Hypoperfusion Index Ratio as a Surrogate of Collateral Scoring on CT Angiogram in Large Vessel Stroke

Background: This study was to evaluate the correlation of the hypoperfusion intensity ratio (HIR) with the collateral score from multiphase computed tomography angiography (mCTA) among patients with large vessel stroke. Method: From February 2019 to May 2020, we retrospectively reviewed the patients with large vessel strokes (intracranial carotid artery or proximal middle cerebral artery occlusion). HIR was defined as a Tmax > 10 s lesion volume divided by a Tmax > 6 s lesion volume, which was calculated by automatic software (Syngo.via, Siemens). The correlation between the HIR and mCTA score was evaluated by Pearson’s correlation. The cutoff value predicting the mCTA score was evaluated by receiver operating characteristic analysis. Result: Ninety-four patients were enrolled in the final analysis. The patients with good collaterals had a smaller core volume (37.3 ± 24.7 vs. 116.5 ± 70 mL, p < 0.001) and lower HIR (0.51 ± 0.2 vs. 0.73 ± 0.13, p < 0.001) than those with poor collaterals. A higher HIR was correlated with a poorer collateral score by Pearson’s correlation. (r = −0.64, p < 0.001). The receiver operating characteristic (ROC) analysis suggested that the best HIR value for predicting a good collateral score was 0.68 (area under curve: 0.82). Conclusion: HIR is a good surrogate of collateral circulation in patients with acute large artery occlusion.

Ischemic Core Overestimation on Computed Tomography Perfusion

Background and Purpose: Different studies have pointed that CT perfusion (CTP) could overestimate ischemic core in early time window. We aim to evaluate the influence of time and collateral status on ischemic core overestimation. Methods: Retrospective single-center study including patients with anterior circulation large-vessel stroke that achieved reperfusion after endovascular treatment. Ischemic core and collateral status were automatically estimated on baseline CTP using commercially available software. CTP-derived core was considered as tissue with a relative reduction of cerebral blood flow <30%, as compared with contralateral hemisphere. Collateral status was assessed using the hypoperfusion intensity ratio (defined by the proportion of the time to maximum of tissue residue function >6 seconds with time to maximum of tissue residue function >10 seconds). Final infarct volume was measured on 24 to 48 hours noncontrast CT. Ischemic core overestimation was considered when CTP-derived core was larger than final infarct. Results: Four hundred and seven patients were included in the analysis. Median CTP-derived core and final infarct volume were 7 mL (interquartile range, 0–27) and 20 mL (interquartile range, 5–55), respectively. Median hypoperfusion intensity ratio was 0.46 (interquartile range, 0.23–0.59). Eighty-three patients (20%) presented ischemic core overestimation (median overestimation, 12 mL [interquartile range, 41–5]). Multivariable logistic regression analysis adjusted by CTP-derived core and confounding variables showed that poor collateral status (per 0.1 hypoperfusion intensity ratio increase; adjusted odds ratio, 1.41 [95% CI, 1.20–1.65]) and earlier onset to imaging time (per 60 minutes earlier; adjusted odds ratio, 1.14 [CI, 1.04–1.25]) were independently associated with core overestimation. No significant association was found with imaging to reperfusion time (per 30 minutes earlier; adjusted odds ratio, 1.17 [CI, 0.96–1.44]). Poor collateral status influence on core overestimation differed according to onset to imaging time, with a stronger size of effect on early imaging patients( P interaction <0.01). Conclusions: In patients with large-vessel stroke that achieve reperfusion after endovascular therapy, poor collateral status might induce higher rates of ischemic core overestimation on CTP, especially in patients in earlier window time. CTP reflects a hemodynamic state rather than tissue fate; collateral status and onset to imaging time are important factors to consider when estimating core on CTP.

Abstract P102: Elevated Von Willebrand Factor in Patients Presenting With Large-Vessel Occlusion Stroke as First Symptom of COVID-19 Mirrors Levels in Patients With COVID-19 Requiring ICU-Level Care

