiplegia due to P2O improved by MT to our knowledge has not yet been reported. We report 2 cases of P2O with hemiplegia improved by MT.

CASE DESCRIPTION

In case 1, a 68-year-old man was admitted with right hemiplegia and dysesthesia (National Institutes of Health Stroke Scale score 14). Head magnetic resonance imaging showed acute ischemia in the left inferolateral thalamus and posterior limb of the internal capsule. Angiography showed left P2O, which was recanalized after MT. Hemiplegia improved immediately following recanalization, and modified Rankin Scale score at discharge was 0. In case 2, a 69-year-old man was admitted with left hemiplegia and dysesthesia (National Institutes of Health Stroke Scale score 8). Head magnetic resonance imaging showed acute ischemia in the right inferolateral thalamus and posterior limb of the internal capsule. Angiography showed right P2O, which was recanalized after MT, as in case 1. His symptoms resolved completely.

CONCLUSIONS

P2O may cause severe motor deficit. In such cases, MT may contribute to safely improving patients' deficits.

Bridging Therapy or IV Thrombolysis in Minor Stroke with Large Vessel Occlusion

OBJECTIVE

Whether bridging therapy (intravenous thrombolysis [IVT] followed by endovascular treatment) is superior to IVT alone in minor stroke with large vessel occlusion (LVO) is unknown.

METHODS

Multicentric retrospective observational study including, in intention-to-treat, consecutive IVT-treated minor strokes (National Institutes of Health Stroke Scale [NIHSS] ≤ 5) with LVO, with or without additional mechanical thrombectomy. Propensity-score (inverse probability of treatment weighting) was used to reduce baseline between-groups differences. The primary outcome was excellent outcome, that is, modified Rankin score 0 to 1 at 3 months follow-up.

RESULTS

Overall, 598 patients were included (214 and 384 in the bridging therapy and IVT groups, respectively). Following propensity-score weighting, the distribution of baseline clinical and radiological variables was similar across the two patient groups. Compared with IVT alone, bridging therapy was not associated with excellent outcome (odds ratio [OR] = 0.96; 95% confidence interval [CI] = 0.75-1.24; p = 0.76), but was associated with symptomatic intracranial hemorrhage (OR = 3.01; 95% CI = 1.77-5.11; p < 0.0001). Occlusion site was a strong modifier of the effect of bridging therapy on outcome (p_interaction < 0.0001), with bridging therapy associated with higher odds of excellent outcome in proximal M1 (OR = 3.26; 95% CI = 1.67-6.35; p = 0.0006) and distal M1 (OR = 1.69; 95% CI = 1.01-2.82; p = 0.04) occlusions, but with lower odds of excellent outcome for M2 (OR = 0.53; 95% CI = 0.38-0.75; p = 0.0003) occlusions. Bridging therapy was associated with higher rates of symptomatic intracranial hemorrhage in M2 occlusions only (OR = 4.40; 95% CI = 2.20-8.83; p < 0.0001).

INTERPRETATION

Although overall outcomes were similar in intended bridging therapy as compared to intended IVT alone in minor strokes with LVO, our results suggest that intended bridging therapy may be beneficial in M1 occlusions, whereas the benefit-risk profile may favor IVT alone in M2 occlusions. ANN NEUROL 2020 ANN NEUROL 2020;88:160-169.

Relationships between brain perfusion and early recanalization after intravenous thrombolysis for acute stroke with large vessel occlusion

In large vessel occlusion (LVO) stroke, it is unclear whether severity of ischemia is involved in early post-thrombolysis recanalization over and above thrombus site and length. Here we assessed the relationships between perfusion parameters and early recanalization following intravenous thrombolysis administration in LVO patients. From a multicenter registry, we identified 218 thrombolysed LVO patients referred for thrombectomy with both (i) pre-thrombolysis MRI, including diffusion-weighted imaging (DWI), T2*-imaging, MR-angiography and dynamic susceptibility-contrast perfusion-weighted imaging (PWI); and (ii) evaluation of recanalization on first angiographic run or non-invasive imaging ≤ 3 h from thrombolysis start. Infarct core volume on DWI, PWI-DWI mismatch volume and hypoperfusion intensity ratio (HIR; defined as Tmax ≥ 10 s volume/ Tmax ≥ 6 s volume, low HIR indicating milder hypoperfusion) were determined using a commercially available software. Early recanalization occurred in 34 (16%) patients, and multivariable analysis was associated with lower HIR (P = 0.006), shorter thrombus on T2*-imaging (P < 0.001) and more distal occlusion (P = 0.006). However, the relationship between HIR and early recanalization was robust only for thrombus length <14 mm. In summary, the present study disclosed an association between lower HIR and early post-thrombolysis recanalization. Early post-thrombolysis recanalization is therefore determined not only by thrombus site and length but also by severity of ischemia.

