Advances in mechanical thrombectomy for acute ischaemic stroke from large vessel occlusions

Systems-level computational modeling in ischemic stroke: from cells to patients

Ischemic stroke, a significant threat to human life and health, refers to a class of conditions where brain tissue damage is induced following decreased cerebral blood flow. The incidence of ischemic stroke has been steadily increasing globally, and its disease mechanisms are highly complex and involve a multitude of biological mechanisms at various scales from genes all the way to the human body system that can affect the stroke onset, progression, treatment, and prognosis. To complement conventional experimental research methods, computational systems biology modeling can integrate and describe the pathogenic mechanisms of ischemic stroke across multiple biological scales and help identify emergent modulatory principles that drive disease progression and recovery. In addition, by running virtual experiments and trials in computers, these models can efficiently predict and evaluate outcomes of different treatment methods and thereby assist clinical decision-making. In this review, we summarize the current research and application of systems-level computational modeling in the field of ischemic stroke from the multiscale mechanism-based, physics-based and omics-based perspectives and discuss how modeling-driven research frameworks can deliver insights for future stroke research and drug development.

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.

Validation of the prehospital stroke scales as a tool for in-hospital large vessel occlusion stroke: whether we satisfied?

BACKGROUND

Prehospital stroke severity scales have been widely used to identify whether community stroke patients presented with large vessel occlusion (LVO) or not. However, whether these scales are also applicable to in-hospital stroke patients remains unknown.

PURPOSE

We aim to validate and compare the predictive capability of these scales for these patients.

MATERIAL AND METHODS

From January 2016 to October 2020, a total of 243 patients who activated in-hospital stroke alerts, were included in this study. The area under the curve (AUC) was used to assess the predictive ability of five scales (Field Assessment Stroke Triage for Emergency Destination [FAST-ED], Rapid Arterial Occlusion Evaluation [RACE], Los Angeles Motor Scale [LAMS], Cincinnati Prehospital Stroke Severity Scale [CPSSS], and Prehospital Acute Stroke Severity scale [PASS]) for LVO. In addition, multivariable logistic analysis was adopted to determine the predictors of LVO in our patients cohort.

RESULTS

Finally, 94 (38.7%) patients were confirmed presence of persistent LVO. The AUC for the FAST-ED, RACE, LAMS, CPSSS, and PASS scales to predict the presence of LVO in patients activating in-hospital stroke alerts were 0.82, 0.89, 0.86, 0.81, and 0.79, respectively. After multivariable analysis, baseline NIHSS (adjusted odds ratio [OR] = 1.160, 95% confidence interval [CI] = 1.110-1.212; P < 0.001) atrial fibrillation (adjusted OR = 2.940, 95% CI = 1.387-6.230; P = 0.005) and cardiac/pulmonary procedure (adjusted OR = 6.861, 95% CI = 2.437-19.315; P < 0.001) remained independent predictors of LVO.

CONCLUSION

The prehospital stroke scales also showed good predictive capabilities in discriminating LVO among inpatients who activated stroke alerts. However, given that inpatients' history is more readily available, a specifically designed in-hospital stroke scale that combines stroke severity and history is warranted.

Neutrophil Extracellular Traps and Thrombolysis Resistance: New Insights for Targeting Therapies

BACKGROUND

Thrombosis is linked to neutrophil release of neutrophil extracellular traps (NETs). NETs are proposed as a mechanism of resistance to thrombolysis. This study intends to analyze the composition of thrombi retrieved after mechanical thrombectomy, estimate the age and organization of thrombi, and evaluate associations with the use of thrombolysis, antiplatelets, and heparin.

METHODS

This retrospective observational study involved 72 samples (44 from cerebral and 28 coronary arteries), which were stained with hematoxylin and eosin, anti-NE (neutrophil elastase) antibody, and anti-histone H2B (histone H2B) antibody, representing different components in NET formation, all detectable during the later stages of NETosis, for histochemical and digital quantification of NET content. The histological and morphological evaluations of the specimens were correlated, through univariate and mediation analyses, with clinical information and therapy administered before intervention.