Introduction: COVID-19 is a coagulopathic disease marked by elevated d-dimers, fibrinogen, and von Willebrand factor (vWF) levels accompanying arterial and venous thrombosis. While the majority of thrombotic events associated with COVID-19 occur in hospitalized patients, a subset of patients with minimal risk factors for CVA but with positive SARS-CoV-2 testing present with stroke as presumed first manifestation of infection. It is unclear if the pro-coagulant milieu present in patients requiring hospitalization for the respiratory complications of COVID-19 is the same as that of patients who present with stroke as first symptom of disease. Methods: Following emergent revascularization, clinical vWF levels were measured in patients presenting with stroke who tested positive for COVID-19. In parallel, plasma vWF levels from 28 patients with COVID-19 requiring ICU-level care and 8 healthy volunteers were measured via ELISA. Results: Three otherwise healthy patients between the ages of 45-55 years with positive test for SARS-CoV-2 presented with large-vessel stroke. By comparison, the average age of non-COVID stroke patients was 66 years. The consistency of the clots extracted through the aspirating catheter was dark, gelatinous throughout, without evidence of calcification, and distal thrombosis was noted minutes after revascularization. The vWF level for one patient was 345%, while the other two patients had vWF levels >400% of normal, exceeding the upper limit of detection of clinical assays. In the ICU cohort, 12 of 28 had thrombotic events during hospitalization. vWF levels were elevated by a mean of 800% over healthy controls with a range of 230-1670%. Conclusions: vWF levels were markedly elevated in both ICU patients and stroke patients with COVID-19 with an overlapping range of elevation over healthy controls. This suggests that widespread endothelial inflammation accompanies infection with SARS-CoV-2 even in the absence of respiratory symptoms.

Abstract P318: Ischemic Core Overestimation on Computed Tomography Perfusion

Introduction: Different studies have pointed that CT perfusion(CTP) could overestimate ischemic core in early time window. We aim to evaluate the influence of time and collateral status on ischemic core overestimation. Methods: Retrospective single-center study including patients with anterior circulation large-vessel stroke that achieved reperfusion after endovascular treatment. Ischemic core and collateral status were automatically estimated on baseline CTP using available software. CTP-derived core was considered as tissue with a relative reduction of cerebral blood flow <30%. Collateral status was assessed using the hypoperfusion intensity ratio(defined by the proportion of the Tmax>6 seconds with Tmax>10 seconds, HIR). Final infarct was measured on 24-48 hours non-contrast CT. Ischemic core overestimation was considered when CTP-derived core was larger than final infarct. Results: Four-hundred and seven patients were included in the analysis. Median CTP-derived core and final infarct were 7mL(IQR 0-27) and 20mL(IQR 5-55), respectively. Median HIR was 0.46(IQR 0.23-0.59). 83 patients(21%) presented ischemic core overestimation(median overestimation, 12mL(IQR 5-41)). Multivariable logistic regression analysis adjusted by CTP-derived core and confounding variables showed that poor collateral status (per 0.1 HIR increase, adjusted odds ratio(aOR) 1.41, 95% confidence interval(CI)1.20-1.65) and earlier onset to imaging time(per 60 minutes earlier, aOR 1.14, CI1.04-1.25) were independently associated with ischemic core overestimation. No significant association was found with imaging to reperfusion time(per 30 minutes earlier, aOR 1.17 CI0.96-1.44). Poor collateral status influence on ischemic core overestimation differed according to onset to imaging time, with a stronger size of effect on early imaging patients(pinteraction<0.01). Conclusion: In patients with large vessel stroke that achieve reperfusion after endovascular therapy, poor collateral status might induce higher rates of ischemic core overestimation on CTP, especially in patients in earlier window time. CTP reflects a hemodynamic state rather than tissue fate; collateral status and onset to imaging time are important factors to estimate ischemic core on CTP.

Abstract P576: Plasma Bacterial Lipopolysaccharide Associates With Carotid Atherosclerosis, a Cause of Large Vessel Stroke

Introduction: Inflammation and infection are associated with cerebrovascular diseases including stroke due to carotid atherosclerotic plaques. C-reactive protein (CRP), an acute-phase protein, is upregulated in the plasma of patients with carotid atherosclerotic plaques. However, little is known about whether bacterial molecules trigger inflammation or play a role in patients with carotid atherosclerotic plaques. Recently, it has been recognized that inflammation associated with atherosclerosis and morbidity and mortality in cardiovascular diseases may be due to lipopolysaccharide (LPS) that is found in the outer wall of all Gram-negative bacteria. These findings prompted this study to explore whether plasma levels of LPS and LPS-binding protein (LBP) are elevated and correlated with CRP levels in patients with asymptomatic carotid plaques (ACP). We also compared LBP levels in patients with ACP to large vessel (LV) strokes due to carotid plaques and to matched controls. Methods: Patients (n = 30) with ACP, LV stroke due to carotid atherosclerosis and age-, sex- matched healthy controls gave consent and had their blood drawn. Plasma was processed for LPS, LBP and CRP detection using separate ELISA for each. Results: Plasma LBP level in ACP (22.7 ± 2.92 μg/ml) was similar to LV stroke (21.6 ± 1.56 μg/ml, p = 0.74, ACP vs LV) but greater than controls (13.6 ± 1.43 μg/ml, p = 0.011, ACP vs controls). In ACP patients, plasma LPS level (159.5 ± 30.5 μg/ml) was greater than controls (42.6 ± 11.7 μg/ml, p = 0.001); plasma CRP levels (20.2 ± 6.2 μg/ml) was higher than controls (5.3 ± 2.1 μg/ml, p = 0.011). There was a positive correlation between LPS levels and LBP levels (r = 0.86, p < 0.00001), LPS levels and CRP levels (r = 0.82, p = 0.00001), and LBP levels and CRP levels (r = 0.89, p < 0.00001) in ACP cases. Conclusions: Plasma LPS, LBP and CRP associate with asymptomatic carotid plaques suggesting a pro-inflammatory state exists in patients with asymptomatic carotid plaques, a cause of large vessel stroke. LPS is postulated to directly upregulate both CRP and LBP. Elevated LBP in large vessel stroke patients suggests a Gram-negative bacteria associated post-stroke inflammatory state.