Bypassing the Closest Stroke Center for Thrombectomy Candidates

Background and Purpose—

Patients with acute ischemic stroke who have large vessel occlusion benefit from direct transport to a comprehensive stroke center (CSC) capable of endovascular therapy. To avoid harm for patients without large vessel occlusion from delayed access to intravenous thrombolysis (IVT), it has been suggested to only redirect patients with high likelihood of large vessel occlusion for whom the additional delay to intravenous thrombolysis (IVT) caused by transport to the CSC is below a certain threshold. However, which threshold achieves the greatest clinical benefit is unknown.

Methods—

We used mathematical modeling to calculate additional-delay-to-IVT thresholds associated with the greatest reduction in disability-adjusted life years in abstracted 2-stroke center and multiple-stroke center scenarios. Model parameters were extracted from recent meta-analyses or large prospective cohort studies. Uncertainty was quantified in probabilistic and 2-way univariate sensitivity analyses.

Results—

Assuming ideal treatment time performance metrics, transport to the nearest CSC was the preferred strategy irrespective of additional delay-to-IVT when the transfer time between primary stroke center and CSC was <40 minutes (95% credible interval: 25–66 minutes); otherwise, the optimal additional delay-to-IVT-threshold ranged from 28 to 139 minutes. In multiple-stroke center scenarios, optimal additional-delay-to-IVT thresholds were 30 to 54 minutes in urban and 49 to 141 minutes in rural settings; use of optimal thresholds as compared with a 15 minute-threshold saved 0 to 0.11 and 0 to 0.37 disability-adjusted life years per triage case, respectively. Assuming slower treatment times at primary stroke centers and CSCs yielded longer permissible additional delays.

Conclusions—

Our results suggest that patients with acute ischemic stroke with suspected large vessel occlusion should be redirected to a CSC if the additional delay to IVT is <30 minutes in urban and 50 minutes in rural settings.

Current Smoking Does Not Modify the Treatment Effect of Intravenous Thrombolysis in Acute Ischemic Stroke Patients-A Post-hoc Analysis of the WAKE-UP Trial

Background: The “smoking paradox” indicates that patients with acute ischemic stroke (AIS) who smoke at the time of their stroke may have a better prognosis after intravenous thrombolysis than non-smokers. However, findings are inconsistent and data analyzing the effect of smoking on treatment efficacy of intravenous thrombolysis are scarce.

Methods: We performed a pre-specified post-hoc subgroup analysis of the Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke (WAKE-UP) trial that randomized AIS patients with unknown time of symptom onset who had diffusion-weighted imaging-fluid attenuation inversion recovery (DWI-FLAIR) mismatch to either alteplase or placebo. Patients were categorized as current smokers or non-smokers (including former smokers and never-smokers). Baseline demographic and clinical characteristics, as well as clinical and imaging follow-up data were analyzed according to smoking status.

Results: Four hundred and eighty six patients were included in the analysis. Current smokers (133, 27.4%) were younger (60.1 ± 13.0 vs. 67.2 ± 10.3 years; p < 0.001) and less often had arterial hypertension (45.0% vs. 56.8%; p = 0.02) or atrial fibrillation (3.8% vs. 15.3%; p < 0.001). The acute stroke presentation was more often due to large vessel occlusion among current smokers (27.1 vs. 16.2%; p = 0.01), and smokers had a trend towards more severe strokes (National Institutes of Health Stroke Scale score>10 in 27.1% vs. 19.5%; p = 0.08). The treatment effect of alteplase, quantified as odds ratio for a favorable outcome (modified Rankin Scale [mRS] score at 90 days of 0 or 1), did not differ between current smokers and non-smokers (p-value for interaction: 0.59). After adjustment for age and stroke severity, neither the proportion of patients with favorable outcome, nor the median mRS score at 90 days differed between current smokers and non-smokers. When additional potential confounders were included in the model, the median mRS score was higher in current smokers than in non-smokers (cOR of better outcome for current smokers vs. non-smokers: 0.664 [0.451–0.978], p = 0.04).

Conclusions: In patients with mild to moderate MRI-proven AIS and unknown time of symptom onset with DWI-FLAIR mismatch, current smokers had worse functional outcome as compared to non-smokers. Current smoking did not modify the treatment effect of alteplase.

Clinical Trial registration: Main trial (WAKE-UP): ClinicalTrials.gov, NCT01525290; and EudraCT, 2011-005906-32. Registered 02 February 2012.

Severe Stroke Patients With Left-Sided Occlusion of the Proximal Anterior Circulation Benefit More From Thrombectomy

Background and Purpose: Endovascular thrombectomy improves the functional independence of patients with proximal anterior circulation occlusion. However, a subset of patients fail to benefit from thrombectomy procedures, the reasons for which remain poorly defined. In this study, we investigated whether the effectiveness of thrombectomy was affected by left- or right-sided occlusion among patients with similar stroke severities.

Methods: Patients with proximal anterior circulation occlusion (internal carotid or M1 of middle cerebral artery) treated with the Solitaire stent retriever within 8 h of the onset of acute ischemic stroke were enrolled from the Yijishan Hospital of Wannan Medical College. Stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS) on admission. The functional outcomes were assessed using the modified Rankin scale (mRS) at 90 days.

