Clinical characteristics of fast and slow progressors of infarct growth in anterior circulation large vessel occlusion stroke

Predictive value of CT imaging features on the risk of hemorrhagic transformation after mechanical thrombectomy for acute ischemic stroke with large vessel obstruction

OBJECTIVE

To investigate the predictive value of computer tomography (CT) imaging features for the risk of hemorrhagic transformation (HT) after mechanical thrombectomy for acute ischemic stroke with large vessel obstruction (AIS-LVO).

METHODS

A total of 135 patients with AIS-LVO diagnosed and treated in our hospital from August 2021 to May 2023 were selected as the research subjects. Their clinical data were retrospectively analyzed. Mechanical thrombectomy was performed in all patients. The patients were divided into the HT group (n = 27) and the non-HT group (n = 108) according to whether HT occurred within 24 h after thrombectomy. CT examination was performed after mechanical thrombectomy in the two groups, and the changes in CT imaging indexes in the two groups were observed. Logistic regression was used to analyze the influencing factors and a prediction model was constructed based on the influencing factors. The receiver operating characteristic (ROC) curve was established to analyze the predictive value. Additionally, ROC curve was used to analyze the diagnostic value of serum CT imaging features.

RESULTS

Compared with the non-HT group, the proportion of atrial fibrillation history in the HT group was significantly increased, and the National Institute of Health Stroke Scale (NIHSS) score and galectin-3 (Gal-3) level were significantly increased before thrombectomy (P < 0.01). Compared with the non-HT group, the proportion of exudation of contrast medium and Hyperdense Middle Cerebral Artery Sign (HMCAS) in the HT group was significantly increased, time to peak (TTP) was significantly prolonged, and cerebral blood flow (CBF) was significantly decreased (P < 0.001). The history of atrial fibrillation, NIHSS score before thrombectomy, Gal-3, contrast agent exudation, HMCAS, TTP and CBF were the influencing factors of postoperative HT after mechanical thrombectomy in AIS-LVO (P < 0.05). Based on the results of multivariate logistic regression analysis, a prediction model was established as follows: Logit (P) = -3.520 + 1.529 × history of atrial fibrillation + 0.968 × NIHSS score before thrombectomy + 0.806 × Gal-3 + 1.134 × contrast agent exudation + 2.146 × HMCAS + 0.684 × TTP-0.725 × CBF. The area under the curve (AUC) of the logistic prediction model for predicting HT after AIS-LVOLVO mechanical thrombectomy was 0.873 (95% CI 0.817-0.929) with a sensitivity of 78.75% and a specificity of 83.33%, indicating that the prediction model had good prediction efficiency. The AUC of TTP and CBF alone in predicting HT after mechanical thrombectomy in AIS-LVO patients was 0.728 and 0.736, respectively. The AUC of combined detection was 0.783, and the combined detection had a high diagnostic value for HT after mechanical thrombectomy in AIS-LVO patients.

CONCLUSION

The combined detection of TTP and CBF of CT imaging features had certain diagnostic value for HT in AIS-LVO patients after mechanical thrombectomy. The logistic prediction model based on these influencing factors had a high diagnostic value for HT after mechanical thrombectomy.

Infarct Growth in Patients with Emergent Large Vessel Occlusion Stroke Transferred for Endovascular Thrombectomy

INTRODUCTION

Patients with a large vessel occlusion (LVO) stroke who are transferred to a comprehensive stroke center (CSC) for endovascular thrombectomy (EVT) often experience infarct growth. We aimed to investigate the clinical predictors of fast infarct growth and its effect on clinical outcomes.

METHODS

We retrospectively collected EVT data of patients with LVO transferred to our center between March 14, 2019, and June 28, 2022. The absolute rate of Alberta Stroke Program Early Computed Tomography Score (ASPECTS) decay was defined as (ASPECTS primary CT - ASPECTS repeat CT)/elapsed hours. The ratio of relative ASPECTS deterioration was defined as (ASPECTS primary CT - ASPECTS repeat CT)/ASPECTS primary CT. In the primary analysis, the study population was dichotomized into absolute slow progressors and absolute fast progressors using the median absolute rate of ASPECTS decay. Secondary analysis was also conducted using the median relative ASPECTS deterioration ratio, and the study population was categorized into relative fast progressors and relative slow progressors. Favorable outcome was defined as a 90-day modified Rankin Scale (mRS) score ≤ 2.

