Purpose: To identify optimum international normalized ratio (INR) levels and required warfarin doses and anticoagulation-related complications in patients following mechanical prosthetic valve replacement.
Materials and Methods: Five hundred and seven patients were prospectively followed up for 10 years (2008.5 patient-years). Anticoagulation-related complications were classified into hemorrhage and thromboembolism.
Results: Two hundred and ninety-two (57.6%) were males and 215 (42.4%) were females with a mean age of 29.5 +/- 11.32 years. A total of 268 (52.9%) patients had mitral, 96 (18.9%) had aortic and mitral, and 76 (15%) had aortic valve replacement (AVR). Valves implanted totaled 345 (68%) ball and cage, 126 (24.9%) bileaflet, and 36 (7.1%) single disc. There were 10,669 total visits, with mean INR 2.6 +/- 0.59 and mean warfarin 5.17 +/- 1.6 mg. Sixty-four (3.2% per patient-years) events occurred during follow-up, of which 23 (1.13% per patient-years) events were due to thromboembolism and 41 (2.04% per patient-years) to bleeding. Atrial fibrillation occurred in 12 (52.4%) patients having thromboembolic events and in 24 (58.5%) suffering from bleeding complications. Among thromboembolic events, valve thrombosis occurred in 9 patients (0.44% per patient-years) and cerebrovascular accidents (CVAs) in 14 (0.69% per patient-years). Atrial fibrillation was present in 7 (77.8%) patients in the valve thrombosis group and in 5 (35.7%) in the CVA group. Of 41 bleeding events, 8 (0.39% per patient-years) were minor episodes, 20 (0.99% per patient-years) were major episodes, and severe hemorrhage occurred in 5 (0.34% per patient-years). Intracranial hemorrhage leading to CVA was seen in 8 patients (0.34% per patient-years). There were 22 (1.1% per patient-years) fatal hemorrhages and 15 (0.74% per patient-years) fatal thromboembolic events. In-hospital mortality was 25 (4.9%), and 62 (12.2%) were late deaths; of these, 37 (7.3%) were anticoagulation related.
Conclusions: Anticoagulation for mechanical heart valve replacement can be managed with INR levels of 2-2.5 with acceptable hemorrhagic and thromboembolic events.