Factors associated with hemorrhagic transformation after endovascular treatment despite early recanalization

Purpose: To identify new factors associated with hemorrhagic transformation (HT) despite early recanalization in patients with acute ischemic stroke treated with mechanical thrombectomy. Methods: We retrospectively included patients with known onset of large vessel occlusion treated with mechanical thrombectomy +/- intravenous thrombolysis. Non-contrast CT was performed at 24 +/- 12 h from endovascular procedure. We collected data on patient characteristics, risk factors, radiological and treatment features, stroke severity on admission and discharge, carotid intima-media thickness (CIMT), Neutrophils-to-Lymphocytes ratio (NLR), white matter hyperintensities measured according to the Fazekas score on FLAIR MRI data. The main outcome measures were the incidence of HT and factors associated with it. Secondary outcome measures were symptomatic intracerebral hemorrhage and parenchymal hematoma. Results: Of 874 patients, 472 met the inclusion criteria, 211 (44.7%) had HT. Factors significantly associated with increased risk of HT included onset-to-recanalization time, CIMT (normal/mild), ASPECT-MRI < 6, and a higher NLR. We found that beyond 7.67 h from onset-to-recanalization, the risk of HT increases and exceeds 50%. ASPECT-MRI, NLR, and CIMT independently predict HT despite early recanalization. Conclusions: We identified novel factors associated with HT in patients with acute ischemic stroke of known onset treated with mechanical thrombectomy. We found that at 7.67 h from onset to recanalization, the risk of HT is >50%, and we identified factors responsible for HT despite early recanalization.