Time-varying relationship between ischemic core volume and outcomes after mechanical thrombectomy

Background and purpose

The time-varying relationship between ischemic core volume and neurological outcomes remains uncertain. This study aimed to evaluate how this relationship changes over time in patients undergoing mechanical thrombectomy (MT) and create visual probability heat maps to help clinical decision-making.

Methods

We reviewed data from 168 patients who underwent successful MT (mTICI 2b-3) between March 2021 and December 2023. Patients underwent preoperative computed tomography perfusion (CTP) evaluation using RAPID software, with ischemic core defined as relative cerebral blood flow < 30 % of contralateral blood flow. We used logistic regression models with interaction terms between time from onset to CTP (OTCTP) and ischemic core volume, adjusting for age, sex, time from CTP to reperfusion, and premorbid mRS score. Outcomes were assessed using 90-day mRS scores.

Results

The median patient age was 78.0 years, with 50.5 % male. The median ischemic core volume was 9 mL, and the median OTCTP was 126 min. Poor outcomes, defined as mRS 5–6 were observed in 23.8 % of patients. The probability of poor outcomes increased with longer OTCTP intervals, even with identical ischemic core volumes. An ischemic core volume of 50 mL was associated with probabilities of poor outcomes of 0.18 at 3.0 h, 0.25 at 8.0 h, and 0.56 at 24 h after onset. Compared with final infarct volumes on magnetic resonance imaging, CTP-derived core volumes showed over- and underestimation within 3.0 h, while consistent underestimation was observed beyond 6.0 h.

Conclusions

The clinical significance of CTP-derived ischemic core volume is time dependent and should be considered when selecting patients for treatment. The heat map developed in this study may assist in identifying appropriate candidates for MT.