Determinants of cerebral collateral circulation in acute ischemic stroke due to large vessel occlusion

Automated assessment of collateral circulation and infarct core: predictors of functional outcomes in acute ischemic stroke following endovascular thrombectomy

PURPOSE

This study aimed to evaluate the predictive value of automatically assessed collateral circulation (CC) and infarct core for functional outcome in acute ischemic stroke (AIS) patients treated with endovascular thrombectomy (EVT).

METHODS

We conducted a retrospective cohort study of 208 patients with anterior large vessel occlusion treated with EVT. Two AI-powered software were used to automatically assess CC and infarct core. Comparative analyses included patient demographics, clinical and imaging data, and functional outcome. Univariate and multivariable logistic regression analyses were conducted to predict the 90-day functional outcome. A favorable outcome was defined as a modified Rankin scale (mRS) score ≤ 2.

RESULTS

Among the 208 patients, 114 (54.8%) were women and 94 were men, with a mean age of 71.4 ± 13.3 years. Patients with higher collateral score (CS) exhibited lower infarct core volumes (p < 0.001) and better mRS score at 90 days (p = 0.008). Among patients with a favorable outcome, the mean infarct core volume was lower compared to those with poor outcomes (5 mL vs. 8.6 mL, p = 0.003). In univariate logistic regression, both infarct core (OR 0.94, p = 0.005) and CS (OR 1.84, p = 0.014) were predictors of favorable outcome. However, in multivariable models, only infarct core remained a significant independent predictor [AORs of 0.95 (p = 0.021) and 0.96 (p = 0.039)].

CONCLUSION

Automatically assessed infarct core is a robust predictor of functional outcome in AIS patients post-EVT, while CS's predictive value diminishes when adjusted for infarct core. These findings support the integration of AI-powered evaluations in clinical settings to improve prognosis and treatment strategies for AIS.

Evaluation of contralateral arterial flow compensation using transcranial Doppler in acute internal carotid artery occlusion and implications for neurological outcome

Acute internal carotid artery occlusion (AICAO) can result in malignant cerebral edema and unfavorable patient outcomes. This study evaluated the utility of transcranial Doppler (TCD) in assessing contralateral flow compensation and predicting outcomes in patients with AICAO. We enrolled 51 patients within 6 h of symptom onset and conducted TCD examinations to evaluate collateral circulation. Among the 51 patients, 40 (78.4%) had collateral flow. TCD showed excellent agreement with magnetic resonance angiography (MRA)/CT angiography (CTA) in assessing anterior communicating artery (ACoA) status (kappa = 0.873, p < 0.001). Our findings indicated that the absence of collaterals (OR = 7.649, p = 0.032), younger age (OR = 0.907, p = 0.048), and lower Alberta Stroke Program Early CT Score 24 h after onset (ASPECTs1) (OR = 0.276, p = 0.025) were independent predictors of malignant cerebral edema. Additionally, advanced age, elevated National Institutes of Health Stroke Scale Score (NIHSSs) in the Emergency Department, sole extracranial-to-intracranial collateral circulation (EICC), and absence ACoA were independently associated with worse outcomes (all p < 0.05). In conclusion, TCD evaluation of collateral circulation in AICAO patients can effectively predict the risk of malignant cerebral edema, with ACoA presence correlating with favorable outcomes and sole EICC linked to poorer prognosis. While age, NIHSSs and ASPECTs also contribute, TCD's assessment of collaterals provides key insights for patient management.

Determinants of Leptomeningeal Collateral Status in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

Leptomeningeal collateral status is a major determinant of outcomes in patients with acute ischemic stroke; however, the factors that determine collateral status are not well understood. We conducted a comprehensive systematic review and meta-analysis to identify determinants associated with collateral status in patients with anterior circulation infarction.