RESULTS

We included 309 patients: median age 72 years (IQR 65-77); median National Institutes of Health Stroke Scale (NIHSS) 14 (IQR 11-18). The median absolute rate of ASPECTS decay was 0.42 points/hour and the median relative ASPECTS deterioration ratio was 11.1%. Overall, fast infarct growth was independently associated with worse 90-day outcome (absolute rate of ASPECTS decay: OR = 3.395; 95% CI 1.844-6.250; P < 0.001; relative ASPECTS deterioration ratio: OR = 3.754; 95% CI 2.050-6.873; P < 0.001). In multivariable analysis, fast infarct growth was independently associated with high admission NIHSS, proximal occlusions, and poor collateral status, while intravenous thrombolysis before transfer was negative with fast inter-hospital infarct growth.

CONCLUSIONS

For patients with LVO stroke who are transferred from a PSC to CSC for EVT, the infarct growth rate is highly variable and is strongly associated with 90-day outcomes. Initiation of intravenous bridging therapy before transfer may limit the infarct growth during inter-hospital transfer.

Cerebral Infarct Growth: Pathophysiology, Pragmatic Assessment, and Clinical Implications

Cerebral ischemic injury occurs when blood flow drops below a critical level, resulting in an energy failure. The progressive transformation of hypoperfused viable tissue, the ischemic penumbra, into infarction is a mechanism shared by patients with ischemic stroke if timely reperfusion is not achieved. Yet, the pace at which this transformation occurs, known as the infarct growth rate (IGR), exhibits remarkable heterogeneity among patients, brain regions, and over time, reflecting differences in compensatory collateral flow and ischemic tolerance. We review (1) the pathophysiology of infarct growth, (2) the advantages and pitfalls of different approaches of IGR measurement, (3) research gaps for future studies, and (4) the clinical implications of stroke progressor phenotypes. The estimated average IGR in patients with acute large vessel occlusion stroke is 5.4 mL/h although there is wide variability based on ischemic stroke subtype, occlusion location, presence of collaterals, and patient baseline status. The IGR can be calculated using various pragmatic strategies, mostly either quantifying the extension of the infarct at a particular time and dividing this measure by the time that elapsed from symptom onset to imaging assessment or by using collateral blood flow status as a radiological surrogate marker. The IGR defines a spectrum of clinical stroke phenotypes, often dichotomized into fast and slow progressors. An IGR ≥10 mL/h and the perfusion metric hypoperfusion intensity ratio ≥0.5 are commonly used definitions of fast progressors. A nuanced understanding of the IGR and stroke progressor phenotypes could have clinical implications, including informing prognostication, acute decision-making in peripheral-to-comprehensive transfer patients eligible for thrombectomy, and selection for adjuvant neuroprotective agents.

Association of renal biomarkers with fast progressor phenotype and related outcomes in anterior circulation large vessel occlusion stroke

Background

Renal dysfunction is a known predictor of long-term functional dependency after anterior circulation large vessel occlusion (ACLVO) stroke. However, the impact of renal dysfunction on early infarct growth rate (IGR) has not been previously demonstrated. The objective of this study was to define the association of creatinine-based renal biomarkers with fast or slow progressor phenotypes and related clinical outcomes in ACLVO stroke.

Methods

This retrospective study examined patients with acute intracranial internal carotid artery or middle cerebral artery-M1 occlusions admitted between 2014 and 2019. Patients were included if they received baseline CT perfusion (CTP) or MRI on presentation within 24 h of estimated stroke onset. Infarct growth rate (IGR) was determined by ischemic core volume on CTP or MRI divided by time from stroke onset to imaging. IGR was used to stratify fast progressor (IGR ≥10 mL/h) and slow progressor (IGR < 10 mL/h) status. Renal dysfunction was assessed based on serum creatinine and estimated glomerular filtration rate (eGFR) on presenting laboratories. Logistic regression models, adjusted for significant covariates, identified independent associations between renal dysfunction biomarkers, progressor status, and clinical outcomes based on modified Rankin Scale (mRS) at 90 days.

