Temporal trends in mitral valve surgery in Denmark: changes in patient characteristics and outcomes from 1996 to 2021
Authors: Schops L B , Truong S , Petersen J , Koeber L , Fosboel E L , Oestergaard L K M 
Published: October 2024

Abstract

Background
Mitral valve regurgitation (MR) is associated with increased morbidity and mortality. Mitral valve surgery (MVS) is recommended in severe MR, which is the second most common cause of heart valve surgery in the Western world. Data on national practice patterns are lacking and are essential for the continuous epidemiologic surveillance of the disease.

Purpose
To investigate temporal trends in patient characteristics, incidence and mortality in patients undergoing MVS for MR in Denmark from 1996 to 2021.

Methods
Using Danish nationwide registries, we identified all patients ≥18 years undergoing MVS for MR. Patients operated due to infective endocarditis were excluded. The study population was grouped into one 6-year and four 5-year calendar bands and type of MVS (mitral valve repair, mechanical or biological valve replacement and transcatheter-edge-to-edge repair (TEER)). Temporal trends in patient characteristics were computed. Annual incidence rates were calculated while considering the total Danish population ≥18 years at risk. For one-year postoperative mortality analysis, the reverse Kaplan-Meier estimator and a multivariable Cox proportional hazard analysis were used.

Results
We identified 7,813 patients (median age 67.3 years, 65.6% males) undergoing MVS. Over calendar time, burden of comorbidities decreased while median age increased, Table 1. From 1996 to 2021, a stepwise increase was seen in the overall incidence rate for MVS from 3.87 [95% CI 3.32-4.51] to 7.06 [95% CI 6.34-7.58] per 100,000 person-years (p&lt;0.001). The incidence of mechanical valve replacement statistically significantly decreased (p&lt;0.001), while the incidence of mitral valve repair (p=0.004), biological replacement (p≤0.001) and TEER statistically increased (p=0.015), Figure 1. For the overall study period, one-year mortality was 5.0% for mitral valve repair, 12.7% for mechanical valve replacement, 15.7% for biological valve replacement and 19.0% for TEER. Demographics and one-year mortality stratified by calendar period are shown in Table 1. In the mitral valve repair group, adjusted analysis showed a stepwise statistically significant decrease in one-year mortality with HR 0.30 (95% CI 0.17-0.53, p≤0.001) in 2017-2021 as compared to 1996-2001. In the remaining surgical groups, trends were towards decreasing one-year mortality over calendar periods but did not reach statistical significance.

Conclusion(s)
In this Danish nationwide cohort study, we observed an increase in the incidence of overall mitral valve surgery from 1996 to 2021. The incidence of mechanical valve replacement decreased, while the incidence of mitral valve repair, biological replacement and TEER increased. Mortality rates significantly improved for mitral valve repair patients over calendar time. Continuous epidemiological surveillance of this patient group is required in an era of development in treatment guidelines, surgical methods and patient demographics.Table 1Figure 1