Introduction: Prosthetic valve endocarditis (PVE) is a severe complication in patients with both mechanical and bioprosthetic valves, occurring in 1-6% of patients with valve prosthesis and 10-30% of all infective endocarditis (IE) cases. Early PVE occurs during the first year after cardiac surgery. PVE has a very high in-hospital mortality rate of 20–40%. (1) We aimed to analyze PVE clinical, microbiological and echocardiographic features and outcomes in University Hospital Centre Zagreb during a two-year period (2016-2018).

Patients and Methods: A retrospective study was conducted. Patients diagnosed as „definite” or „possible“ IE according to modified Duke criteria were included and data from in-hospital charts and digital echocardiography database were analyzed. Outcomes were in-hospital mortality and reoperation (both urgent and elective).

Results: There were altogether 27 cases of IE: 19 (70.3%) men, median age 64 (range 28-84). PVE was found in 14 (51.9%) patients, among them there were 5 (35.7%) with aortic mechanical prosthesis, 6 (42.9%) with aortic bioprosthesis, one patient had a mitral mechanical valve and one bioprosthesis, while 2 (14,3%) had mitral valve repair. 6 (42.9%) occurred very early after valve surgery (within 60 days). Large vegetations (11.3±6.4 mm) were revealed by echocardiography in 12 (85.7%) PVE patients. Half of PVE patients (n=7) were referred to reoperation during initial hospitalization, with mortality rate of 14.3% (n=2). Isolated pathogens in blood culture were: coagulase negative Staphylococcus (n=5, 35.7%), Staphylococcus aureus (n=4, 28.6%), Enterococcus spp (n=2, 14.3%), Propionibacterium acnes (n=1) and Stenotrophomonas maltophilia (n=1). Culture-negative PVE was registered in one patient. IE valve involvement is shown in Figure 1.

Conclusion: We found an unexpectedly high incidence of PVE among IE patients (1, 2). Contrary, surgery-rate and in-hospital mortality were similar to published data (2). Most of the PVE in our patients occurred early after valve surgery and Staphylococcus spp is predominant isolated pathogen, as it was expected. Interestingly, regardless of prosthesis type, aortic position was predisposed to PVE.