Results

Among 230 patients with ACLVO, 29% were fast progressors, with median serum creatinine levels higher than slow progressors (1.1 vs. 0.9 mg/dL, p < 0.05) and lower median eGFR (66.2 vs. 69.0 mL/min/1.73m2, p < 0.05). Elevated creatinine (≥1.2 mg/dL) was independently associated with fast progressor status (adjusted OR 2.37, 95% CI 1.18-4.77), worse 90-day mRS (adjusted OR 1.88, 95% CI 1.01-3.51) and mortality (adjusted OR 2.57, 95% CI 1.14-5.79). Reduced eGFR (<60 mL/min/1.73m2) was independently associated with fast progressor status (adjusted OR 2.38, 95% CI 1.14-4.94), but not with 90-day mRS or mortality.

Conclusion

Serum creatinine-based biomarkers of renal dysfunction were associated with fast progressor phenotype of ACLVO stroke, and worse clinical outcomes, which may help identify such patients earlier during emergency evaluation for expedited access to EVT. Future prospective studies are warranted to confirm and test implementation of these findings.

Safety and efficacy of endovascular recanalization in patients with mild anterior stroke due to large-vessel occlusion exceeding 24 hours

BACKGROUND

Endovascular recanalization (ER) has demonstrated efficacy as a treatment modality for patients presenting with acute ischemic stroke (AIS) caused by large-vessel occlusion (LVO) within a 24-hour timeframe. Nevertheless, the safety and effectiveness of ER in patients with a time of onset exceeding 24 h remain uncertain.

OBJECTIVE

To evaluate the safety and efficacy of ER treatment for mild ischemic stroke beyond 24-h from symptom onset.

METHODS

A retrospectively maintained database of mild AIS due to LVO from March2018 to September 2022 at a comprehensive stroke center was screened.Patients received ER or standard medical therapies (SMT) for anterior circulation AIS due to LVO > 24-h were selected.

RESULTS

We included 47 LVO patients with mild AIS beyond 24-h who suffered neurological deterioration (ND). 34 of these patients underwent ER, the other 13 received SMT. The technical success rate of recanalization was 82.4% (28/34). Patients received ER had significantly lower NIHSS score at discharge and 90-day mRS score (p = 0.028, p = 0.037, respectively) compared to SMT. In addition, they had significantly lower 90-day recurrence of ischemic stroke and lower incidence of moderate-severe stroke (with a NIHSS score at least 5) (p = 0.037, p = 0.033). There were 4 patients (11.7%) had perioperative complications, and no symptomatic intracranial hemorrhage occurred.

CONCLUSION

ER treatment for mild AIS due to LVO encountered ND was generally safe and effective, even beyond 24-h, and resulted in a good prognosis and lower 90-day recurrence compared to SMT.

Dynamic Evolution of Infarct Volumes at MRI in Ischemic Stroke Due to Large Vessel Occlusion

BACKGROUND AND OBJECTIVES

The typical infarct volume trajectories in stroke patients, categorized as slow or fast progressors, remain largely unknown. This study aimed to reveal the characteristic spatiotemporal evolutions of infarct volumes caused by large vessel occlusion (LVO) and show that such growth charts help anticipate clinical outcomes.

METHODS

We conducted a secondary analysis from prospectively collected databases (FRAME, 2017-2019; ETIS, 2015-2022). We selected acute MRI data from anterior LVO stroke patients with witnessed onset, which were divided into training and independent validation datasets. In the training dataset, using Gaussian mixture analysis, we classified the patients into 3 growth groups based on their rate of infarct growth (diffusion volume/time-to-imaging). Subsequently, we extrapolated pseudo-longitudinal models of infarct growth for each group and generated sequential frequency maps to highlight the spatial distribution of infarct growth. We used these charts to attribute a growth group to the independent patients from the validation dataset. We compared their 3-month modified Rankin scale (mRS) with the predicted values based on a multivariable regression model from the training dataset that used growth group as an independent variable.

