Time to Endovascular Reperfusion and Outcome in Acute Ischemic Stroke : A Nationwide Prospective Registry in China

Long term outcome after endovascular treatment for large ischemic core acute stroke is associated with hypoperfusion intensity ratio and onset-to-reperfusion time

BACKGROUND

Endovascular treatment (EVT) is effective for large vessel occlusion (LVO) stroke with smaller volumes of CT perfusion (CTP)-defined core. However, the influence of perfusion imaging during thrombectomy on the functional outcomes of patients with large ischemic core (LIC) stroke at both early and late time windows is uncertain in real-world practice.

METHOD

A retrospective analysis was performed on 99 patients who underwent computed tomography angiography (CTA) and CT perfusion (CTP)-Rapid Processing of Perfusion and Diffusion (RAPID) before EVT and had a baseline ischemic core ≥ 50 mL and/or Alberta Stroke Program Early CT Score (ASPECTS) score of 0-5. The primary outcome was the three-month modified Rankin Scale (mRS) score. Data were analyzed by binary logistic regression and receiver operating characteristic (ROC) curves.

RESULTS

A fair outcome (mRS, 0-3) was found in 34 of the 99 patients while 65 had a poor prognosis (mRS, 4-6). The multivariate logistic regression analysis showed that onset-to-reperfusion (OTR) time (odds ratio [OR], 1.004; 95% confidence interval [CI], 1.001-1.007; p = 0.008), ischemic core (OR, 1.066; 95% CI, 1.024-1.111; p = 0.008), and the hypoperfusion intensity ratio (HIR) (OR, 70.898; 95% CI, 1.130-4450.152; p = 0.044) were independent predictors of outcome. The combined results of ischemic core, HIR, and OTR time showed good performance with an area under the ROC curve (AUC) of 0.937, significantly higher than the individual variables (p < 0.05) using DeLong's test.

CONCLUSIONS

Higher HIR and longer OTR time in large core stroke patients were independently associated with unfavorable three-month outcomes after EVT.

Impacts of futile reperfusion and reperfusion injury in acute ischemic stroke

Acute ischemic stroke (AIS) remains to be a challenging cerebrovascular disease. The mainstay of AIS management is endovascular reperfusion therapy, including thrombectomy and thrombolysis. However, ineffective (futile) reperfusion (FR) or reperfusion injury (RI) can be seen in a significant number of patients undergoing reperfusion strategy. In this article, we discuss two clinically relevant concepts known as "time window" and "tissue window" that can impact the clinical outcome of reperfusion therapy. We also explore patient risk factors, leading to FR and RI as well as an emerging concept of "no-reflow phenomenon" seen in ineffective reperfusion. These fundamental concepts provide insight into the clinical management of AIS patients and provide references for future research.

Comparison of clinical outcomes in patients with acute ischemic stroke who underwent endovascular treatment using different perfusion modalities: a real-world multicenter study

Background

Advanced perfusion modalities are increasingly popular for various diseases. However, few studies have focused on contrasting perfusion patterns.

Objective

This study aimed to compare the time efficiency and clinical outcomes of patients with acute ischemic stroke (AIS) who underwent endovascular treatment (EVT) before one-stop arterial spin labeling (ASL) and computed tomography perfusion (CTP) protocols.

Methods

This study retrospectively included 326 patients with AIS who had accepted EVT within 24 h of onset from four comprehensive stroke centers between October 2017 and September 2022. After 1:1 matching of the propensity scores, 202 patients were separated into two groups: the ASL group (n = 101) and the CTP group (n = 101).

Results

Functional independence at 90 days (modified Rankin Scale [mRS] 0-2; p = 0.574), onset-to-puncture time (p = 0.231), door-to-puncture time (p = 0.136), and door-to-perfusion time (p = 0.646) were not significantly different between the two groups. The proportion of EVT complications (31.7% in the ASL group vs. 14.9% in the CTP group, p = 0.005) and symptomatic intracranial hemorrhage (sICH) at 24 h (23.8% in the ASL group vs. 9.9% in the CTP group, p = 0.008) in the CTP group were lower than the ASL group. The ischemic core volume was a common predictor of favorable outcomes in both ASL (p < 0.001) and CTP (p < 0.001) groups.

Conclusion

There were no significant differences in time efficiency and efficacy outcomes between the two groups of patients receiving one-stop ASL and CTP. The proportion of sICH at 24 h and EVT complications of patients in the CTP group was lower than the ASL group. The ischemic core volume was an independent predictor for favorable outcomes.

