Abstract 14609: Exposure to Any Hospitalization and Specific Invasive Procedures Post Open Heart Valve Surgery Increases the Risk of Endocarditis

Introduction: Infective endocarditis (IE) after cardiac valve surgery is associated with high morbidity and mortality. Nosocomial exposure is a growing cause of IE in general. We investigated the risk of post valve surgery endocarditis (PVE) in patient who had any hospitalization and specific nosocomial exposures after open heart valve surgery. Methods: We identified all ≥18yo patients who had their first open heart cardiac valve surgery between 2001-2017 in New South Wales, Australia from the Admitted Patient Data Collection (APDC) registry. Patients with prior/current IE diagnosis at time of index valve surgery were excluded. Follow up was until 31 Dec 2018 with mortality and morbidity tracked from the respective death and APDC registries. Analyses based on Cox regression modelling included age, sex, background diagnoses and features of index valve surgery as time independent covariates, with any hospitalization (separately for specific invasive procedures) post index valve surgery as time dependent exposure covariates for risk of PVE within 6 months of exposure. Results: In total 23747 patients (median age [IQR] 73yo [65-79yo, 63% male) had cardiac valve surgery: 60% isolated aortic valve (n=15065), 28% isolated mitral valve (n=6702), 10% multiple valves (n=2385) and 1.5% right sided valves (n=357). 5.4% (n=1293) of patients experienced PVE at a median 2.9 years (IQR 0.7-6.2) after index valve surgery, with 65% (n=838) occurring within 6 months of any hospitalization. Any hospitalization exposure was associated with an adjusted hazard ratio of 4.0 for developing PVE (95% confidence interval 3.5-4.5). In addition, specific invasive procedures including repeat valve surgery were associated with an elevated risk for PVE (Figure). Conclusions: PVE is significantly more common after any hospitalization with specific invasive procedures carrying differential risk. Care should be taken to avoid unnecessary hospitalizations and procedures in these patients.