METHODS AND RESULTS

The PubMed, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials databases were searched for studies that reported the determinants of leptomeningeal collateral status in acute ischemic stroke between January 2000 and June 2023. A random-effects meta-analysis model was used to pool the determinants of leptomeningeal collateral status. Eighty-one studies with 17 366 patients met the inclusion criteria. We analyzed 31 potential risk factors, and the results indicated that worse leptomeningeal collateral status was significantly associated with older age (weighted mean difference, 1.22 [95% CI, 0.69 to 1.76]), male sex (odds ratio [OR], 1.12 [95% CI, 1.02 to 1.23]), hypertension (OR, 1.27 [95% CI, 1.15 to 1.40]), diabetes (OR, 1.21 [95% CI, 1.10 to 1.33]), atrial fibrillation (OR, 1.26 [95% CI, 1.09 to 1.46]), cardioembolic stroke (OR, 1.27 [95% CI, 1.04 to 1.55]), internal carotid artery occlusion (OR, 1.84 [95% CI, 1.50 to 2.25]), and higher admission blood glucose (weighted mean difference, 8.74 [95% CI, 2.52 to 18.51]).

CONCLUSIONS

Hypertension and diabetes could be modifiable risk factors associated with leptomeningeal collateral status. Older age and male sex could be nonmodified risk factors. Further high-quality therapeutic studies focusing on controlling risk factors are needed to support our findings.

Association between heart failure and cerebral collateral flow in large vessel occlusive ischemic stroke

BACKGROUND

Cerebral collateral circulation plays a crucial role in determining the extent of brain ischemia in large vessel occlusive (LVO) stroke. Heart failure (HF) is known to cause cerebral hypoperfusion, yet the relationship between HF and robustness of collateral flow has not been well described.

METHODS

Consecutive patients with middle cerebral and/or internal carotid LVO who underwent endovascular thrombectomy (EVT) between 2012 and 2020 were included. Single-phase head CTA prior to EVT was used to assess collateral status (poor <50 % filling; good ≥50 %). Classification of HF by left ventricular ejection fraction (LVEF) on echocardiogram was used where HF with reduced ejection fraction (HFrEF) had LVEF ≤40 %, HF with preserved EF (HFpEF) had LVEF ≥50 % with evidence of structural heart disease, and no HF had LVEF≥50 % without structural heart disease. Multivariable logistic regression analyses were performed to evaluate the association between HF and poor collaterals.

RESULTS

We identified 235 patients, mean age was 69 ± 15 years; initial NIHSS was 18 ± 7. Of these, 107 (45.5 %) had HF and 105 (44.7 %) had poor collaterals. Those with HF were likely to have poor collaterals compared to those without HF (56.1 % vs 35.2 %, P = 0.001). There was a dose-dependent relationship between EF and poor collaterals: adjusted odds of poor collaterals were 1.63 and 2.45 in HFpEF and HFrEF, compared to those without HF (trend P = .018).

CONCLUSION

Patients with HFrEF are more likely to have poor cerebral collaterals. Further study is needed to explore the pathomechanisms. Optimization of HF may improve cerebral collaterals and enhance EVT outcomes.

Recruitment of pial collaterals and carotid occlusive disease in large-vessel occlusion ischemic stroke

Background and purpose

Despite the fundamental role of pial collateral vessels in limiting the progression of ischemic tissue injury in acute stroke with large vessel occlusion (LVO), in addition to the fact that collateral vessel abundance varies naturally from person to person for genetic reasons, there is limited knowledge regarding potential factors contributing to inherent interindividual variation in pial collateral supply. As it has been repeatedly hypothesized that chronic carotid occlusive disease may favor pial collateralization, we aimed to investigate the association between quantitatively assessed leptomeningeal collateral supply and pre-existing carotid stenosis in patients with acute stroke due to LVO.

Materials and methods

Patients with proximal middle cerebral artery (MCA) occlusion with or without additional internal carotid artery (ICA) occlusion were included. The degree of collateral supply was quantitatively assessed based on signal variance in T2*-weighted time series in perfusion-weighted magnetic resonance imaging (PWI). Patients were stratified into two groups according to quantitative collateral status (poor and fair to good collateral supply). The prevalence of high-grade ICA stenosis (≥70%) was evaluated in both groups.

