LOW-DOSE ANTICOAGULANT MANAGEMENT OF PATIENTS WITH ST JUDE MEDICAL MECHANICAL VALVE PROSTHESES

Between February 1984 and December 1990, 622 St. Jude Medical valves were implanted in 548 patients. There were 382 males (69.7 %) and 166 females (30.3 %) with a mean age of 32.3 +/- 11.9 years (range 9-68 years). Sixty-eight percent of the patients were referred from rural areas. Three hundred and forty patients underwent aortic valve replacement (AVR), 134 had mitral valve replacement (MVR), and 74 had aortic and mitral valve replacement (DVR). The hospital mortality was 4.7 % (16/340) for AVR, 6.7 % (9/134) for MVR and 10.8 % (8/74) for DVR. Follow-up period ranged from 1.1 to 7.2 years. Total follow-up was 1317.3 patient-years (py). All patients received 2.5 mg warfarin, 225 mg dipyridamole, and 250 mg aspirin daily, regardless of prothrombin time and cardiac rhythm. Thromboembolism was observed in 10 patients (0.75 py); there were 3 mortalities (0.22 % py). Valve thrombosis occurred in 4 patients (0.30 % py) : 3 in the MVR group (0.94 % py) and 1 in the AVR group (0.11 % py). Hemorrhage occurred in 19 patients (1.44 % py) with 11 fatal outcomes (0.83 % py). It is concluded that a random daily dose of 2.5 mg warfarin with 2 25 mg dipyridamole and 250 mg aspirin is sufficient for safe anticoagulation without the need for serial prothrombin-time adjustments.