Gradation of Prolonged Venous Transit on Perfusion Imaging Highlights the Association of Deep Venous Drainage Impairment with Unfavorable Functional Outcome in Successfully Reperfused Anterior Circulation Large-Vessel-Occlusion Stroke

BACKGROUND AND PURPOSE: Prolonged venous transit (PVT), derived from perfusion imaging, serves as a surrogate for venous outflow (VO) impairment and has been associated with worse outcomes in acute ischemic stroke due to large-vessel occlusion (AIS-LVO). However, the differential impact of superficial-versus-deep venous drainage impairment on functional outcomes remains unclear. PVT1 and PVT2 were used as surrogates for superficial and deep VO impairment, respectively. MATERIALS AND METHODS: We retrospectively analyzed 128 patients with AIS-LVO from a prospective registry who underwent successful mechanical thrombectomy (modified TICI 2b/2c/3) with available baseline CTP and 90-day mRS scores. PVT– was defined as the absence of time-to-maximum (Tmax) $10 seconds in the posterior superior sagittal sinus (SSS) or torcula (no VO impairment). PVT1 was defined as the presence of Tmax $10 seconds in the posterior SSS only (superficial VO impairment); and PVT2, as the presence of Tmax $10 seconds at the torcula with or without posterior SSS involvement (deep VO impairment). Multivariable logistic regression assessed the association between PVT gradation and the 90-day mRS score. RESULTS: The proportion of patients achieving favorable outcomes (mRS #2) declined stepwise across the PVT gradation: 60.9% in PVT–, 42.1% in PVT1, and 22.7% in PVT2. After we adjusted for age, admission NIHSS score, hypertension, hemorrhagic transformation, IV thrombolysis, and the modified TICI score, PVT gradation remained independently associated with reduced odds of favorable outcome. This association was primarily driven by the PVT2 group, with an adjusted OTR of 0.230 (95% CI, 0.068–0.780) compared with PVT– group. CONCLUSIONS: PVT gradation based on Tmax $10 seconds timing in distinct venous territories provides prognostic insight into the differential contributions of superficial-versus-deep venous drainage dysfunction, supporting the use of PVT as a meaningful VO imaging biomarker. Deep VO impairment, as reflected by PVT2, is the primary driver of worse functional outcomes despite successful reperfusion in AIS-LVO, indicating its stronger negative prognostic impact compared with superficial VO impairment. These findings can help inform prognosis and postacute management strategies.