Results

A total of 98 patients (mean age 68.8 ± 16.1 years, n = 52 (53.1%) of whom were female individuals) with MCA and/or ICA occlusion were included in the final analysis. Out of these patients, 42 had poor collateral supply, while 56 exhibited fair to good collateral supply. Additionally, 18 patients showed ipsilateral high-grade ICA stenosis. After classifying the entire cohort based on their collateral status (poor vs. fair to good collateral supply), there was no significant difference in the proportion of the patients with ipsilateral high-grade ICA stenosis between the two groups. Specifically, 6 (14.3%) patients had poor collateral supply, and 12 (21.1%) patients had fair to good collateral supply. The odds ratio (OR) was 1.58, with a 95% confidence interval (CI) of 0.490-5.685 and the p-value of 0.440. In the entire patient cohort, signal variance-based collateral supply was significantly correlated with initial stroke severity (r = -0.360, p < 0.001), baseline ischemic core volume (r = -0.362, p < 0.001), and functional outcomes (score on the modified Rankin Scale) at discharge (r = -0.367, p < 0.01).

Conclusion

In this study, we performed a quantitative and observer-independent MRI-based collateral assessment in patients with LVO. We found no significant difference in the prevalence of pre-existing high-grade ICA stenosis between patients with fair to good collateral supply and those with poor collateral supply. The potential influence of demographic and clinical variables on pial collateral supply in patients with acute stroke warrants further exploration in future studies. MRI-based collateral supply is significantly related to initial stroke severity, ischemic core volume, and early functional outcomes.

The Los Angeles motor scale (LAMS) and ASPECTS score are independently associated with DSA ASITN collateral score

BACKGROUND

Mechanical thrombectomy (MT) is the treatment standard in eligible patients with acute ischemic stroke (AIS) secondary to large vessel occlusions (LVO). Studies have shown that good collateral status is a strong predictor of MT efficacy, thus making collateral status important to quickly assess. The Los Angeles Motor Scale is a clinically validated tool for identifying LVO in the field. The aim of this study is to investigate whether admission LAMS score is also associated with the American Society of Interventional and Therapeutic Neuroradiology (ASITN) collateral score on digital subtraction angiography (DSA).

METHODS

We conducted a retrospective multicenter cohort study of consecutive patients presenting with AIS caused by LVO from 9/1/2017 to 10/1/2023 with diagnostically adequate DSA imaging. Demographic, clinical, and imaging data was collected through manual chart review. Both univariate and multivariate analysis were applied to assess associations. A p-value <0.05 was considered significant.

RESULTS

A total of 308 patients (median age: 68, IQR: 57.5-77) were included in the study. On multivariate logistic regression analysis, we found that lower admission LAMS score (adjusted OR: 0.82, 95% CI: 0.68-0.98, p < 0.05) and higher ASPECTS score (adjusted OR: 1.21, 95% CI: 1.02-1.42, p < 0.05) were independently associated with good DSA ASITN collateral score of 3-4.

CONCLUSIONS

Admission LAMS and ASPECTS score are both independently associated with DSA ASITN collateral score. This demonstrates the capability of LAMS to act as a surrogate marker of CS in the field.

Lower admission stroke severity is associated with good collateral status in distal medium vessel occlusion stroke

BACKGROUND AND PURPOSE

Distal medium vessel occlusions (DMVOs) are a significant contributor to acute ischemic stroke (AIS), with collateral status (CS) playing a pivotal role in modulating ischemic damage progression. We aimed to explore baseline characteristics associated with CS in AIS-DMVO.

METHODS

This retrospective analysis of a prospectively collected database enrolled 130 AIS-DMVO patients from two comprehensive stroke centers. Baseline characteristics, including patient demographics, admission National Institutes of Health Stroke Scale (NIHSS) score, admission Los Angeles Motor Scale (LAMS) score, and co-morbidities, including hypertension, hyperlipidemia, diabetes, coronary artery disease, atrial fibrillation, and history of transient ischemic attack or stroke, were collected. The analysis was dichotomized to good CS, reflected by hypoperfusion index ratio (HIR) <.3, versus poor CS, reflected by HIR ≥.3.

