[Late results of mitral valve replacement with porcine bioprosthesis]

Forty one long-term survivors over 10 years after isolated mitral valve replacement (MVR) were analysed. At first operation, MVR was performed with the porcine bioprosthesis in all 41. However, 28 porcine bioprostheses in 27 patients were replaced with St. Jude Medical (SJM) prosthesis at second or third operation. These 41 survivors were followed from 10 to 13 years (mean 12.0 years). Cumulative duration of follow-up is 490.9 patient-years. Thrombo-embolic accident occurred in 4 patients and the linearized incidence of postoperative systemic thrombo-embolism is 0.8% per patient-year. Twenty nine reoperations were necessary in 27 patients: in 23 because of valve dysfunction due to primary tissue failure, in 2 because of left atrial thrombosis, in 1 because of valve endocarditis, in 1 because of perivalvular leak. Actuarial freedom from valve dysfunction is 35.0% at 13 years. Degeneration of the cusp of the porcine bioprosthesis remains the chief cause of valve failure leading to reoperation and may represent a major problem.