Current guidelines advise treating paroxysmal AF in the same way as sustained AF but the evidence is weak, with only one retrospective analysis comparing the risk of stroke in patients with paroxysmal AF vs chronic AF (analysis of the SPAF trials, performed 15 years ago and limited to patients treated with aspirin). The ACTIVE W trial showed that warfarin is more effective than aspirin plus clopidogrel for the prevention of vascular events (stroke, embolism, MI and vascular death) in patients with AF. A recent substudy of this trial looked at the risk of stroke in 1,202 patients with paroxysmal AF compared with 5,495 with sustained AF, and the effectiveness of thromboprophylaxis in these patients. ' This substudy has shown that the risk of stroke is similar, irrespective of whether AF is paroxysmal or sustained, and that anticoagulation therapy is equally effective in both groups. Other factors, such as age and cardiovascular comorbidity, remain central to the ultimate choice of thromboprophylaxis in these patients.'