Most stroke physicians will have been asked the best time to start anticoagulation for a patient with atrial fibrillation (AF) and acute ischemic stroke. There is no question that long-term anticoagulation with a direct oral anticoagulant or warfarin sodium reduces the risk of strokes in patients with AF, but the right time to start anticoagulation is uncertain.
The best available evidence comes from participants with AF randomly allocated to receive heparins, aspirin, or placebo in acute ischemic stroke.1,2 In a meta-analysis of these trials, use of heparins led to more cases of intracranial hemorrhage (ICH) (summary odds ratio, 2.89 [95% CI, 1.19-7.01]; no significant heterogeneity) but no clear reduction of recurrent ischemic stroke (summary odds ratio, 0.68 [95% CI, 0.44-1.06]; no significant heterogeneity) or reduced death or disability.3 At 14 days after stroke, the reduction in ischemic stroke (2.6%) was similar to the increase in ICH (2.4%) for participants with AF in the International Stroke Trial who were treated with unfractionated heparin, 12 500 U compared with those who did not receive heparin.4 Therefore, there is no clear indication from randomized trials that early anticoagulation—at least with a heparin—is advantageous in patients with AF who have experienced a stroke. Most clinical guidelines either avoid specific recommendations or recommend waiting up to 2 weeks following a stroke before starting an oral anticoagulant.5,6
Ng KKH, Whiteley W. Anticoagulation Timing for Atrial Fibrillation in Acute Ischemic StrokeTime to Reopen Pandora’s Box?. JAMA Neurol. Published online September 11, 2017. doi:10.1001/jamaneurol.2017.1919