Prosthetic replacement of the tricuspid valve: biological or mechanical?

Background. Incidence of tricuspid prosthesis replacement was 1.9% of all valvular operations performed between June 6, 1966 and April 18, 1996. Many series report similar figures, but institutional experience is limited and the consensus on treatment modalities is lacking. Methods. One hundred tricuspid operations were performed on 83 patients (46 female). A primary operation was performed in 64 cases, 13 patients had one previous operation, 4 patients had two previous operations, and 2 patients had three previous operations. Seventeen patients required a tricuspid prosthetic valve rereplacement. There were 2 emergent and 17 urgent operations. The New York Heart Association class was IV in 13 patients (mean pulmonary artery pressure, 41 mm Hg), III in 66 patients (mean pressure, 38 mm Hg), and II in 21 patients. The most frequent operation was simultaneous replacement of the mitral and tricuspid valve (41 patients). Seventy biological and 30 mechanical prostheses were used. Total follow-up time was 613 years, mean 7.4 years (median 4.2 years), with a maximum of 27.8 years, and was 92% complete. Results. Operative mortality was 24%. Survival was 0.54 (0.48 to 0.59, n = 39) at 5 years, 0.38 (0.32 to 0.44, n = 27) at 10 years, 0.31 (0.25 to 0.36, n = 19) at 15 years, 0.29 (0.23 to 0.34, n = 11) at 20 years, and 0.17 (0.098 to 0.26, n = 3) at 25 years. Early mortality was increased from higher New York Heart Association class (hazard ratio = 2.2), congenital disease (hazard ratio = 6.9), and valvuloplasty failure (hazard ratio = 4.3). The constant risk phase (4%/patient-year) after 2 years was enhanced by older operative age (hazard ratio = 1.4). Prosthetic type had no independent effect. Biological prostheses were at risk for 300 years and had a reoperation incidence of 4.7%/patient-year (14 events); mechanical prosthesis were at risk for 137 years with a rate of 2.2%/patient-year (3 events) (p = 0.21). Three valve thromboses were observed in old-design mechanical prosthesis. Bioprosthetic degeneration showed a steeper rate after 7 years. Conclusions. This study does not show a clear superiority of biological versus mechanical prostheses. In the long run survival with mechanical prostheses could be superior, given the high rate of bioprosthetic degeneration after 7 years.