Peak time of venous outflow: a reproducible CT perfusion marker independently associated with 90-day functional outcome after thrombectomy for anterior-circulation large-vessel occlusion in a retrospective cohort study

Arterial and tissue-level collaterals are established prognostic markers in acute ischemic stroke from large vessel occlusion (AIS-LVO), whereas the value of quantitative venous outflow timing is less certain. We investigated whether CT perfusion-derived peak time of venous outflow (PTV) provides prognostic information complementary to clinical severity, reperfusion status, arterial collaterals, and tissue-level collaterals after endovascular therapy (EVT). This retrospective cohort study included 408 patients with anterior circulation AIS-LVO treated with EVT. PTV was measured on baseline CT perfusion from the superior sagittal sinus time-density curve. Logistic models adjusted for age, atrial fibrillation, diabetes, TOAST, occlusion site, baseline ASPECTS, baseline NIHSS, treatment workflow time (TWT), and eTICI; extended models added modified Tan collateral status and HIR. Favorable outcomes decreased across mean-PTV quartiles (58.8%, 46.1%, 48.0%, 35.3%). Each 1-second PTV increase was associated with lower odds of favorable outcome (adjusted OR 0.946, 95% CI 0.902–0.992; P = 0.022), and Q4 versus Q1 showed lower odds (adjusted OR 0.448, 95% CI 0.208–0.967; P = 0.041). The association persisted after adjustment for arterial and tissue-level collaterals and in an arterially normalized transit-time analysis. Exploratory safety analyses found an association with any intracranial hemorrhage; the unadjusted symptomatic-hemorrhage signal was not retained in the Firth-penalized adjusted sensitivity analysis. In this single-center retrospective cohort, CTP-derived PTV was reproducibly measurable and was associated with favorable functional outcome after EVT. PTV may complement, rather than replace, conventional clinical severity, reperfusion, arterial collateral, and tissue-level collateral assessment; threshold, subgroup, and safety findings are exploratory and require prospective external validation.