Association of asymptomatic hemorrhage after endovascular stroke treatment with outcomes

BackgroundIntracerebral hemorrhage (ICH) occurs in ~20%–30% of stroke patients undergoing endovascular therapy (EVT). However, there is conflicting evidence regarding the effect of asymptomatic ICH (aICH) on post-EVT outcomes. We sought to evaluate the effect of aICH on immediate and 90-day post-EVT neurological outcomes.MethodsIn this post-hoc analysis of the multicenter, prospective Blood Pressure after Endovascular Therapy (BEST) study we identified subjects with ICH following EVT. This population was divided into no ICH, aICH, and symptomatic ICH (sICH). Associations with 90-day modified Rankin Scale (mRS) dichotomized by functional independence (0–2 vs 3–6) and early neurological recovery (ENR) were determined using univariate/multivariate logistic regression models.ResultsOf 485 patients enrolled in BEST, 446 had 90-day follow-up data available. 92 (20.6%) developed aICH, and 18 (4%) developed sICH. Compared with those without ICH, aICH was not associated with worse 90-day outcome or lower ENR (OR 0.84 [0.53–1.35], P=0.55, aOR 0.84 [0.48–1.44], P=0.53 for 90-day mRS 0–2; OR 0.77 [0.48–1.23], P=0.34, aOR 0.72 [0.43–1.22] for ENR). aICH was not associated with 90-day outcome or ENR in patients with mTICI ≥2 b (OR 0.78 [0.48–1.26], P=0.33 for 90-day mRS 0–2; OR 0.89 [0.69–1.12], P=0.15 for ENR). A higher proportion of patients with aICH had mTICI ≥2 b than those without ICH (97%vs 87%, P=0.01).ConclusionsaICH was not associated with worse outcomes in patients with large-vessel stroke treated with EVT. aICH was more frequent in patients with successful recanalization. Further validation of our findings in large cohort studies of EVT-treated patients is warranted.

Leptomeningeal Collateral Flow Modifies Endovascular Treatment Efficacy on Large-Vessel Occlusion Strokes

Background and Purpose: We aim to evaluate if good collateral flow (CF) modifies endovascular therapy (EVT) efficacy on large-vessel stroke. To do that, we used final degree of reperfusion and number of device-passes performed, factors previously associated with better functional outcome, as main outcome measures. Methods: Single-center retrospective study including consecutive stroke patients receiving EVT for anterior circulation large-vessel stroke. CF degree was assessed on CT angiography before EVT using a previously validated 4-grade score. Final degree of reperfusion, using modified Thrombolysis in Cerebral Ischemia (mTICI), and number of device-passes performed were prospectively collected. Multivariable analysis was performed to evaluate the influence of collateral flow degree on final degree of reperfusion and number of device-passes performed. Results: Six hundred twenty-six patients were included in the study; 369 patients (59%) presented good collateral flow on CT angiography. Five hundred twenty-two patients (84%) achieved successful reperfusion (mTICI 2B-3) after EVT, 304 (48%) of them with a final mTICI 2C-3. Median number of device-passes was 2 (interquartile range, 1–3). Good CF was independently associated with better final degree of reperfusion (shift analysis for mTICI0-2A/2B/2C-3%, poor CF 19/38/43 versus good CF 15/32/53, adjusted odds ratio, 1.51 [95% CI, 1.08–2.11]). Poor CF was independently associated with higher number of device-passes performed to achieve successful reperfusion (mTICI2B-3; shift analysis for 1/2/3/4+ device-passes, adjusted odds ratio, 1.59, [95% CI, 1.09–2.31]) and complete reperfusion (mTICI2C-3; shift analysis for 1/2/3/4+ device-passes, adjusted odds ratio, 1.70 [95% CI, 1.04–2.90]). Conclusions: Patients with good CF treated with EVT experience higher rates of successful reperfusion with lower number of device-passes. CF may facilitate thrombus retrieval and prevent distal embolization of clot fragments, improving device-passes efficacy.