OPTIMAS: OPtimal TIMing of Anticoagulation after AF-associated acute ischaemic Stroke: a randomised controlled trial

Every day in the UK, doctors must decide when to restart blood-thinning drugs in patients who have just had a stroke caused by atrial fibrillation—start too soon and risk bleeding into the brain, start too late and risk another stroke. The OPTIMAS trial will randomise 3,474 such patients to receive anticoagulation either within four days of their stroke or after the standard five-to-fourteen-day window, using any direct oral anticoagulant (DOAC). The core question is whether earlier treatment reduces the combined risk of recurrent stroke, brain haemorrhage, systemic embolism, and death at 90 days. Current UK guidelines recommend waiting five to fourteen days, but this is based on limited evidence. If OPTIMAS shows that early DOAC treatment is both safe and effective, it could change clinical practice worldwide—shortening hospital stays, reducing the anxiety of delayed treatment, and preventing thousands of avoidable second strokes each year. If early treatment proves harmful, the trial will confirm the safety of the current cautious approach. Either way, the result will give clinicians a clear, evidence-based answer to a decision they face daily.