Secondary stroke prevention in atrial fibrillation: lessons from clinical practice

Secondary prevention trials do not distinguish outcomes according to stroke cause. The purpose of the study was to determine whether trial efficacy of anticoagulation for secondary prevention could be replicated in clinical practice in strokes of different etiology.

A 2-year observation study was undertaken in 288 stroke patients with atrial fibrillation (mean age 76 years; 55% women) who were receiving anticoagulation therapy to maintain an international normalized ratio of 2.0 to 3.0. Comparisons were made of (1) patient characteristics, anticoagulation control, and annual stroke/hemorrhage rates with those of the European Atrial Fibrillation Trial and (2) cause of recurrent stroke by initial stroke subtype.

Subjects were 5 years older (95% CI 3 to 7 years), and more patients had small-vessel stroke (26% versus 14%; 95% CI 3% to 17%) compared with corresponding trial data. The duration spent in the target anticoagulation range (55% versus 59%), recurrent stroke rate (5.1% versus 3.6% per year), and major (2.3% versus 2.2% per year) or minor (9.5% versus 11.8% per year) hemorrhage rates were comparable with those in patients receiving warfarin in the randomized study. Ten of 14 (71%) of embolic recurrences occurred in patients with a previous cardioembolic episode, and 8 of 11 (73%) lacunar recurrences occurred in patients with previous lacunar stroke as the qualifying event for anticoagulation (P:=0.025). Only 3 of 14 cardioembolic compared with 8 of 11 lacunar recurrences occurred during adequate anticoagulation.

Anticoagulation for secondary stroke prevention in clinical practice achieves outcomes comparable with those of randomized trials. Nearly 26% of qualifying strokes and 40% of recurrences were nonembolic; stroke subtype should be considered when making treatment decisions.