Body mass index and prognosis of infective endocarditis.

Background and objectives: Malnutrition is associated with prognosis in several heart diseases, but there is little information in patients with infective endocarditis (IE). Our objective was to assess the influence of body mass index (BMI) on the prognosis of IE.

Methods: National registry of patients with definite or probable IE from 2008 to 2021, comparing in-hospital and 1-year mortality according to BMI.

Results: From 3645 patients, 91 (2.5%) were underweight, 1432 (39.3%) had normal weight, 1503 (41.2%) were overweight, and 619 (17.0%) had obesity. The median age was lowest in the underweight group (51 vs. >66 years in the other groups, p < 0.001). Patients with underweight/normal weight had an inferior age-adjusted Charlson comorbidity score than those with overweight/obesity (4 vs. 5, p < 0.001). Tricuspid IE was common in patients with underweight (15.4%), while in other groups its prevalence was <6%, p < 0.001. In-hospital and 1-year mortality were respectively: underweight (26.4% and 34.1%), normal weight (19.9% and 25.8%), overweight (22.4% and 27.8%), and obesity (27.8% and 32.5%), both p values ≤0.01. In multivariate analysis, underweight showed a trend for an association with in-hospital mortality (odds ratio 1.67; 95% confidence interval 0.93-3.01 p = 0.09) and a significant association with 1-year mortality (hazard ratio 1.94; 95% confidence interval 1.14-3.31; p = 0.015).

Conclusions: The prognosis of IE in patients with underweight and obesity is worse than in those with normal weight or overweight, and low weight is an independent predictor of 1-year mortality.