RESULTS

The results demonstrated that the composition of cerebral and coronary thrombi differs, and there were significantly more lytic cerebral thrombi than coronary thrombi (66% versus 14%; P=0.005). There was a considerably higher expression of NETs in the cerebral thrombi as testified by the higher expression of H2B (P=0.031). Thrombolysis was remarkably associated with higher NE positivity (average marginal effect, 6.461 [95% CI, 0.7901-12.13]; P=0.02555), regardless of the origin of thrombi. There was no notable association between the administration of antiaggregant therapy/heparin and H2B/NE amount when adjusted for the thrombus location. Importantly, the age of the thrombus was the only independent predictor of NET content without any mediation of the thrombolytic treatment (P=0.014).

CONCLUSIONS

The age of the thrombus is the driving force for NET content, which correlates with impaired clinical outcomes. The therapy that is currently administered does not modify NET content. This study supports the need to investigate new pharmacological approaches added to thrombolysis to prevent NET formation or enhance their disruption, such as recombinant human DNase I (deoxyribonuclease I).

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.

Mechanical thrombectomy for AIS from large vessel occlusion - current trends and future perspectives

Stroke is found to be one of the global top causes of mortality and the major factor in years of life with a handicap (DALYs). Ischemic strokes contributed to nearly 70% of all strokes worldwide. For endovascular thrombectomy in acute ischemic stroke with large vessel obstruction (AIS-LVO), using stent retrievers and/or reperfusion catheters has become the gold standard of therapy. The methodology involved keyword-based search in databases like PubMed, Embase, and Google Scholar for recent publications on mechanical thrombectomy (MT), AIS, large vessel occlusion (Large Vessel Occlusion (LVO)), screening relevant articles, retrieving full texts, and synthesizing key findings on procedural advancements, patient selection, COVID-19 (coronavirus disease 2019) impact, delay effects, effectiveness, clinical outcomes, and future perspectives. Only people with substantial cerebral artery obstruction may do well from MT. This includes the distal carotid artery and the proximal middle cerebral artery (segment M1). The size of a blocked vessel and NIHSS (National Institute of Health Stroke Scale) score are directly connected. Both the 2018 and 2019 versions of the AHA/ASA (American Heart Association/American Stroke Association) Guidelines for the Early Management of Patients with Acute Ischemic Stroke contained the recommendations that cases with AIS-LVO get endovascular therapy when administered during the time frame of 0-6 h after onset (Grade IA evidence). It is questionable whether this group of patients can be managed without the need for intravenous tissue plasminogen activator at the onset. When functional independence [modified Rankin Scale (mRS) score 2] was present at long-term follow-up, the endovascular intervention was favored. Tenecteplase, which differs from alteplase in terms of genetic variation, has a greater half-life and a higher level of fibrin selectivity, enabling bolus infusion. Studies have also demonstrated its efficacy and safety, as well as its long-term cost-effectiveness.

Cranial midline shift is a predictor of the clinical prognosis of acute cerebral infarction patients undergoing emergency endovascular treatment

Endovascular treatment is widely used in acute cerebral infarction (ACI), but patient prognosis varies greatly. We aimed to investigate the predictive value of midline shift (MLS) threshold for the clinical prognosis of patients with ACI who undergo emergency endovascular treatment. We prospectively enrolled patients with ACI who received endovascular treatment within 24 h of onset. Cranial images were collected within 24 h after endovascular treatment. We assessed MLS at the level of the midbrain, pineal calcification, septum pellucida, and falx cerebri and noted the maximum MLS (MLS[max]) among these locations. Functional outcomes were assessed at 90 days using the modified Rankin Scale. Receiver operating characteristic curves and optimal cutoff points were used to analyze the predictive value of MLS. We enrolled 82 patients, including 46 with poor outcomes. Although the MLS values at all levels were significantly different between the poor and favorable outcome groups (p < 0.01), the MLS(max) tended to be a better marker for 90-day poor outcome. To predict poor outcome, the optimal cutoff values for MLS(max) within 24 and 48 h after intervention were 0.45 and 2.35 mm, respectively. MLS(max) has predictive value for patient prognosis.

