Risk factors of primary tissue failure within the 11th postoperative year in 217 patients with porcine bioprostheses.

From January 1979 to December 1979, 217 patients underwent valve replacement with porcine bioprostheses. The aim of this study has been to analyze possible host-related risk factors of primary tissue failure (PTF). Of the 207 survivors, 33 have been reoperated on because of prosthetic PTF. Actuarial freedom from PTF was 67.4% +/- 6.04% at 11 years. Several clinical and prosthetic variables have been analyzed as risk factors of PTF by stratification of the event-free actuarial rates with the tests of Mantel and Breslow, and then by introducing the significant variables into the Cox proportional hazards regression model. No significance was found for serum calcium and phosphorus levels, the calcium phosphorus product, normal sinus rhythm, and anticoagulant therapy. Age less than 40 years (40.3 +/- 15.9 vs 74.2 +/- 5.7; p = 0.0348 and p = 0.03) and mitral position (57.7 +/- 7.7 vs 90.9 +/- 5.2; p = 0.0124 and p = 0.0095) were significant predictors of PTF within the 11th postoperative year. Female gender approached statistical significance (63.7 +/- 7.9 vs 72.2 +/- 9.3; p = 0.2001 and p = 0.2043). Cox multivariate analysis showed that age less than 40 years (p = 0.008) and mitral position (p = 0.015) were independent determinants of PTF. In conclusion, we have not been able to confirm the influence of metabolic host factors on the occurrence of PTF, but young age (and not only pediatric age) and mitral position are significant predisposing factors.