Investigating Neurologic Improvement After IV Thrombolysis: The Effect of Time From Stroke Onset vs Imaging-Based Tissue Clock

BACKGROUND AND OBJECTIVES

Time from stroke onset is associated with clinical response to intravenous thrombolysis (IVT) with alteplase and is therefore used to select patients for treatment. Alternatively, neuroimaging may be used for treatment in the uncertain or extended time window. We hypothesized that the patient-specific imaging indicator of ischemic lesion progression ("tissue clock") using CT perfusion (CTP) or quantitative net water uptake (NWU) is a predictor of early neurologic improvement (ENI) independent of time.

METHODS

Observational study of anterior circulation ischemic stroke patients with proximal vessel occlusion and known time from symptom onset triaged by multimodal CT undergoing endovascular treatment. Quantitative NWU using an established threshold (11.5%) or CTP lesion core mismatch (EXTEND criteria) was used to estimate ischemic lesion progression. The treatment effect of IVT depending on lesion progression defined by tissue clock vs time clock was assessed by inverse probability weighting (IPW). End points were binarized ENI and functional independence at day 90.

RESULTS

Four hundred nine patients were included, of which 223 (54.5%) received IVT. The proportion of patients within an early time window (<4.5 hours), low NWU, and CTP mismatch were 45.0%, 86.5%, and 80.3%. In IPW, IVT was associated with higher rates of ENI (%-difference: 7.3%, p = 0.02). For patients with CTP mismatch or low NWU, IVT was associated with a 9.6% or 7.2% higher rate of ENI, which was different than the effect of IVT in patients without CTP mismatch or high NWU (-9.3%/-7.3%; p = 0.004/p = 0.03), whereas early treatment window did not modify the effect of IVT.

DISCUSSION

CT-based measures of the "tissue clock" might identify patients who benefit from IVT more accurately than conventional time windows. Considering the high number of patients with early "tissue clock" (low NWU/CTP mismatch) within an extended time window, considerable benefit from IVT using imaging indicators of the "tissue clock" may be achieved.

Reducing Door-In to Door-Out Time for Patients Receiving a Mechanical Thrombectomy Using AutoLaunch Protocol

Background

Door-in to door-out (DIDO) time for large vessel occlusion (LVO) stroke is an emerging stroke performance measure. Initial presentation at a non-Comprehensive Stroke Center (CSC) requires a transfer process that minimizes delays. Our objective was to assess whether DIDO time for stroke patients was reduced after implementation of an AutoLaunch protocol for interfacility transfers.

Methods

This was a pre-post analysis of an AutoLaunch protocol for all acute stroke patients transferred to a CSC for mechanical thrombectomy. The distribution of DIDO times between patients transferred via the AutoLaunch and traditional dispatch protocols were compared.

Results

We evaluated 92 interfacility transfers, with 22 utilizing the AutoLaunch protocol and 70 utilizing traditional dispatch. Among AutoLaunch transfers, the median DIDO time was 85 minutes (IQR: 71, 133), while the median DIDO time among the traditional transfers was 109 minutes (IQR, 84, 144) (p=0.044).

Conclusion

Implementation of an AutoLaunch protocol for patients with suspected LVO was associated with a reduction in DIDO time to CSCs. Further studies should evaluate patient outcomes based on transfer strategies.

Risk factors for lower extremity deep vein thrombosis in acute stroke patients following endovascular thrombectomy: a retrospective cohort study

Background

Deep vein thrombosis (DVT) in lower extremities as a common complication of acute ischemic stroke (AIS) has long been studied. However, as the therapeutic options for AIS continue to advance, the pathogenic mechanisms behind DVT may change. Endovascular thrombectomy (EVT) has replaced intravenous thrombolysis and become the preferred treatment for AIS patients with large vessel occlusions. Therefore, it is important to update our understanding of DVT and its management. This study aimed to determine the prevalence and risk factors of DVT in AIS patients following EVT.

Methods

In this retrospective study, 245 AIS patients who had received EVT were recruited between January 2020 and December 2021. Within 10 days (median 4 days) of thrombectomy, DVT was diagnosed by ultrasonography. Demographic characteristics, clinical findings, and therapeutic procedures were compared between patients with and without DVT using univariate analysis. Cutoff points were defined for EVT time and plasma D-dimer concentration. Multivariable logistic regression was then used to determine the independent risk factors for DVT and evaluate their predictive power.

