The prevalence and risk factors of hemorrhagic transformation (HT) after acute ischemic stroke HT have not been adequately delineated. We performed a systematic review and meta-analysis to identify English-language prospective observational MEDLINE and EMBASE-listed reports of acute ischemic stroke with HT published from 1985–2017. Studies that used the ECASS-2 definitions of hemorrhagic transformation subtypes, hemorrhagic infarction (HI), and parenchymal hematoma (PH) were included. Patients treated with intravenous thrombolysis with tissue plasminogen activator (IV-tPA) were compared with those who did not receive thrombolysis. A total of 65 studies with 17,259 patients met inclusion criteria. Overall, HT prevalence was 27%; 32% in patients receiving IV-tPA vs. 20% in those without. Overall PH prevalence was 9%; 12% in IV-tPA treated patients vs. 5% in those without. HT was associated with a history of atrial fibrillation (OR 2.94) and use of anticoagulants (OR 2.47). HT patients had higher NIHSS (Hedge’s-G 0.96) and larger infarct volume (diffusion-weighted MRI, Hedge’s-G 0.8). In IV-tPA treated patients, PH correlated with antiplatelet (OR 3) and statin treatment (OR 4). HT (OR 3) and PH (OR 8) were associated with a poor outcome at 90-day (mRS 5–6). Hemorrhagic transformation is a frequent complication of acute ischemic stroke and is associated with poor outcome. Recognition of risk factors for HT and PH may reduce their incidence and severity.

Recanalization in cerebral venous thrombosis (CVT) can begin as early as 1 week after initiating therapeutic anticoagulation. The clinical significance of recanalization remains uncertain. We aimed to investigate the association between recanalization and functional outcomes and explored predictors of recanalization. A systematic literature search was conducted (EMBASE, MEDLINE, Cochrane library) to identify: (1) patients with CVT aged ≥18 years treated with anticoagulation only; (2) case series, cohort, or randomized controlled trial studies; and (3) reported recanalization rates and functional outcomes using either a modified Rankin Scale (mRS) or sequelae of CVT at last follow-up. Meta-analysis was performed using pooled odds ratios (ORs) with exploration of sex and age effects using meta-regression. Twenty-three studies were eligible with 1418 individual patients in total. Timing of reimaging and clinical reassessment was variable. Absence of recanalization was associated with increased odds of an unfavorable functional outcome (mRS 2-6 versus 0-1; OR, 3.66; 95% CI, 1.73-7.74; p = 0.001), CVT recurrence (OR, 8.81; 95% CI, 1.63-47.7; p = 0.01), and chronic headache (OR, 2.78; 95% CI, 1.16-6.70; p = 0.02). On meta-regression, the relationship between recanalization and mRS differed by the proportion of female patients, where lower proportions of women were associated with higher likelihood of a worse outcome, but not by mean participant age. There was no incremental benefit of full compared with partial recanalization with respect to favorable mRS or recurrence, but odds of chronic headache were higher with partial versus full recanalization (OR, 3.80; 95% CI, 1.43-10.11; p = 0.008). Epilepsy and visual sequelae were not associated with recanalization. Absence of recanalization was associated with worse functional outcomes, CVT recurrence, and headache, but outcomes were modified by sex. The degree of recanalization was significant in relation to headache outcomes, where partial compared with complete recanalization resulted in a greater likelihood of residual headache. Prospective studies with common timing of repeat clinical-neuroimaging assessments will help to better ascertain the relationship and directionality between the degree of recanalization and outcomes.