Lack of durability of the Mitroflow valve does not affect survival

The aim of the study was to compare the durability and risk of reoperation in patients undergoing isolated aortic valve replacement with either a porcine standard Carpentier Edwards or a Mitroflow pericardial valve.

Follow up evaluation was performed in 118 patients receiving a Mitroflow valve (M) and 94 patients receiving a standard Carpentier Edwards porcine valve (CE) between 1980 and 1987. The two groups were identical in terms of clinical characteristics; only prosthesis size differed, with small-sized valves used more frequently among the Mitroflow group.

The risk of structural valve deterioration (SVD) was 2.3% per patient-year (pt-yr) in CE valves, and 5.4 per pt-yr in M valves. Freedom from SVD was 100%, 87 +/- 4% and 63 +/- 8% at 5, 10 and 15 years for CE valves, and 96 +/- 2%, 56 +/- 7% and 5 +/- 4% for M valves. Freedom of reoperation was 98 +/- 1%, 83 +/- 5% and 76 +/- 7% at 5, 10 and 15 years respectively for CE valves, and 94 +/- 2%, 55 +/- 7% and 11 +/- 9% for M valves. Despite the high number of valve-related reoperations, survival at 5, 10 and 15 years was not affected in M valve patients. Multivariate analysis (Cox model) showed that age and valve type were the two main risk factors for SVD and reoperation, though the latter factor had no impact on survival.

In younger patients (aged < 75 years), the CE valves offer superior results to the M counterpart in valve replacement. However, in patients aged > 75 years, pericardial and porcine bioprostheses demonstrate equivalent durability, despite post-implantation tissue changes in the former material.