Abstract
IntroductionPoor postoperative outcomes have been reported after surgery for infective endocarditis (IE). Whether the absence of positive cultures impacts the prognosis remains a matter of discussion. The aim of this study was to evaluate the impact of negative cultures on the prognosis of surgically treated IE.MethodsThis was a single-center, retrospective study. From January 2000 to June 2019, all patients who underwent valvular surgery for IE were included in the study. The primary endpoint was early postoperative mortality. A covariate balancing propensity score was developed to minimize the differences between the culture-positive IE (CPIE) and culture-negative IE (CNIE) cohorts. Using the estimated propensity scores as weights, an inverse probability treatment weighting (IPTW) model was built to generate a weighted cohort. Then, to adjust for confounding related to CPIE and CNIE, a doubly robust method that combines regression model with IPTW by propensity score was adopted to estimate the causal effect of the exposure on the outcome.ResultsDuring the study period, 327 consecutive patients underwent valvular repair/replacement with the use of cardiopulmonary bypass and cardioplegic cardiac arrest for IE. Their mean age was 61.4 ± 15.4 years, and 246 were males (75.2%). Native valve IE and prosthetic valve IE accounted for 87.5% and 12.5% of cases, respectively. Aortic (182/327, 55.7%) and mitral valves (166/327, 50.8%) were mostly involved; 20.5% of isolated mitral valve diseases were repaired (22/107 patients). The tricuspid valve was involved in 10 patients (3.3%), and the pulmonary valve in 1 patient (<1%). Fifty-nine patients had multiple-valve disease (18.0%). Blood cultures were negative in 136/327 (41.6 %). A higher postoperative mortality was registered in CNIE than in CPIE patients (19% vs 9%, respectively, p = 0.01). The doubly robust analysis after IPTW by propensity score showed CNIE to be associated with early postoperative mortality (odds ratio 2.10; 95% CI, 1.04–4.26, p = 0.04).ConclusionsIn our cohort, CNIE was associated with a higher early postoperative mortality in surgically treated IE patients after dedicated adjustment for confounding. In this perspective, any effort to improve preoperative microbiological diagnosis, thus allowing targeted therapeutic initiatives, might lead to overall better postoperative outcomes in surgically treated IE.
Highlights
Poor postoperative outcomes have been reported after surgery for infective endocarditis (IE) [1]
The tricuspid valve was involved in 10 patients (3.3%), and the pulmonary valve in 1 patient (
Negative cultures in case of IE are mostly caused by sterilization of blood cultures due to prior antibacterial treatment, fastidious microorganisms such as HACEK bacteria or nutritionally variant streptococci, which may require prolonged culture incubation for identification, or intracellular bacteria that cannot be routinely cultured in blood
Summary
Poor postoperative outcomes have been reported after surgery for infective endocarditis (IE) [1]. This work is licensed under the Creative Commons Attribution 4.0. Antibiotic therapy combined with an aggressive surgical debridement of infected tissue whenever indicated. Failure to culture the causative agent (e.g., because of antimicrobial treatment prior to blood culture and/or infection with hardly detectable pathogens) has been associated with increased mortality in IE patients, both in medically and in surgically treated patients, only a few analyses that clearly separate medical and surgical cohorts have been conducted [2,3,4,5]. We assessed the impact of negative blood cultures on the outcome of surgically treated IE patients over a 20-year period
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