Influence of Patient Age and Implantation Technique on the Probability of Re-Replacement of the Homograft Aortic Valve
Shu K. Ng PhD, Mark F. O’Brien FRACS, Susan Harrocks BN, Geoffrey J. McLachlan DSc

A study is reported of valve re-replacement (reoperation) in a series of 898 patients undergoing aortic valve replacement (primary and subsequent valve replacements) with cryopreserved homograft valves between 1975 and 1998. The valves were implanted by subcoronary insertion, inclusion cylinder, and aortic root replacement. Probability of reoperation was estimated by adopting a mixture model framework within which estimates were adjusted for two risk factors: patient age at initial replacement, and implantation technique. Younger patient age and root versus non-root replacement were found to be risk factors for reoperation. Valve durability is much less in younger patients, and root replacement patients appear more likely to live longer and thus have a greater chance of requiring reoperation.