Reassessing Effect of Length of Antibiotic Therapy in Post-Surgical Endocarditis (RELAPSE): is extended antibiotic therapy still necessary after surgical intervention?

Infective endocarditis (IE) requiring surgical intervention is a complex condition in which the optimal postoperative antibiotic duration remains uncertain. While current guidelines suggest that antibiotic duration does not need to be extended after cardiac intervention when intraoperative cultures are negative, this recommendation does not account for real-world variability in patient risk factors. As a result, some clinicians extend antibiotic therapy after cardiac intervention, although the impact of this practice in clinical settings is unknown. This was a single-center retrospective cohort study of patients with IE who underwent surgical intervention between January 2013 and November 2017. Patients were grouped based on postoperative antibiotic strategy: those in whom antibiotics were restarted after cardiac surgery (extended group) versus those in whom the preoperative antibiotic course was included toward total treatment duration (original group). The primary outcome was a composite of one-year infection-related mortality and IE relapse after cardiac intervention. 235 patients met study inclusion criteria, 182 in the extended group and 53 in the original group. 91.5% of patients had bacteremia with a median duration of 4 days (IQR 2–7). 187 (79.6%) had intraoperative cultures sent, with 91 (48.7%) being positive. The study revealed no statistically significant difference between the two groups in the primary outcome (win ratio 1.30, favoring the extended group; 95% CI, 0.73–2.30; p-value 0.37) after adjusting for potential confounders. In this study, no statistically significant difference was observed in one-year infection-related mortality or relapse between antibiotic strategies; however, the wide confidence intervals and limited statistical power prevent exclusion of a clinically meaningful difference. Further prospective studies are needed to better define the role and optimal duration of extended postoperative antibiotic therapy.