Background and Purpose--Ischemic stroke patients in atrial fibrillation (AF) have a 10% to 20% risk of recurrent stroke. Warfarin reduces this risk by two thirds. However, warfarin is underutilized in this patient group. We performed a prospective study to determine the reasons why warfarin is not started in these patients.

Methods--All patients with AF-associated ischemic stroke over a 12-month period were identified. Demographic and other data, including whether warfarin was commenced or recommended at discharge, and if not why not, were recorded.

Results--Ninety-three of 412 (23%) ischemic stroke patients had paroxysmal or permanent AF. Of these patients, 17 (18%) died, 48 (52%) were discharged home, and 28 (30%) were discharged to institutional care. Only 13 of 64 (20%) patients with known AF were taking warfarin at stroke onset. Warfarin was started (or recommended) in 35 of 76 (46%) survivors. Of those not commenced on warfarin, 32 (78%) were dependent (P<0.001) and 23 (56%) were discharged to institutional care (P<0.001). Warfarin was not started because of severe disability and frailty in 13 (32%), risk of falls in 12 (30%), and limited life expectancy in 4 (10%).

Conclusions--In this cohort of patients with AF, warfarin was primarily underutilized before stroke onset, and it was too late to use anticoagulation, in approximately half, once a stroke had occurred. The decision to start or continue anticoagulation requires clinical judgment and should be made on a case by case basis after a complete risk benefit assessment.