Altered Platelet Function in Patients with Prosthetic Mitral Valves

Platelet survival time and platelet adhesiveness and aggregation were examined in 16 patients with prosthetic mitral valves. Subsequently, nine patients were treated with sulfinpyrazone in doses of 400 mg and 800 mg/day, and the studies were repeated after a treatment period of 5 to 8 weeks. 51Chromium survival time was shortened in 15 of 16 patients, and the mean value for the entire group was 5.49 + 0.23 days (normal, 6.73 + 0.21 days; P < 0.001). Mean platelet adhesiveness in glass bead columns was 53 + 5% (normal, 30 to 60%). Platelet aggregation (turbidometric technic of Born) was normal. Treatment with 400 mg of sulfinpyrazone daily reduced platelet adhesiveness to 40 5% (P < 0.05), but effected no change in platelet survival time or platelet aggregation. Therapy with 800 mg of sulfinpyrazone daily corrected platelet survival time to normal, 6.68 + 0.57 days (P < 0.01), but it produced no further decrease in adhesiveness and no change in aggregation. It is concluded that platelet abnormalities regularly occur in patients with prosthetic mitral valves and may contribute to thromboembolism in this group. Platelet survival time is a more sensitive measure of altered platelet kinetics than platelet adhesiveness or platelet aggregation. Therapy with 800 mg of sulfinpyrazone per day corrects demonstrated abnormalities and may be useful for prevention of thromboembolism in patients with prosthetic mitral valves.