Background & Objectives: Thrombosis with high mortality is a serious complication of prosthetic heart valves and requires treatment, which includes reoperation or using filbrinolytic medications. Regarding the importance of the issue and high mortality rate in reoparation, the present study was performed to determine the efficacy and pragnosis of fibrinolytic therapy on mechanical prosthetic valve.

  Methods: This prospective study was preformed on seventeen patients with PVT who had undergone treatment with streptokinase (SK). After the primary diagnosis, the response to treatment was echocardiography and TEE. Patients with large clots or equal to 1cm clots, pregnant women and patients who had been operated in a month prior to the study were excluded.

  Results: Of the 17 patients (9 female and 8 male, mean age= 43.8 ± 11) 14 had mechanical double-let prostheses (8 mitral & 6 aortic) and 3 patients had single-let prostheses (1 aortic and 2 mitral). 71.3% of the patients with a double-let prosthesis responded completely to the treatment with SK. In none of the patients with a single-let prosthesis the treatment was successful. Also treatment of acute thrombosis was more effective in aortic position (71.4%) than in mitral– valve (50%) (p=0.02). Mortality rate due to cerebral bleeding was 5.8%. Two systemic embolic events (11.8%) occurred (1 cerebral and 1 renal) with transient signs.

  Conclusion: The use of fibrinolytic agents was effective, relatively safe and available especially in patients with less than two weeks’ presentation, small clot and NYHA class I and II and in aortic-position thrombosis.