Clinical outcomes and anticoagulant intensity in Japanese nonvalvular atrial fibrillation patients ≥ 65 years of age with a CHADS2 score 0-1 and taking warfarin

Abstract

Background: Japanese physicians tend to empirically maintain lower-intensity prothrombin time-international normalized ratios (PT-INR) of 1.6-2.6 for most non-valvular atrial fibrillation (NVAF)patients taking warfarin. However, the optimal anticoagulant intensity in Japanese patients with low CHADS2 (Congestive heart failure, Hypertension, Age ≥ 75, Diabetes, Stroke [doubled])scores is not clear. This study aimed to evaluate the clinical outcome and anticoagulant intensity in Japanese NVAF patients agedB65 years with CHADS2 scores of 0-1 and taking warfarin. Methods: We included 382 consecutive NVAF patients agedB 65 years with CHADS2 scores of 0-1, who took warfarin between 2001 and 2006 (median age, 68 years ; 29.8% women). This study included a median follow-up period of 54 months (1-154 months). The occurrence of thromboembolic events including ischemic stroke, transient ischemic attack and other systemic embolism, as well as major bleeding events were validated through a medical record review. Results: The incidence of thromboembolic and major bleeding events was both 0.9 per 100 patient-year. All thromboembolic events occurred in patients with a PT-INR<2.00. The incidence of major bleeding events increased markedly in patients with a PT-INR B3.00. A HAS-BLED(Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile INR, Elderly and concomitant Drugs/alcohol)scoreB3 was a risk for major bleeding(hazard ratio 4.8, 95% confidence interval 1.6-14.4). A PT-INR of 2.00-2.99 predicted a low incidence of thromboembolic and major bleeding events. Conclusions: Our results showed that a PT-INR of 2.00-2.99 was associated with a low incidence of both thromboembolism and major bleeding in Japanese NVAF patients agedB65 years with CHADS2 score of 0-1 and taking warfarin.