BackgroundWe retrospectively evaluated the composition of retrieved clots from ischemic stroke patients to study the association between histological composition and stroke etiologyMethodsConsecutive patients enrolled in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) were included in this study. All patients underwent mechanical thrombectomy and retrieved clots were sent to a central core lab for processing. Histological analysis was performed using martius scarlet blue (MSB) staining, and quantification for red blood cells (RBCs), white blood cells (WBCs), fibrin and platelets was performed using Orbit Image Software. A Wilcoxon test was used for continuous variables and χ2 test for categorical variables.Results1350 patients were included in this study. The overall rate of Thrombolysis In Cerebral Infarction (TICI) 2c/3 was 68%. 501 patients received tissue plasminogen activator (tPA) (37%). 267 patients (20%) had a large artery atherosclerosis (LAA) source, 662 (49%) a cardioembolic (CE) source, 301 (22%) were cryptogenic, and the remainder had other identifiable sources including hypercoagulable state or dissection. LAA thrombi had a higher mean RBC density (46±23% vs 42±22%, p=0.01) and a lower platelet density (24±18% vs 27±18%, p=0.03) than CE thrombi. Clots from dissection patients had the highest mean RBC density (50±24%) while clots from patients with a hypercoagulable state had the lowest mean RBC density (26±21%).ConclusionsOur study found statistically significant but clinically insignificant differences between clots of CE and LAA etiologies. Future studies should emphasize molecular, proteomic and immunohistochemical characteristics to determine links between clot composition and etiology.

Background Computed tomography perfusion (CTP) has been increasingly used for patient selection in mechanical thrombectomy for stroke. However, previous studies suggested that CTP might overestimate the infarct size. The term ghost infarct core (GIC) has been used to describe an overestimation of the final infarct volumes by pre-treatment CTP of >10 ml. Aim We sought to study the frequency and predictors of GIC. Methods A prospectively collected mechanical thrombectomy database at a comprehensive stroke center between September 2010 and August 2020 was reviewed. Patients were included if they had a successful reperfusion (mTICI2b-3), a pre-procedure CTP, and final infarct volume measured on follow-up magnetic resonance imaging. Uni- and multivariable analyses were performed to identify predictors of GIC. Results Among 923 eligible patients (median [IQR] age, 64 [55–75] years; NIHSS, 16 [11–21]; onset to reperfusion time, 436.5 [286–744.5] min), GIC was identified in 77 (8.3%) of the overall patients and in 14% (47/335) of those reperfused within 6 h of symptom onset. The median overestimation volume was 23.2 [16.4–38.3] mL. GIC was associated with higher NIHSS score, larger areas of infarct core and tissue at risk on CTP, unfavorable collateral scores, and shorter times from onset to image acquisition and to reperfusion as compared to non-GIC. Patients with GIC had smaller median final infarct volumes (10.7 vs. 27.1 ml, p < 0.001), higher chances of functional independence (76.2% vs. 55.5%, adjusted odds ratio (aOR) 3.829, 95% CI [1.505–9.737], p = 0.005), lower disability (one-point-mRS improvement, aOR 1.761, 95% CI [1.044–2.981], p = 0.03), and lower mortality (6.3% vs. 15%, aOR 0.119, 95% CI [0.014–0.984], p = 0.048) at 90 days. On multivariable analysis, time from onset to reperfusion ≤6 h (OR 3.184, 95% CI [1.743–5.815], p < 0.001), poor collaterals (OR 2.688, 95% CI [1.466–4.931], p = 0.001), and higher NIHSS score (OR 1.060, 95% CI [1.010–1.113], p = 0.018) were independent predictors of GIC. Conclusion GIC is a relatively common entity, particularly in patients with poor collateral status, higher baseline NIHSS score, and early presentation, and is associated with more favorable outcomes. Patients should not be excluded from reperfusion therapies on the sole basis of CTP findings, especially in the early window.

BackgroundThe first-pass effect (FPE) has emerged as a key metric for efficacy in mechanical thrombectomy (MT). The hyperdense vessel sign (HDVS) on non-contrast head CT (NCCT) indicates a higher clot content of red blood cells.ObjectiveTo assess whether the HDVS could serve as an imaging biomarker for guiding first-line device selection in MT.MethodsA prospective MT database was reviewed for consecutive patients with anterior circulation large vessel occlusion stroke who underwent thrombectomy with stent retriever (SR) or contact aspiration (CA) as first-line therapy between January 2012 and November 2018. Pretreatment NCCT scans were evaluated for the presence of HDVS. The primary outcome was FPE (modified Thrombolysis in Cerebral Infarction score 2c/3). The primary analysis was the interaction between HDVS and thrombectomy modality on FPE. Secondary analyses aimed to evaluate the predictors of FPE.ResultsA total of 779 patients qualified for the analysis. HDVS and FPE were reported in 473 (60.7%) and 286 (36.7%) patients, respectively. The presence of HDVS significantly modified the effect of thrombectomy modality on FPE (p=0.01), with patients with HDVS having a significantly higher rate of FPE with a SR (41.3% vs 22.2%, p=0.001; adjusted OR 2.11 (95% CI 1.20 to 3.70), p=0.009) and non-HDVS patients having a numerically better response to CA (41.4% vs 33.9%, p=0.28; adjusted OR 0.58 (95% CI 0.311 to 1.084), p=0.088). Age (OR 1.01 (95% CI 1.00 to 1.02), p=0.04) and balloon guide catheter (OR 2.08 (95% CI 1.24 to 3.47), p=0.005) were independent predictors of FPE in the overall population.ConclusionOur data suggest that patients with HDVS may have a better response to SRs than CA for the FPE. Larger confirmatory prospective studies are warranted.