Risk of hemorrhagic transformation with early use of direct oral anticoagulants after acute ischemic stroke: A pooled analysis of prospective studies and randomized trials.

INTRODUCTION: Precise risk of hemorrhagic transformation (HT) in acute ischemic stroke (AIS) remains unknown, leading to delays in anticoagulation initiation for secondary stroke prevention. We sought to assess the rate of HT associated with direct oral anticoagulant (DOAC) initiation within and beyond 48 h post-AIS. METHODS: A pooled analysis of DOAC initiation within 14 days of AIS or transient ischemic attack (TIA) was conducted with six studies (four prospective open label treatment, blinded outcome studies and two randomized trials; NCT02295826 and NCT02283294). The primary endpoint was incident radiographic HT on follow-up imaging (days 7-30). Secondary endpoints included symptomatic HT, new parenchymal hemorrhage, recurrent ischemic events, extracranial hemorrhage, study period mortality, and follow-up modified Rankin Scale score. The results were reported as odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI). RESULTS: We evaluated 509 patients; median infarct volume was 1.5 (0.1-7.8) ml, and median National Institutes of Health Stroke Scale was 2 (0-3). Incident radiographic HT was seen on follow-up scan in 34 (6.8%) patients. DOAC initiation within 48 h from index event was not associated with incident HT (adjusted OR 0.67, [0.30-1.50] P = 0.32). No patients developed symptomatic HT. Conversely, 31 (6.1%) patients developed recurrent ischemic events, 64% of which occurred within 14 days. Initiating a DOAC within 48 h of onset was associated with similar recurrent ischemic event rates compared with those in which treatment was delayed (HR: 0.42, [0.17-1.008] P = 0.052). In contrast to HT, recurrent ischemic events were associated with poor functional outcomes (OR = 6.8, [2.84-16.24], p < 0.001). CONCLUSIONS: In this pooled analysis, initiation of DOAC within 48 h post-stroke was not associated with increased incident risk of HT, and none developed symptomatic HT. The analysis was underpowered to determine the effect of early DOAC use upon recurrent ischemic events.

Dabigatran Treatment of Acute Noncardioembolic Ischemic Stroke.

Background and Purpose- Patients with transient ischemic attack (TIA) and minor ischemic stroke are at risk for early recurrent cerebral ischemia. Anticoagulants are associated with reduced recurrence but also increased hemorrhagic transformation (HT). The safety of the novel oral anticoagulant dabigatran in acute stroke has not been evaluated. Methods- DATAS II (Dabigatran Treatment of Acute Stroke II) was a phase II prospective, randomized open label, blinded end point trial. Patients with noncardioembolic stroke/transient ischemic attack (National Institutes of Health Stroke Scale score, ≤9; infarct volume, ≤25 mL) were randomized to dabigatran or aspirin. Magnetic resonance imaging was performed before randomization and repeated at day 30. Imaging end points were ascertained centrally by readers blinded to treatment. The primary end point was symptomatic HT within 37 days of randomization. Results- A total of 305 patients, mean age 66.59±13.21 years, were randomized to dabigatran or aspirin a mean of 42.00±17.31 hours after symptom onset. The qualifying event was a transient ischemic attack in 21%, and ischemic stroke in 79% of patients. Median National Institutes of Health Stroke Scale (interquartile range) was 1 (0-2), and mean infarct volume 3.2±6.5 mL. No symptomatic HT occurred. Asymptomatic petechial HT developed in 11/142 (7.8%) of dabigatran-assigned patients and 5/142 (3.5%) of aspirin-assigned patients (relative risk, 2.301 [95% CI, 0.778-6.802]). Baseline infarct volume predicted incident HT (odds ratio, 1.07 [95% CI, 1.03-1.12]; P=0.0026). Incident covert infarcts on day 30 imaging occurred in 9/142 (6.3%) of dabigatran-assigned and 14/142 (9.8%) of aspirin-assigned patients (relative risk, 0.62 [95% CI, 0.26, 1.48]). Conclusions- Dabigatran was associated with a risk of HT similar to aspirin in acute minor noncardioembolic ischemic stroke/transient ischemic attack. Registration- URL: https://www.clinicaltrials.gov; Unique identifier: NCT02295826.