Predictors and Prognostic Implications of Hemorrhagic Transformation Following Cerebral Endovascular Thrombectomy in Acute Ischemic Stroke: A Multicenter Analysis

Purpose: Hemorrhagic transformation (HT) following cerebral endovascular thrombectomy (EVT) for large vessel occlusion (LVO) in acute ischemic stroke is associated with poor outcome. Recent studies have shown that EVT can be efficacious in imaging-selected patients as late as 6–24 h from onset (late time window; LTW). We sought to determine predictors and prognostic implications of HT following EVT in LTW. Methods: Consecutive patients undergoing EVT for LVO were recruited into a prospective multicenter database. HT was divided into petechial hemorrhagic-infarction and parenchymal hematoma (PH) type 1 or 2 defined as confluent hemorrhage covering < or > than 1/3 of the infarct volume, respectively. Multivariate analyses were performed to determine variables associated with HT subtypes. Results: Among 611 patients included (mean age 70.5 ± 12.5 years; median NIHSS 16), 115 (18.8%) had HT and 33 of them (5.4%) had PH2. Independent PH2 predictors included failed recanalization (OR 7.0, 95% CI 2.3–21.6), longer time from symptom onset to admission (OR 1.002 per minute 95% CI 1.001–1.003) and hyperlipidemia (OR 3.12; 95%CI 1.12–8.7). HT was not associated with outcome. In contrast, PH2 patients had lower favorable outcome rates (14.3 vs 41.6%, p = 0.004) and higher mortality rates (39 vs 17%, p = 0.001). Patients who underwent EVT in the late versus early window had similar PH2 rates (4.5 vs 6.7%, p = 0.27). In multivariate models, PH2 tripled the odds of both 90-day poor outcome (OR 3.1, 95% CI 1.01–9.5) and 90-day mortality (OR 3.2, 95% CI 1.4–7.3). Conclusions: PH2 following EVT is associated with increased mortality and unfavorable outcome rates. Rates of PH2 are not different between LTW patients and those treated < 6 h from symptom onset.