Results: We enrolled 174 patients including 90 left-sided occlusion and 84 right-sided occlusion. The NIHSS scores on admission were higher in the left-sided (median, 19; interquartile range, 16 to 20) compared to the right-sided occlusion group (median, 15, interquartile range, 13 to 18) (P < 0.001). Following adjustment for potential risk factors, patients with left-sided occlusion had higher rates of functional independence (mRS ≤ 2) and lower rates of mortality (mRS = 6) compared to the right-sided occlusion patients (39.5 vs. 19.6% and 28.9 vs. 47.8%, respectively) in the severe stroke group (NIHSS ≥ 15).

Conclusions: In severe stroke patients with proximal anterior circulation occlusion, stent retriever thrombectomy within 8 h of the onset of symptoms provides more benefits to left-sided occlusion.

Better Collaterals Are Independently Associated With Post-Thrombolysis Recanalization Before Thrombectomy

Background and Purpose—

In acute stroke patients with large vessel occlusion, the goal of intravenous thrombolysis (IVT) is to achieve early recanalization (ER). Apart from occlusion site and thrombus length, predictors of early post-IVT recanalization are poorly known. Better collaterals might also facilitate ER, for instance, by improving delivery of the thrombolytic agent to both ends of the thrombus. In this proof-of-concept study, we tested the hypothesis that good collaterals independently predict post-IVT recanalization before thrombectomy.

Methods—

Patients from the registries of 6 French stroke centers with the following criteria were included: (1) acute stroke with large vessel occlusion treated with IVT and referred for thrombectomy between May 2015 and March 2017; (2) pre-IVT brain magnetic resonance imaging, including diffusion-weighted imaging, T2*, MR angiography, and dynamic susceptibility contrast perfusion-weighted imaging; and (3) ER evaluated ≤3 hours from IVT start on either first angiographic run or noninvasive imaging. A collateral flow map derived from perfusion-weighted imaging source data was automatically generated, replicating a previously validated method. Thrombus length was measured on T2*-based susceptibility vessel sign.

Results—

Of 224 eligible patients, 37 (16%) experienced ER. ER occurred in 10 of 83 (12%), 17 of 116 (15%), and 10 of 25 (40%) patients with poor/moderate, good, and excellent collaterals, respectively. In multivariable analysis, better collaterals were independently associated with ER ( P =0.029), together with shorter thrombus ( P <0.001) and more distal occlusion site ( P =0.010).

Conclusions—

In our sample of patients with stroke imaged with perfusion-weighted imaging before IVT and intended for thrombectomy, better collaterals were independently associated with post-IVT recanalization, supporting our hypothesis. These findings strengthen the idea that advanced imaging may play a key role for personalized medicine in identifying patients with large vessel occlusion most likely to benefit from IVT in the thrombectomy era.

Clinical effect of successful reperfusion in patients presenting with NIHSS < 8: data from the BEYOND-SWIFT registry

BACKGROUND AND PURPOSE

If patients presenting with large vessel occlusions (LVO) and mild symptoms should be treated with endvoascular treatment (EVT) remains unclear. Aims of this study were (1) assessing the safety and technical efficacy of EVT in patients with NIHSS < 8 as opposed to a comparison group of patients presenting with NIHSS ≥ 8 and (2) evaluation of the clinical effect of reperfusion in patients with NIHSS < 8.

METHODS

Patients included into the retrospective multicenter BEYOND-SWIFT registry (NCT03496064) were analyzed. Clinical effect of achieving successful reperfusion (defined as modified Thrombolysis in Cerebral Infarction grade 2b/3) in patients presenting with NIHSS < 8 (N = 193) was evaluated using multivariable logistic regression analyses (displayed as adjusted Odds Ratios, aOR and 95% confidence intervals, 95%-CI). Primary outcome was excellent functional outcome (modified Rankin Scale, mRS 0-1) at day 90. Safety and efficacy of mechanical thrombectomy in patients with NIHSS < 8 was compared to patients presenting with NIHSS ≥ 8 (N = 1423).

RESULTS

Among patients with NIHSS < 8 (N = 193, 77/193, 39.9% receiving pre-interventional IV-tPA), successful reperfusion was significantly related to mRS 0-1 (aOR 3.217, 95%-CI 1.174-8.816) and reduced the chances of non-hemorrhagic neurological worsening (aOR 0.194, 95%-CI 0.050-0.756) after adjusting for prespecified confounders. In interaction analyses, the relative merits of achieving successful reperfusion were mostly comparable between patients presenting with NIHSS < 8 and NIHSS ≥ 8 as evidenced by non-significantly different aOR. Interventional safety and efficacy metrics were similar between patients with NIHSS < 8 and NIHSS ≥ 8.

CONCLUSIONS

Achieving successful reperfusion is beneficial in patients with persisting LVO presenting with NIHSS < 8 and reduces the risk of non-hemorrhagic neurological worsening.