Incidence and factors associated with mitral valve reoperation in patients undergoing intervention for mitral regurgitation: a nationwide cohort study

Abstract Background When intervention is needed for the treatment of mitral regurgitation, the risk of reoperation is of concern for both patients and physicians. As such, contemporary and nationwide data on the incidence and factors associated with mitral reoperation can provide crucial information to support patient education and clinical follow-up after intervention. Purpose To examine the incidence of mitral reoperation in patients operated for mitral regurgitation. Second, to assess whether reoperation rates differed according to time since surgery and identify potential factors associated with reoperation. Methods Using Danish nationwide registries, patients undergoing first-time surgery for mitral regurgitation 1996–2021 were identified. Exclusion included first-time surgery due to endocarditis. According to index surgery, the population was categorized into 1) mitral repair; 2) mechanical prosthesis; 3) bioprosthesis. Patients were followed from date of discharge. Cumulative incidence of reoperation was examined using competing risk analysis during a maximum of 20-years follow-up. Crude incidence rates of reoperation were reported from 0-6 months and for overall study period. Multivariate Cox analysis was used to examine factors associated with reoperation. Results We identified 7,063 patients: 4,680 (66.3%) with repair (72% male, median age 66), 1,273 (18.0%) with mechanical prosthesis (52% male, median age 59), and 1,110 (15.7%) with bioprosthesis (57% male, median age 74). Median follow-up was 7.2 years, 10.7 years, and 4.5 years, respectively. At end of follow-up, cumulative incidences were 7.7% for repair, 6.8% for mechanical prostheses, and 7.5% for bioprostheses. Of these, reoperation was preceded by endocarditis in 8.0%, 21.5%, and 30.4% of the respective patient groups. The cumulative incidence function demonstrates that the highest proportion of reoperations occurred within first six months, Figure 1. From 0-6 months following surgery, incidence rates per 100 person-years were 9.1 for repair, 11.7 for mechanical prostheses, and 18.4 for bioprostheses, while this was 8.6, 9.4, and 17.0, respectively for the overall study period. Factors associated with increased rate of reoperation were heart failure (HR=1.80, 95% CI 1.40-2.32), chronic renal failure (HR=1.48, 95% CI 1.11-1.98) and chronic obstructive pulmonary disorder (COPD) (HR=1.34, 95% CI 1.01-1.77), Figure 2. Compared to mitral repair, mechanical prostheses were associated with lower rate of reoperation (HR=0.57, 95% CI 0.42-0.78), while there was no statistically significant difference between repair and bioprostheses (HR=1.10, 95% CI 0.81-1.50). Conclusion In patients operated for mitral regurgitation, cumulative incidences of reoperation with a maximum of 20-year follow-up were 7.7% for repair, 6.8% for mechanical prostheses, and 7.5% for bioprostheses. Comorbidities such as heart failure, renal failure and COPD were associated with increased risk of reoperation.Figure 1Figure 2