Abstract WP177: Hemorrhagic Transformation in the Thrombectomy Era: Clinical Predictors, Subtypes and Symptomatic Outcomes

Abstract

Background: Hemorrhagic transformation (HT) is the principal adverse event of thrombectomy. Definitions of symptomatic HT developed during the intravenous thrombolysis (IVT) era are outdated in the endovascular thrombectomy (EVT) era but continue to be widely used. Symptomatic intracerebral hemorrhage (sICH) underestimation may result due to failure to categorize: 1) as sICH-causing hemorrhage types common with EVT but not IVT, such as SAH, IVH; and 2) as sICH-qualifying clinical deterioration patterns common with EVT but not IVT, such as moderate worsening after dramatic initial improvement. Methods: Retrospective, blinded, core lab (2 independent imaging readers), single-center analysis of 149 consecutive thrombectomy patients. Clinical characteristics, technical considerations associated with thrombectomy, severity and subtypes of HT (Heidelberg) and clinical outcomes were analyzed. Results: HT was adjudicated present in 70 out of 149 (47.0%) consecutive thrombectomy patients. Radiologic subtypes were: hemorrhagic infarction (HI-1) (51.4%), HI-2 (25.7%), parenchymal hematoma (PH-1) (4.3%), PH-2 (4.3%), subarachnoid hemorrhage (SAH) (34.3%), intraventricular hemorrhage (IVH) (12.8%), and subdural hemorrhage (SDH) (0%). Coexisting subtypes were present in 27.1 % of HT cases. A total of 8 patients had sICH (5.4% of all patients and 11.4% of patients with HT), conservatively defined by a decline in NIHSS of at least 4 points from baseline to 24 hours post thrombectomy. Only 25% of sICH patients were classified as PH-2, while 62.5% had SAH and 12.5% PH-1. Conclusion: Assessment of HT in EVT requires adoption of later-generation, thrombectomy appropriate classification systems. Multiple, co-existing, radiologic subtypes were present in 1 in 4 EVT patients, making single anatomic categorizations infeasible. Symptomatic hemorrhages were due to subarachnoid hemorrhage in more than half and PH-2 in only one-quarter of symptomatic hemorrhages in this EVT series.