Results

The prevalence of DVT in AIS patients after EVT was 27.3%. Multifactorial logistic regression analysis showed that age (OR 1.036, 95% CI 1.001-1.073; P = 0.045), female sex (OR 3.015, 95% CI 1.446-6.289; P = 0.003), lower limb muscle strength less than grade three (OR 7.015, 95% CI 1.887-26.080; P = 0.004), longer EVT time (OR 1.012, 95% CI 1.004-1.020; P = 0.003), and higher D-dimer levels (OR 1.350, 95% CI 1.150-1.585; P < 0.001) were independently associated with higher DVT risk in AIS patients following EVT. The cutoff points for operative time of EVT and plasma D-dimer were 65.5 min and 1.62 mg/L, respectively, above which the risk for DVT was dramatically increased with OR > 4 in AIS patients.

Conclusion

AIS patients are at increased risk of developing DVT following EVT particularly if they have undergone prolonged thrombectomy procedures and exhibit high plasma levels of D-dimers. However, the results of our study need to be validated by a multicenter prospective study with a larger population of stroke patients.

Deep Learning-based Assessment of Internal Carotid Artery Anatomy to Predict Difficult Intracranial Access in Endovascular Recanalization of Acute Ischemic Stroke

BACKGROUND

Endovascular thrombectomy (EVT) duration is an important predictor for neurological outcome. Recently it was shown that an angle of ≤ 90° of the internal carotid artery (ICA) is predictive for longer EVT duration. As manual angle measurement is not trivial and time-consuming, deep learning (DL) could help identifying difficult EVT cases in advance.

METHODS

We included 379 CT angiographies (CTA) of patients who underwent EVT between January 2016 and December 2020. Manual segmentation of 121 CTAs was performed for the aortic arch, common carotid artery (CCA) and ICA. These were used to train a nnUNet. The remaining 258 CTAs were segmented using the trained nnUNet with manual verification afterwards. Angles of left and right ICAs were measured resulting in two classes: acute angle ≤ 90° and > 90°. The segmentations together with angle measurements were used to train a convolutional neural network (CNN) determining the ICA angle. The performance was evaluated using Dice scores. The classification was evaluated using AUC and accuracy. Associations of ICA angle and procedural times was explored using median and Whitney‑U test.

RESULTS

Median EVT duration for cases with ICA angle > 90° was 48 min and with ≤ 90° was 64 min (p = 0.001). Segmentation evaluation showed Dice scores of 0.94 for the aorta and 0.86 for CCA/ICA, respectively. Evaluation of ICA angle determination resulted in an AUC of 0.92 and accuracy of 0.85.

CONCLUSION

The association between ICA angle and EVT duration could be verified and a DL-based method for semi-automatic assessment with the potential for full automation was developed. More anatomical features of interest could be examined in a similar fashion.

Predictors and outcome of malignant cerebral edema after successful reperfusion in anterior circulation stroke

BACKGROUND AND OBJECTIVE

Risk factors and predictors of malignant cerebral edema (MCE) after successful endovascular thrombectomy (EVT) were not fully explored. This study aimed to evaluate the incidence and risk factors of MCE after successful reperfusion.

METHODS

We retrospectively analyzed consecutive ischemic stroke patients who underwent EVT in our institution from November 2015 to April 2022. Patients who failed to achieve successful reperfusion (modified thrombolysis in cerebral infarction [mTICI]<2b) were excluded. Based on multivariate logistic models, the best-fit monogram was established. The discriminative performance was assessed by the receiver operating characteristics curve (ROC).

RESULTS

A total of 307 patients were included and 48 (15.6%) were diagnosed with MCE after successful reperfusion. Patients with MCE after successful reperfusion had a lower 3-month favorable outcome (15.2% versus 59.6%; p<0.001), a lower 3-month good outcome (17.4% versus 68.4%; p<0.001), and a higher rate of mortality at 3-month (54.3% versus 8.8%; p<0.001) compared with patients without MCE. Predictors of MCE after successful reperfusion included admission glucose level, baseline National Institutes of Health Stroke Scale (NIHSS) score, stroke etiology, occlusion site and puncture-to-reperfusion (PTR) time>120 min. The area under the curve (AUC) of the nomogram was 0.805 (95% CI, 0.756-0.847).

CONCLUSIONS

MCE after successful reperfusion is associated with poor outcome and mortality. A nomogram containing admission glucose level, baseline NIHSS score, stroke etiology, occlusion site and PTR time>120 min may predict the risk of MCE after successful reperfusion in patients with acute ischemic stroke and treated successfully with EVT.