[Replacement of the mitral and aortic valves with bioprostheses. Long-term results].

The purpose of the study was to analyze the medium-term results (late mortality, thromboembolism, valve failure) in patients who underwent bioprosthetic valve replacement at "A. De Gasperis" Cardiovascular Surgery Division. From October 1975 to December 1982, 195 patients were consecutively operated on and discharged (118 with mitral prosthesis, 54 with aortic prosthesis, 22 with mitral and aortic prosthesis, 1 with mitral and tricuspid prosthesis). We reviewed 115 (97.45%) of 118 patients with mitral prosthesis (mean follow-up 46.61 months) and 54 (100%) patients with aortic prosthesis (mean follow-up 38 months). Eleven late deaths (2.4%/pt-yr) and 13 thromboembolic events (2.8%/pt-yr) occurred in patients with mitral prosthesis, 6 late deaths (3.5%/pt-yr) and 5 thromboembolic events (2.9%/pt-yr) occurred in patients with aortic prosthesis. Actuarial survival curves and actuarial incidence of thromboembolic event-free patients at 5 years are, respectively, 91.2% and 87.3% in patients with mitral prosthesis, 82.8% and 86.3% in patients with aortic prosthesis. The risk factors for thromboembolism were analyzed. Reoperation was requested in 14 cases (10 mitral and 4 aortic prostheses) for prosthetic leak (6 patients) or valve failure (8 patients). In linearized terms, the rate of valve failure requiring reoperation is 1.3%/pt-yr for mitral prostheses and 1.1%/pt-yr for aortic prostheses. The medium-term results suggest that the bioprostheses are, at the present time, an effective choice to the mechanical prostheses, nevertheless they are not free from risks of thromboembolic complications.