RESULTS

Good CS was observed in 34% of the patients. As to the occluded location, 43.8% occurred in proximal M2, 16.9% in mid M2, 35.4% in more distal middle cerebral artery, and 3.8% in distal anterior cerebral artery. In multivariate logistic analysis, a lower NIHSS score and a lower LAMS score were both independently associated with a good CS (odds ratio [OR]: 0.88, 95% confidence interval [CI]: 0.82-0.95, p < .001 and OR: 0.77, 95% CI: 0.62-0.96, p = .018, respectively). Patients with poor CS were more likely to manifest as moderate to severe stroke (29.1% vs. 4.5%, p < .001), while patients with good CS had a significantly higher chance of having a minor stroke clinically (40.9% vs. 12.8%, p < .001).

CONCLUSIONS

CS remains an important determinant in the severity of AIS-DMVO. Collateral enhancement strategies may be a worthwhile pursuit in AIS-DMVO patients with more severe initial stroke presentation, which can be swiftly identified by the concise LAMS and serves as a proxy for underlying poor CS.

Communicating Arteries and Leptomeningeal Collaterals: A Synergistic but Independent Effect on Patient Outcomes after Stroke

The collateral system is a compensatory mechanism activated in the acute phase of an ischemic stroke. It increases brain perfusion to the hypoperfused area. Arteries of the Willis' circle supply antegrade blood flow, while pial (leptomeningeal) arteries direct blood via retrograde flow. The aim of our retrospective study was to investigate the relationship between both collateral systems, computed tomography perfusion (CTP) values, and functional outcomes in acute stroke patients. Overall, 158 patients with anterior circulation stroke who underwent mechanical thrombectomy were included in the study. We analyzed the presence of communicating arteries and leptomeningeal arteries on computed tomography angiography. Patients were divided into three groups according to their collateral status. The main outcomes were the rate of functional independence 3 months after stroke (modified Rankin scale score, mRS) and mortality rate. Our study suggests that the collateral status, as indicated by the three groups (unfavorable, intermediate, and favorable), is linked to CT perfusion parameters, potential recuperation ratio, and stroke outcomes. Patients with favorable collateral status exhibited smaller core infarct and penumbra volumes, higher mismatch ratios, better potential for recuperation, and improved functional outcomes compared to patients with unfavorable or intermediate collateral status.

Pretreatment CT perfusion collateral parameters correlate with penumbra salvage in middle cerebral artery occlusion

BACKGROUND AND PURPOSE

Acute ischemic stroke due to large vessel occlusion (AIS-LVO) is a major cause of functional dependence. Collateral status (CS) is an important determinant of functional outcomes. Pretreatment CT perfusion (CTP) parameters serve as reliable surrogates of CS. Penumbra Salvage Index (PSI) is another parameter predictive of functional outcomes in AIS-LVO. The aim of this study is to assess the relationship of pretreatment CTP parameters with PSI.

METHODS

In this prospectively collected, retrospectively reviewed multicenter analysis, inclusion criteria were as follows: (1) CT angiography confirmed middle cerebral artery (MCA) M1-segment and proximal M2-segment occlusion from 9/1/2017 to 9/22/2022; (2) diagnostic CTP; and (3) available diagnostic Magnetic resonance Imaging (MRI) diffusion-weighted images. Pearson correlation analysis was performed to assess the association between cerebral blood volume (CBV) index and hypoperfusion intensity ratio (HIR) with PSI. p value ≤.05 was considered statistically significant.

RESULTS

In total, 131 patients (n = 86, M1 and n = 45, proximal M2 occlusion) met our inclusion criteria. CBV index showed a modest positive correlation with PSI (r = 0.34, p<.001) in patients with proximal MCA occlusion. Similar trends were noted in subgroup analysis of patients with M1 occlusion, and proximal M2 occlusion. Whereas, HIR did not have a strong trend or correlation with PSI.

