[Anticoagulation therapy after mechanical prosthetic heart valve replacement with special reference to international normalized ratio (INR)].

We compared the efficacy and complications of anticoagulation with warfarin in 98 patients after isolated mitral valve replacement (MVR 57 pts) and isolated aortic valve replacement (AVR 41 pts). Fifty Medtronic-Hall valves, 33 St. Jude Medical valves, 9 Björg-Shiley valves and 6 other valves were used. In 1991, we made our control standard of prothrombin-time (%) between 25% and 35% (INR 2.3-3.1) and in 1992, between 30% and 40% (INR 2.1-2.8), although INR recommended by ACCP in 1988 was 3 to 4.5. In 1991, mean PT (%) was 31.2% and mean INR was 2.75 in our patients. In 1992, mean PT (%) was 35.0% and mean INR was 2.53. In 1991, we experienced bleeding episodes in three patients and thromboembolism in one case. In 1992, no complication occurred. We conclude that anticoagulant therapy of mean INR 2.53 seemed to be more suitable for Japanese patients than the ACCP standard.