Mitral valve reoperation versus first-time surgery for mitral regurgitation: comparison of patient characteristics, type of surgery and mortality in a nationwide cohort
Authors: Truong S , Petersen J , Schmiegelow M D , Due H , Borgersen E H , Schoeps L B , Smerup M , Koeber L , Fosboel E L , Oestergaard L 
Published: October 2024

Abstract

Background
Mitral valve reoperation has been estimated to carry higher surgical risk than first-time mitral surgery. Contemporary data on this area is needed as these associations may lead to under-treatment of recurrent mitral valve disease requiring intervention.

Purpose
To compare patient characteristics, type of surgery, and early mortality related to mitral valve reoperation versus first-time surgery for mitral regurgitation in a nationwide setting.

Methods
We identified patients ≥18 years undergoing first-time surgery for mitral regurgitation 1996-2021 using Danish nationwide registries. Patients undergoing first-time surgery due to endocarditis were excluded. The study population was categorized into 1) patients who underwent first-time surgery only; 2) patients who underwent mitral reoperation. The first group was followed from date of first-time surgery, while second group was followed from date of reoperation, and baseline characteristics were defined according to their respective index dates. Mortality was examined during 180-day follow-up using the reverse Kaplan-Meier estimator and multivariate Cox analysis was used to compare mortality rates within 30 days and 180 days of follow-up. Subgroup analysis was conducted after excluding patients undergoing reoperation for infectious endocarditis (IE).

Results
We identified 7,470 patients; 7,058 (94.5%) underwent first-time surgery only and 412 (5.5%) underwent mitral reoperation. Compared to patients who only underwent first-time surgery, reoperated patients were younger (median age 60 vs. 67) and had fewer comorbidities at time of reoperation, Table 1. Prosthetic replacement was performed in 35.6% of first-time surgeries and 77.2% of reoperations. Mortality after 30 days was 5.2% after first-time surgery and 3.2% after reoperation, while 180-day mortality were 7.8% and 10.6%, respectively, Figure 1. Compared to first-time surgery, reoperation was associated with no significant difference in 30-day mortality (HR=0.68, 95%CI 0.39-1.19), but an increased rate of 180-day mortality (HR=1.60, 95%CI 1.17-2.19, p=0.003). After excluding patients with IE in the reoperation group (n=57), mortality was 2.8% and 8.8% after 30 and 180 days, respectively. In this subgroup, compared to first-time surgery, the 30-day rate of mortality was HR=0.61 (95%CI 0.32-1.14) and after 180 days HR=1.34 (95%CI 0.93-1.93, p=0.11).

Conclusion
Compared to patients who only underwent first-time mitral surgery, patients undergoing mitral reoperation were younger and had fewer comorbidities at time of reoperation. Repair was favoured for first-time surgery, while prosthetic replacement was favoured for reoperations. Compared to first-time surgery, reoperation was associated with an increased risk of 180-day mortality. Though patients undergoing reoperation for mitral valve disease are carefully selected, our findings suggest that this procedure should still be considered at high risk of an adverse outcome.Table 1Figure 1