Abstract
Objective: to investigate how body mass index (BMI) affects the outcome in patients treated surgically for infective endocarditis (IE). Methods: This is a single-center observational analysis of consecutive patients treated surgically for IE. We divided the cohort into six groups, according to the WHO classification of BMI, and performed subsequent outcome analysis. Results: The patient population consisted of 17 (2.6%) underweight, 249 (38.3%) normal weight, 252 (38.8%) overweight, 83 (12.8%) class I obese, 28 (4.3%) class II obese, and 21 (3.8%) class III, or morbidly obese, patients. The median age of the entire cohort was 64.5 [52.5-73.6] years. While only 168 (25.9%) patients were female, women significantly more often exhibited extremes in regards to BMI, including underweight (47.1%) and morbid obesity (52.4%), p = 0.026. Class II and III obese patients displayed more postoperative acute kidney injury (47.9%), p = 0.003, more sternal wound infection (12.9%), p < 0.001, worse 30-day survival (20.4%), p = 0.031, and worse long-term survival, p = 0.026, compared to the results for the other groups. However, the multivariable analysis did not identify obesity as an independent risk factor for 30-day mortality, with an odds ratio of 1.257 [0.613-2.579], p = 0.533. Rather, age > 60, reduced LVEF < 30%, staphylococcal infection, and prosthetic valve endocarditis correlated with mortality. While BMI showed poor discrimination in predicting 30-day mortality on the ROC curve (AUC = 0.609), it showed a fair degree of discrimination in predicting sternal wound infection (AUC = 0.723). Conclusions: Obesity was associated with increased comorbidities, complications, and higher postoperative mortality in IE patients, but it is not an independent mortality risk factor. While BMI is a poor predictor of death, it is a good predictor of sternal wound infections.