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 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.

BACKGROUND: Transfemoral access is predominantly used for mechanical thrombectomy in patients with stroke with a large vessel occlusion. Following the interventional cardiology guidelines, routine transradial access has been proposed as an alternative, although its safety and efficacy remain controversial. We aim to explore the noninferiority of radial access in terms of final recanalization. METHODS: The study was an investigator-initiated, single-center, evaluator-blinded, noninferiority randomized clinical trial. Patients with stroke undergoing mechanical thrombectomy, with a patent femoral artery and a radial artery diameter ≥2.5 mm, were randomly assigned (1:1) to either transradial (60 patients) or transfemoral access (60 patients). The primary binary outcome was the successful recanalization (expanded Treatment in Cerebral Ischemia score, 2b–3) assigned by blinded evaluators. We established a noninferiority margin of −13.2%, considering an acceptable reduction of 15% in the expected recanalization rates. RESULTS: From September 2021 to July 2023, 120 patients were randomly assigned and 116 (58 transradial access and 58 transfemoral access) with confirmed intracranial occlusion on the initial angiogram were included in the intention-to-treat analysis. Successful recanalization was achieved in 51 (87.9%) patients assigned to transfemoral access and in 56/58 (96.6%) patients assigned to transradial (adjusted 1 side risk difference [RD], −5.0% [95% CI, −6.61% to +13.1%]) showing noninferiority of transradial access. Median time from angiosuite arrival to first pass (femoral, 30 [interquartile range, 25–37] minutes versus radial: 41 [interquartile range, 33–62] minutes; P <0.001) and from angiosuite arrival to recanalization (femoral: 42 (IQR, 28–74) versus radial: 59.5 (IQR, 44–81) minutes; P <0.050) were longer in the transradial access group. Both groups presented 1 severe access complication and there was no difference in the rate of access conversion: transradial 7 (12.1%) versus transfemoral 5 (8.6%) ( P =0.751). CONCLUSIONS: Among patients who underwent mechanical thrombectomy, transradial access was noninferior to transfemoral access in terms of final recanalization. Procedural delays may favor transfemoral access as the default first-line approach. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT05225636.

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.