Mitral valve surgery is associated with substantial perioperative risk and long-term complications. Data on long-term outcomes following surgery remain scarce and are hypothetically modified by age and comorbidities.

This Danish nationwide study included patients ≥60 years of age undergoing mitral valve surgery from 2000-2018. Patients were observed from day of surgery until outcome of interest (ie, rehospitalization or death) or maximum 1 year of follow-up. The absolute risks of outcomes were assessed, and associated factors were evaluated. Based on age and comorbidities, patients were stratified in 4 groups: low (<75 years + 0 comorbidities), low intermediate (≥75 years/1 comorbidity), high intermediate (≥75 years + 1 comorbidity/2 comorbidities), and high risk of death (≥75 years + ≥2 comorbidities).

In total, 4,202 patients (62.9% men) were identified. Within 1 year after surgery, 504 (12.0%) died and 2,456 (58.5%) were rehospitalized. Factors associated with death included older age (>75 years), chronic obstructive lung disease, heart failure, prior myocardial infarction, prior stroke, liver disease, and kidney disease. The 1-year risks of death among patients in low, low-intermediate, high-intermediate, and high risk of death were 3.6%, 10.3%, 19.6%, and 27.7%, respectively. Diabetes mellitus and chronic obstructive lung disease were associated with an increased incidence of rehospitalization, and the incidence of rehospitalization was similar among the 4 abovementioned groups (57.8%-62.8%).

Mortality and rehospitalization risks after mitral valve surgery varied substantially with age and comorbidities. High-risk patients with >25% 1-year mortality may be easily identified using readily available clinical features.

In Denmark, registry-based studies that are conducted for the sole purpose of statistics and scientific research do not require ethical approval or informed consent by law. However, the study is approved by the data responsible institute (the Capital Region of Denmark [approval number: P-2019-348]) in accordance with the general data protection regulation.