Optimal INR level in patients with atrial fibrillation with EHRA type 2 valvular heart disease receiving warfarin

Background To date, there has been no study that compares the efficacy and safety of warfarin in atrial fibrillation (AF) patients with Evaluated Heartvalves, Rheumatic or Artificial (EHRA) type 2 valvular heart disease (VHD). This study was conducted to determine the optimal INR in these patients. Methods This retrospective study enrolled AF patients with EHRA type 2 VHD receiving warfarin in Central Chest Institute of Thailand between January 2016 and December 2018. The incidence density of thromboembolic or bleeding events was calculated. The International normalized ratio (INR) was classified into six groups (less than 1.50, 1.50 to 1.99, 2.00 to 2.49, 2.50 to 2.99, 3.00 to 3.49, and 3.50 or more). The optimal INR level was defined as the lowest incidence density of thromboembolic events and bleeding complications. Results A total of 200 AF patients with EHRA type 2 VHD receiving warfarin were enrolled, contributing to 289 patient‐years of observation period. There were 13 thromboembolic events (4.5 per 100 patient‐years) and 16 bleeding events (5.5 per 100 patient‐years). The incidence density of thromboembolic events was significantly increased in the INR level below 2.00 ( P = .03), while the INR level of 3.50 or more was significantly increased in the incidence density of major bleeding events ( P = .03). Total bleeding and minor bleeding were increased significantly in INR level of 2.50 or more ( P = .04). Conclusions The INR of 2.00 to 2.49 was appeared to be associated with the lowest incidence density of thromboembolic and bleeding events in these patients.