Background and purpose: It is unknown when to start anticoagulation after acute ischemic stroke (AIS) from atrial fibrillation (AF). Early anticoagulation may prevent recurrent infarctions but may provoke hemorrhagic transformation as AF strokes are typically larger and hemorrhagic transformation-prone. Later anticoagulation may prevent hemorrhagic transformation but increases risk of secondary stroke in this time frame. Our aim was to compare early anticoagulation with apixaban in AF patients with stroke or transient ischemic attack (TIA) versus warfarin administration at later intervals.
Methods: AREST (Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation) was an open-label, randomized controlled trial comparing the safety of early use of apixaban at day 0 to 3 for TIA, day 3 to 5 for small-sized AIS (<1.5 cm), and day 7 to 9 for medium-sized AIS (≥1.5 cm, excluding full cortical territory), to warfarin, in a 1:1 ratio at 1 week post-TIA, or 2 weeks post-AIS.
Results: Although AREST ended prematurely after a national guideline focused update recommended direct oral anticoagulants over warfarin for AF, it revealed that apixaban had statistically similar yet generally numerically lower rates of recurrent strokes/TIA (14.6% versus 19.2%, P=0.78), death (4.9% versus 8.5%, P=0.68), fatal strokes (2.4% versus 8.5%, P=0.37), symptomatic hemorrhages (0% versus 2.1%), and the primary composite outcome of fatal stroke, recurrent ischemic stroke, or TIA (17.1% versus 25.5%, P=0.44). One symptomatic intracerebral hemorrhage occurred on warfarin, none on apixaban. Five asymptomatic hemorrhagic transformation occurred in each arm.
Conclusions: Early initiation of anticoagulation after TIA, small-, or medium-sized AIS from AF does not appear to compromise patient safety. Potential efficacy of early initiation of anticoagulation remains to be determined from larger pivotal trials. Registration: URL: https://www.clinicaltrials.gov/; Unique identifier: NCT02283294.
Keywords: atrial fibrillation; ischemic stroke; safety; secondary prevention; warfarin.