Systemic immune inflammatory index is an independent predictor for the requirement of decompressive craniectomy in large artery occlusion acute ischemic stroke patients after mechanical thrombectomy

Background and purpose

Following mechanical thrombectomy (MT), patients with large artery occlusive acute ischemic stroke (LAO-AIS) often have cerebral herniation due to its complications, resulting in poor prognosis. Decompressive craniectomy (DC) can markedly improve patient prognosis. This study aimed to verify the predictive value of clinical parameters such as the systemic immune-inflammatory index (SII) for DC in patients with LAO-AIS after MT.

Methods

Clinical data of a total of 173 patients with LAO-AIS treated with MT between January 2020 and January 2022 were retrospectively analyzed. Patients receiving DC were grouped into an experimental group or a control group (no DC). The patients were randomly divided into the training set (n = 126, 75%) and validation set (n = 43, 25%). Multivariate logistic regression was used to construct a nomogram predictive model.

Results

The SII value in the experimental group (median: 2851.1×109/L) was significantly higher than that in the control group (median: 1898.6 × 109/L) (P = 0.019). Receiver operating characteristic (ROC) analyses showed that the best cutoff value of the SII was 2505.7 × 109/L with a sensitivity of 55%, a specificity of 75.8%, and an area under the curve (AUC) of 0.649. Multivariate logistic regression indicated that the SII was an independent predictor for performing DC in patients with LAO-AIS after MT (OR = 3.579, 95% CI = 1.360-9.422, P = 0.01). The AUC was 0.728 in the training set and 0.583 in the validation set. The average error of the calibration curve was 0.032 in the training set and 0.023 in the validation set. The average error was relatively small and consistent in the training set and validation set. The C-index of the nomogram was 0.804 suggesting good accuracy.

Conclusions

The SII at admission is an independent predictor for the requirement of DC in patients with LAO-AIS after MT. The SII-based nomogram helps doctors make decisions on whether DC is needed timely and rationally, and thereby may improve the prognosis of these patients.

Plasma Lipid Mediators Associate With Clinical Outcome After Successful Endovascular Thrombectomy in Patients With Acute Ischemic Stroke

Background

Neuroinflammatory response contributes to early neurological deterioration (END) and unfavorable long-term functional outcome in patients with acute ischemic stroke (AIS) who recanalized successfully by endovascular thrombectomy (EVT), but there are no reliable biomarkers for their accurate prediction. Here, we sought to determine the temporal plasma profiles of the bioactive lipid mediators lipoxin A4 (LXA4), resolvin D1 (RvD1), and leukotriene B4 (LTB4) for their associations with clinical outcome.

Methods

We quantified levels of LXA4, RvD1, and LTB4 in blood samples retrospectively and longitudinally collected from consecutive AIS patients who underwent complete angiographic recanalization by EVT at admission (pre-EVT) and 24 hrs post-EVT. The primary outcome was unfavorable long-term functional outcome, defined as a 90-day modified Rankin Scale score of 3-6. Secondary outcome was END, defined as an increase in National Institutes of Health Stroke Scale (NIHSS) score ≥4 points at 24 hrs post-EVT.

Results

Eighty-one consecutive AIS patients and 20 healthy subjects were recruited for this study. Plasma levels of LXA4, RvD1, and LTB4 were significantly increased in post-EVT samples from AIS patients, as compared to those of healthy controls. END occurred in 17 (20.99%) patients, and 38 (46.91%) had unfavorable 90-day functional outcome. Multiple logistic regression analyses demonstrated that post-EVT levels of LXA4 (adjusted odd ratio [OR] 0.992, 95% confidence interval [CI] 0.987-0.998), ΔLXA4 (adjusted OR 0.995, 95% CI 0.991-0.999), LTB4 (adjusted OR 1.003, 95% CI 1.001-1.005), ΔLTB4 (adjusted OR 1.004, 95% CI 1.002-1.006), and post-EVT LXA4/LTB4 (adjusted OR 0.023, 95% CI 0.001-0.433) and RvD1/LTB4 (adjusted OR 0.196, 95% CI 0.057-0.682) ratios independently predicted END, and post-EVT LXA4 levels (adjusted OR 0.995, 95% CI 0.992-0.999), ΔLXA4 levels (adjusted OR 0.996, 95% CI 0.993-0.999), and post-EVT LXA4/LTB4 ratio (adjusted OR 0.285, 95% CI 0.096-0.845) independently predicted unfavorable 90-day functional outcome. These were validated using receiver operating characteristic curve analyses.