RESULTS

We included 804 patients (median age 73.0 years [interquartile range 61.2-82.0 years]; 409 men). The training dataset revealed nonsupervised clustering into 11% (74/703) slow, 62% (437/703) intermediate, and 27% (192/703) fast progressors. Infarct volume evolutions were best fitted with a linear (r = 0.809; p < 0.001), cubic (r = 0.471; p < 0.001), and power (r = 0.63; p < 0.001) function for the slow, intermediate, and fast progressors, respectively. Notably, the deep nuclei and insular cortex were rapidly affected in the intermediate and fast groups with further cortical involvement in the fast group. The variable growth group significantly predicted the 3-month mRS (multivariate odds ratio 0.51; 95% CI 0.37-0.72, p < 0.0001) in the training dataset, yielding a mean area under the receiver operating characteristic curve of 0.78 (95% CI 0.66-0.88) in the independent validation dataset.

DISCUSSION

We revealed spatiotemporal archetype dynamic evolutions following LVO stroke according to 3 growth phenotypes called slow, intermediate, and fast progressors, providing insight into anticipating clinical outcome. We expect this could help in designing neuroprotective trials aiming at modulating infarct growth before EVT.

Review of Cerebral Collateral Circulation and Insight into Cardiovascular Strategies to Limit Collateral Damage in Ischemic Stroke

Cerebral collateral circulation is a dynamic and adaptive process by which alternative vascular pathways supply perfusion to ischemic brain tissue in the event of an arterial occlusion. This complicated network of blood vessels that acts as a natural bypass plays a pivotal role in stroke pathophysiology and has become a key area of study given its significance in stroke treatment and patient outcomes. In this review, we will study the factors influencing the formation, recruitment, and endurance of collateral vessels; discuss imaging modalities for quantitative and qualitative assessment of this network; explore the role of collaterals in stroke management; and highlight several cardiovascular strategies to minimize damage to collaterals and optimize stroke outcomes.

Hi1a Improves Sensorimotor Deficit following Endothelin-1-Induced Stroke in Rats but Does Not Improve Functional Outcomes following Filament-Induced Stroke in Mice

Activation of acid-sensing ion channel 1a (ASIC1a) plays a major role in mediating acidosis-induced neuronal injury following a stroke. Therefore, the inhibition of ASIC1a is a potential therapeutic avenue for the treatment of stroke. Venom-peptide Hi1a, a selective and highly potent ASIC1a inhibitor, reduces the infarct size and functional deficits when injected into the brain after stroke in rodents. However, its efficacy when administered using a clinically relevant route of administration remains to be established. Therefore, the current investigation aims to examine the efficacy of systemically administered Hi1a, using two different models of stroke in different species. Mice were subjected to the filament model of middle cerebral artery occlusion (MCAO) and treated with Hi1a systemically using either a single- or multiple-dosing regimen. 24 h poststroke, mice underwent functional testing, and the brain infarct size was assessed. Rats were subjected to endothelin-1 (ET-1)-induced MCAO and treated with Hi1a intravenously 2 h poststroke. Rats underwent functional tests prior to and for 3 days poststroke, when infarct volume was assessed. Mice receiving Hi1a did not show any improvements in functional outcomes, despite a trend toward reduced infarct size. This trend for reduced infarct size in mice was consistent regardless of the dosing regimen. There was also a trend toward lower infarct size in rats treated with Hi1a. More specifically, Hi1a reduced the amount of damage occurring within the somatosensory cortex, which was associated with an improved sensorimotor function in Hi1a-treated rats. Thus, this study suggests that Hi1a or more brain-permeable ASIC1a inhibitors are a potential stroke treatment.

Interaction between intravenous thrombolysis and clinical outcome between slow and fast progressors undergoing mechanical thrombectomy: a post-hoc analysis of the SWIFT-DIRECT trial

BACKGROUND

In proximal occlusions, the effect of reperfusion therapies may differ between slow or fast progressors. We investigated the effect of intravenous thrombolysis (IVT) (with alteplase) plus mechanical thrombectomy (MT) versus thrombectomy alone among slow versus fast stroke progressors.

METHODS

The SWIFT-DIRECT trial data were analyzed: 408 patients randomized to IVT+MT or MT alone. Infarct growth speed was defined by the number of points of decay in the initial Alberta Stroke Program Early CT Score (ASPECTS) divided by the onset-to-imaging time. The primary endpoint was 3-month functional independence (modified Rankin scale 0-2). In the primary analysis, the study population was dichotomized into slow and fast progressors using median infarct growth velocity. Secondary analysis was also conducted using quartiles of ASPECTS decay.

