OBJECTIVETo investigate whether warfarin is more effective and superior to aspirin for the prevention of thromboembolism in nonvalvular atrial fibrillation in Chinese.

METHODSIn a multicenter randomized trial, the patients diagnosed as nonvalvular atrial fibrillation were randomized to receive aspirin 150 mg - 160 mg once daily or adjusted-dose warfarin (international normalized ratio, 2.0 - 3.0). We compared the effect of the two therapy on the primary end point of ischemic stroke or death from any cause and on the combined end-point (stroke, death, peripheral arteries embolism, TIA, acute myocardial infarction, serious bleeding) during a median follow-up period of 19 months.

RESULTSOf the 704 patients, 420 (59.7%) were male. The average patient age was (63.3 +/- 9.9) years. The median follow-up period is 19 months. The mean dose of warfarin was (3.2 +/- 0.7) mg. Compared with aspirin, the primary end point of death or ischemic stroke was reduced by warfarin (2.7% vs 6.0%, P = 0.03, OR 0.44, 95% CI 0.198 - 0.960) and the relative risk decreased by 56%. The thromboembolism event in the aspirin group was significantly higher than that in warfarin group (10.6% vs 5.4%, P = 0.01, OR 0.48, 95% CI 0.269 - 0.858). There was no significant differences of the mortality rate between the two groups (1.2% vs 2.2%, P > 0.05). The secondary end point was nonsignificantly reduced in warfarin group than that in aspirin group, while the combined end point is statistically decreased by adjusted-dose warfarin (8.4% vs 13.0%, P = 0.047). Warfarin treatment was associated with increased bleeding rate compared to aspirin (6.9% vs 2.4%, P < 0.05), although the major bleeding rate is rather low (1.5%). All the major bleeding events occurred with INR above 3.0.

CONCLUSIONSRandomized control study demonstrated that anticoagulation with adjusted-dosed warfarin (INR 2.0 - 3.0) can significantly reduced the risk of thromboembolism event with slightly increased hemorrhage, compared to aspirin in Chinese population. Under intensive monitoring, warfarin is effective and safe for the moderate to high risk atrial fibrillation patients.