Isolated replacement of a prosthesis or a bioprosthesis in the mitral valve position.

The operative results of 249 mitral valvular reoperations performed in 215 patients from 1974 through 1986 were reviewed to identify groups at greater risk. Two to 4 reoperations were performed in 28 patients. The mean interval between the first and second valve procedures was 47 +/- 40 months. The most common indications for reoperation were degeneration of bioprostheses (44%) and thrombosis of mechanical prostheses (26%). Thirty patients (12%) died. This rate was significantly higher (p less than 0.02) than that for primary valve procedures performed during the same period. The mortality rate for elective reoperations was 7%. Mortality rates were higher among patients with prosthetic valve endocarditis (6 of 17 cases, 35%), in those undergoing operation on an emergency basis (19 of 82, 23%) and when tricuspid valve replacement or anuloplasty was also performed (9 of 38, 24%) (p less than 0.02). No significant correlation was found between mortality rates and the age or sex of the patients and the types of prosthesis used originally.