CONCLUSION

CBV index correlates with PSI, whereas HIR does not. Future studies are needed to expand our understanding of the adjunct role of CBV index with other similar pretreatment CTP-based markers in clinical evaluation and decision-making in patients with MCA occlusion.

Predictors of mTICI 2c/3 over 2b in patients successfully recanalized with mechanical thrombectomy

OBJECTIVE

For patients presenting with acute ischemic stroke (AIS) caused by large vessel occlusions (LVO), mechanical thrombectomy (MT) is the treatment standard of care in eligible patients. Modified Thrombolysis in Cerebral Infarction (mTICI) grades of 2b, 2c, and 3 are all considered successful reperfusion; however, recent studies have shown achieving mTICI 2c/3 leads to better outcomes than mTICI 2b. This study aims to investigate whether any baseline preprocedural or periprocedural parameters are predictive of achieving mTICI 2c/3 in successfully recanalized LVO patients.

METHODS

We conducted a retrospective multicenter cohort study of consecutive patients presenting with AIS caused by a LVO from 1 January 2017 to 1 January 2023. Baseline and procedural data were collected through chart review. Univariate and multivariate analysis were applied to determine significant predictors of mTICI 2c/3.

RESULTS

A total of 216 patients were included in the study, with 159 (73.6%) achieving mTICI 2c/3 recanalization and 57 (26.4%) achieving mTICI 2b recanalization. We found that a higher groin puncture to first pass time (OR = 0.976, 95%CI: 0.960-0.992, p = 0.004), a higher first pass to recanalization time (OR = 0.985, 95%CI: 0.972-0.998, p = 0.029), a higher admission NIHSS (OR = 0.949, 95%CI: 0.904-0.995, p = 0.031), and a lower age (OR = 1.032, 95%CI: 1.01-1.055, p = 0.005) were associated with a decreased probability of achieving mTICI 2c/3.

INTERPRETATION

A lower groin puncture to first pass time, a lower first pass to recanalization time, a lower admission NIHSS, and a higher age were independent predictors of mTICI 2c/3 recanalization.

The Compensation Index Is Better Associated with DSA ASITN Collateral Score Compared to the Cerebral Blood Volume Index and Hypoperfusion Intensity Ratio

BACKGROUND

Pretreatment CT Perfusion (CTP) parameters serve as reliable surrogates of collateral status (CS). In this study, we aim to assess the relationship between the novel compensation index (CI, Tmax > 4 s/Tmax > 6 s) and already established CTP collateral markers, namely cerebral blood volume (CBV) index and Hypoperfusion Intensity Ratio (HIR), with the reference standard American Society of Interventional and Therapeutic Neuroradiology (ASITN) collateral score (CS) on DSA.

METHODS

In this retrospective study, inclusion criteria were the following: (a) CT angiography confirmed anterior circulation large vessel occlusion from 9 January 2017 to 10 January 2023; (b) diagnostic CT perfusion; and (c) underwent mechanical thrombectomy with documented DSA-CS. Student t-test, Mann-Whitney-U-test and Chi-square test were used to assess differences. Spearman's rank correlation and logistic regression analysis were used to assess associations. p ≤ 0.05 was considered significant.

RESULTS

In total, 223 patients (mean age: 67.8 ± 15.8, 56% female) met our inclusion criteria. The CI (ρ = 0.37, p < 0.001) and HIR (ρ = -0.29, p < 0.001) significantly correlated with DSA-CS. Whereas the CBV Index (ρ = 0.1, p > 0.05) did not correlate with DSA-CS. On multivariate logistic regression analysis taking into account age, sex, ASPECTS, tPA, premorbid mRS, NIH stroke scale, prior history of TIA, stroke, atrial fibrillation, diabetes mellitus, hyperlipidemia, heart disease and hypertension, only CI was not found to be independently associated with DSA-CS (adjusted OR = 1.387, 95% CI: 1.09-1.77, p < 0.01).

CONCLUSION

CI demonstrates a stronger correlation with DSA-CS compared to both the HIR and CBV Index where it may show promise as an additional quantitative pretreatment CS biomarker.