Tmax >4 s volume predicts stroke recurrence in symptomatic intracranial atherosclerotic stenosis with optimal medical treatment.

Background: The time to maximum (Tmax) profile based on computed tomography perfusion (CTP) provides a quantitative assessment of cerebral hemodynamic compromise. We aimed to delineate the Tmax profile in stroke patients with symptomatic intracranial atherosclerotic stenosis (ICAS) and to investigate its predictive role in stroke recurrence after optimal medical treatment.

Methods: Consecutive patients with ischemic stroke within 30 days attributed to 50%-99% ICAS were prospectively enrolled. Baseline tissue volume at different perfusion parameter thresholds based on CTP was automatically calculated using the Rapid Processing of Perfusion and Diffusion (RAPID) software. All patients received optimal medical treatment. The primary outcome was a composite of stroke in the territory of qualifying artery or vascular death within 1 year.

Results: Among 204 patients with symptomatic ICAS, the median volume of Tmax >4 s, Tmax >6 s, and relative cerebral blood flow (rCBF) <30% were 61 mL, 0 mL, and 0 mL, respectively. The 1 year rate of primary outcome was 16.2% (33/204). Tmax >4 s volume was significantly associated with the primary outcome (per 10 mL increase, adjusted hazard ratio (HR), 1.028 (1.008-1.049), P=0.005). The optimal cut-off value of Tmax >4 s volume for predicting the primary outcome was 83 mL. Patients with Tmax >4 s volume >83 mL had a higher risk of the 1 year primary outcome than those with Tmax >4 s volume ≤83 mL (adjusted HR, 7.346 (3.012-17.871), P<0.001), after adjusting for degree of stenosis and stroke mechanisms.

Conclusion: Tmax >4 s volume is a promising perfusion parameter to define hemodynamic compromise in patients with symptomatic ICAS. Patients with a larger volume of Tmax >4 s are likely to have a higher risk of stroke recurrence despite optimal medical treatment.