Trends in mitral valve surgery in a large multi-surgeon, multi-hospital practice, 1979-1999

Trends in mitral valve operations (MVO) may help to predict the future of mitral valve surgery in the context of changing case mix, population demographics, emerging technology and shifting paradigms.

All adults undergoing single mitral valve operations (MVO) between 1979 and 1999 were reviewed retrospectively according to age, gender and other typical clinical variables, surgical complexity, specific operation and immediate outcome.

A total of 2,055 single MVO was performed. Although coronary artery bypass volumes declined by 15.3% from 1996 to 1999, MVO volumes have continued to increase 58.0% since 1996. For the entire period, there was an insignificant increase in mean age, but an increase in percent male gender and in the prevalence of degenerative and ischemic etiology and mitral regurgitation (MR) pathophysiology. During the 1990s, trends in surgical complexity included a stable 40% prevalence of combined MVO and a stable 9:1 distribution of first operations to reoperations. Technology adoption included a decreased prevalence of mechanical valve usage at the expense of an increased prevalence of mitral valve repair (MVRpr). The prevalence of MVRpr among individual surgeons appeared to be related to a threshold case load of 20 mitral valve operations per year. Predictors of hospital mortality rates for MVO included age > or = 65 years, reoperations and combined MVO. Age > or = 65 years was a predictor of hospital mortality for each category of overall, isolated and combined MVO, mitral valve replacement (MVR) and MVRpr except for combined MVR. Hospital mortality rates for overall MVO, first-op MVO and combined MVO decreased during the 1990s. Hospital mortality comparisons between MVR and MVRpr favored MVRpr, either significantly or by insignificant trend, in every category of overall, isolated and combined groups and when evaluated by age > or = or < 65 year, in overall, isolated and combined groups.

MVO volumes are steadily increasing apparently as a result of the increase in octogenarians and the beginning of the 'baby boomer' wave. Degenerative and ischemic etiologies with MR pathophysiology are on the rise, while rheumatic and endocarditis etiologies are static. The prevalence of MVR with mechanical prostheses has decreased in favor of MVRpr. The prevalence of MVRpr among individual surgeons appears to be related to an annual threshold volume of overall MVO. Hospital mortality risk is related to age and surgical complexity, but is modest and has continued to trend down during the past decade. Hospital mortality appears to favor MVRpr over MVR in all categorical comparisons, either significantly or by insignificant trend. These opposite trend lines for MVR and MVRpr likely represent a paradigm shift away from mechanical solutions in favor of tissue solutions for mitral valve disease, especially for MVRpr.