Clinical durability of the Hancock porcine bioprosthetic valve.

The principal feature of the Hancock xenograft bioprosthesis which remains to be completely defined is long-term durability. This report provides extended data regarding valve durability derived from a data base of 1,407 patients (707 aortic [AVR] and 700 mitral [MVR] replacements) who received Hancock bioprostheses between 1971 and 1979; cumulative duration of follow-up was 1,732 patient-years for AVR and 1,843 for MVR patients, with a maximum follow-up duration of 8.4 years. One hundred seventy-nine patients were followed for more than 5 years and 67 for more than 6 years. Valve failure was defined on the basis of one or more of the following criteria: (1) postoperative development of a new regurgitant murmur, (2) thrombotic valvular occlusion, (3) infective endocarditis resulting in reoperation or death, and (4) hemodynamic valvular dysfunction confirmed by catheterization and resulting in reoperation or death. Twenty-one such failures occurred among all AVR patients and 23 among all MVR patients. The actuarial probability of freedom from valve failure (all causes) was 95.4% +/- 1.2% (+/- SEM) for adult AVR patients 5 years postoperatively and 90.9% +/- 2.6% for adult MVR patients 6 years postoperatively. The probability of freedom from primary tissue failure in adults was 99% +/- 1% in AVR patients at 5 years and 94.3% +/- 2.4% in MVR patients at 6 years. The linearized incidence of primary tissue failure in children (< 15 years old) was 9.8% per patient-year (combined AVR and MVR patients), compared to 0.2% per patient-year among all adult patients in the analysis. The combined actuarial incidence of primary tissue failure among adults with AVR and MVR was 98.6% +/- 0.7% at 5 years and 94.2% +/- 2.3% at 6 years; thus there appears to be a slight acceleration in the rate of valve tissue failure between 5 and 6 years after operation. The incidence of failure, however, remains acceptably low through 6 years of follow-up, and continued clinical use of the xenograft bioprosthesis seems warranted.