Long-term mortality in patients who survive 90 days after surgery for infective endocarditis versus the background population: a nationwide study

Background Valvular surgery for infective endocarditis (IE), can improve survival but carries substantial risk. Limited data exist on long-term outcomes for patients who survive surgery compared to a background population. Purpose To compare long-term mortality and morbidity of IE patients who survive 90-days following valvular surgery to a matched Danish background population using nationwide data. Methods Using Danish registries, we identified patients who survived >90 days post-valvular surgery for first-time IE (2010-2023). Each patient was matched 1:3 with controls from the background population by age, sex, and the following comorbidities: Chronic heart failure, diabetes mellitus, chronic kidney disease, chronic obstructive pulmonary disease, malignancy, and myocardial infarction. All-cause mortality was assessed at 5- and 10-years using Kaplan-Meier estimator and the multivariate Cox model. Further, we examined the time spent in hospital during the first year following the index date. Results We identified 1,050 patients (77.5% male, median age 65.8 years) surgically treated for IE and 3,150 controls (77.5% male, median age 65.8 years). The most common causative microorganisms were: Viridans group streptococci (44.6%), Staphylococcus aureus (23.1%), Enterococci (17.9%). Patients with IE had higher absolute 5-year (20.1% vs 12.9%%, p=0.001) and 10-year (38.5% vs 27.9%, p<0.001) mortality compared to controls. When adjusting for confounders at 5-years and 10 years mortality rates were also higher in IE patients (5-year HR = 1.49 [95% CI 1.24-1.79], and 10-year HR 1.38 [95% CI 1.19-1.60]). IE patients experienced more frequent and longer hospitalizations within the first year post-surgery, as 36.8% IE patients were hospitalized within the first year following index compared to 17.5% in the matched controls. 9.3% of IE patients were hospitalized for >14 days compared to 3.0% in matched controls. 60 IE patients (5.7%) died within the first year following index compared to 61 (1.6%) in the matched controls. Conclusion Patients with IE who underwent valve surgery had a higher crude mortality than their counterparts from the background population. After adjusting for confounders, 5- and 10-year mortality rates remained higher in the IE patient population who survives 90-days following surgery.