RESULTS

We included 376 patients: 191 IVT+MT, 185 MT alone; median age 73 years (IQR 65-81); median initial National Institutes of Health Stroke Scale (NIHSS) 17 (IQR 13-20). The median infarct growth velocity was 1.2 points/hour. Overall, we did not observe a significant interaction between the infarct growth speed and the allocation to either randomization group on the odds of favourable outcome (P=0.68). In the IVT+MT group, odds of any intracranial hemorrhage (ICH) were significantly lower in slow progressors (22.8% vs 36.4%; OR 0.52, 95% CI 0.27 to 0.98) and higher among fast progressors (49.4% vs 26.8%; OR 2.62, 95% CI 1.42 to 4.82) (P value for interaction <0.001). Similar results were observed in secondary analyses.

CONCLUSION

In this SWIFT-DIRECT subanalysis, we did not find evidence for a significant interaction of the velocity of infarct growth on the odds of favourable outcome according to treatment by MT alone or combined IVT+MT. However, prior IVT was associated with significantly reduced occurrence of any ICH among slow progressors whereas this was increased in fast progressors.

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

Introduction

Cerebral collateral circulation has a central role in ischemic stroke pathophysiology, and it is considered to correlate with infarct size, the success of reperfusion therapies, and clinical outcomes. Our aim was to study the factors influencing the development of collaterals in patients with acute ischemic stroke eligible for endovascular treatment.

Materials and methods

We enrolled patients with acute ischemic stroke and large vessel occlusion of anterior circulation potentially eligible for endovascular treatment. Included patients performed multiphase CT angiography to assess collaterals that were graded by the Menon Grading Score. We investigated the associations between clinical factors and collaterals and tested independent associations with logistic (good vs. poor collaterals) and ordinal (collateral grade grouped, Menon 0-2, 3, 4-5) regression analysis adjusting for age, sex, stroke severity, and onset to CT time (OCTT).

Results

We included 520 patients, the mean age was 75 (±13.6) years, 215 (41%) were men, and the median (IQR) NIHSS was 17 (11-22). Good collaterals were present in 323 (62%) patients and were associated with lower NIHSS (median 16 vs. 18; p < 0.001) and left hemisphere involvement (60% vs. 45%; p < 0.001), whereas previous stroke/TIA was more frequent in patients with poor collaterals (17 vs. 26%; p = 0.014). These results were confirmed in both logistic and ordinal regression analyses where good collaterals were associated with lower NIHSS (OR = 0.94; 95% CI = 0.91-0.96; cOR = 0.95; 95% CI = 0.92-0.97, respectively) and left hemisphere stroke (OR = 2.24; 95% CI = 1.52-3.28; cOR = 2.11; 95% CI = 1.46-3.05, respectively), while previous stroke/TIA was associated with poor collaterals (OR = 0.57; 95% CI = 0.36-0.90; cOR = 0.61; 95% CI = 0.40-0.94, respectively). Vascular risk factors, demographics, and pre-stroke treatments did not influence the collateral score.

Discussion

The results of our study suggest that risk factors and demographics do not influence the development of collateral circles, except for a negative relation with previous ischemic events. We confirm an already reported observation of a possible protective effect of collaterals on tissue damage assuming NIHSS as its surrogate. The association between left hemispheric stroke and better collaterals deserves to be further explored. Further efforts are needed to identify the factors that favor the development of collaterals.

Collateral Blood Flow and Ischemic Core Growth

Treatment of a large vessel occlusion in the acute ischemic stroke setting focuses on vessel recanalization, and endovascular thrombectomy results in favorable outcomes in appropriate candidates. Expeditious treatment is imperative, but patients often present to institutions that do not have neurointerventional surgeons and need to be transferred to a comprehensive stroke center. These treatment delays are common, and it is important to identify factors that mitigate the progression of the ischemic core in order to maximize the preservation of salvageable brain tissue. Collateral blood flow is the strongest factor known to influence ischemic core growth, which includes the input arterial vessels, tissue-level vessels, and venous outflow. Collateral blood flow at these different levels may be imaged by specific imaging techniques that may also predict ischemic core growth during treatment delays and help identify patients who would benefit from transfer and endovascular therapy, as well as identify those patients in whom transfer may be futile. Here we review collateral blood flow and its relationship to ischemic core growth in stroke patients.