Impact of Anticoagulation Intensity in Korean Patients with Atrial Fibrillation: Is It Different from Western Population?

Background and objectives Although anticoagulation with warfarin is recommended as an international normalized ratio (INR) of prothrombin time between 2.0 and 3.0 and mean time in the therapeutic range (TTR) ≥70%, little has been proven that universal criteria might be suitable in Korean atrial fibrillation (AF) patients. Methods We analyzed 710 patients with non-valvular AF who took warfarin. INR value and clinical outcomes were assessed during 2-year follow-up. Intensity of anticoagulation was assessed as mean INR value and TTR according to target INR range. Primary net-clinical outcome was defined as the composite of new-onset stroke and major bleeding. Secondary net-clinical outcome was defined as the composite of new-onset stroke, major bleeding and death. Results Thromboembolism was significantly decreased when mean INR was over 1.6. Major bleeding was significantly decreased when TTR was over 70% and mean INR was less than 2.6. Mean INR 1.6-2.6 significantly reduced thromboembolism (adjusted hazard ratio [HR], 0.40; 95% confidence interval [CI], 0.19-0.85), major bleeding (HR, 0.43; 95% CI, 0.23-0.81), primary (HR, 0.50; 95% CI, 0.29-0.84) and secondary (HR, 0.45; 95% CI, 0.28-0.74) net-clinical outcomes, whereas mean INR 2.0-3.0 did not. Simultaneous satisfaction of mean INR 1.6-2.6 and TTR ≥70% was associated with significant risk reduction of major bleeding, primary and secondary net-clinical outcomes. Conclusions Mean INR 1.6-2.6 was better than mean INR 2.0-3.0 for the prevention of thromboembolism and major bleeding. However, INR 1.6-2.6 and TTR ≥70% had similar clinical outcomes to INR 2.0-3.0 and TTR ≥70% in Korean patients with non-valvular AF.