Frequency, Severity, Risk Factors, and Outcome of Hemorrhagic Transformation in Anterior and Posterior Stroke.

Background : There are few data on hemorrhagic transformation in posterior circulation strokes (PCS) compared to anterior circulation strokes (ACS). The aim of this study was to retrospectively analyze the incidence of hemorrhagic transformation, its different subtypes, the associations with different risk factors, and the outcome of ACS and PCS patients. Methods : A retrospective analysis of consecutive ischemic stroke patients with hemorrhagic transformation was performed. Clinical and demographic data were collected from electronic patient records. Results : Included were 186 ACS patients and 67 PCS patients. The median age was 77 years, with PCS patients being slightly younger than ACS patients. ACS patients were more likely to be treated with acetylsalicylic acid before stroke. ACS and PCS patients had comparable frequencies and severity of hemorrhagic transformation. After excluding ACS patients who received thrombectomy, PCS patients developed hemorrhagic transformation more frequently compared to ACS patients. Risk factors for hemorrhagic transformation did not differ between ACS and PCS patients and included vitamin K antagonist use before stroke and thrombectomy in ACS patients. There was no correlation between hemorrhagic transformation and stroke outcome. Conclusions : Hemorrhagic transformation occurs with similar frequency in PCS and ACS patients but is more common in PCS patients after the exclusion of ACS patients undergoing thrombectomy.