Conclusions

Plasma lipid mediators measured 24 hrs post-EVT were independent predictors for early and long-term outcomes. Further studies are needed to determine their causal-effect relationship, and whether the imbalance between anti-inflammatory/pro-resolving and pro-inflammatory lipid mediators could be a potential adjunct therapeutic target.

Arterial Collapse during Thrombectomy for Stroke: Clinical Evidence and Experimental Findings in Human Brains and In Vivo Models

BACKGROUND AND PURPOSE

Aspiration thrombectomy has become a preferred approach to recanalize large-vessel occlusion in stroke with a growing trend toward using larger-bore catheters and stronger vacuum pumps. However, the mechanical response of the delicate cerebral arteries to aspiration force has not been evaluated. Here, we provide preclinical and clinical evidence of intracranial arterial collapse in aspiration thrombectomy.

MATERIALS AND METHODS

We presented a clinical case of arterial collapse with previously implanted flow diverters. We then evaluated the effect of vacuum with conventional aspiration catheters (with and without stent retrievers) in a rabbit model (n = 3) using fluoroscopy and intravascular optical coherence tomography. Then, in a validated human cadaveric brain model, we conducted 168 tests of direct aspiration thrombectomy following an experimental design modifying the catheter inner diameter (0.064 inch, 0.068 inch, and 0.070 inch), cerebral perfusion pressures (mean around 60 and 90 mm Hg), and anterior-versus-posterior circulation. Arterial wall response was recorded and graded via direct transluminal observation.

RESULTS

Arterial collapse was observed in both the patient and preclinical experimental models. In the human brain model, arterial collapse was observed in 98% of cases in the M2 and in all the cases with complete proximal flow arrest. A larger bore size of the aspiration catheter, a lower cerebral perfusion pressure, and the posterior circulation in comparison with the anterior circulation were associated with a higher probability of arterial collapse.

CONCLUSIONS

Arterial collapse does occur during aspiration thrombectomy and is more likely to happen with larger catheters, lower perfusion pressure, and smaller arteries.

Posterior Circulation Endovascular Thrombectomy for Large Vessels Occlusion in Patients Presenting with NIHSS Score ≤ 10

Mechanical thrombectomy (MT) is currently the gold standard treatment for ischemic stroke due to large vessel occlusion (LVO). However, the evidence of clinical usefulness of MT in posterior circulation LVO (pc-LVO) is still doubtful compared to the anterior circulation, especially in patients with mild neurological symptoms. The database of 10 high-volume stroke centers in Europe, including a period of three year and a half, was screened for patients with an acute basilar artery occlusion or a single dominant vertebral artery occlusion ("functional" BAO) presenting with a NIHSS ≤10, and with at least 3 months follow-up. A total of 63 patients were included. Multivariate analysis demonstrated that female gender (adjusted OR 0.04; 95% CI 0-0.84; p = 0.04) and combined technique (adj OR 0.001; 95% CI 0-0.81; p = 0.04) were predictors of worse outcome. Higher pc-ASPECTS (adj OR 4.75; 95% CI 1.33-16.94; p = 0.02) and higher Delta NIHSS (adj OR 2.06; 95% CI 1.16-3.65; p = 0.01) were predictors of better outcome. Delta NIHSS was the main predictor of good outcome at 90 days in patients with posterior circulation LVO presenting with NIHSS score ≤ 10.