Clinical and Prognostic Differences Between Mechanical Versus Biological Prosthetic Infective Endocarditis—A Nationwide Database Study

<b>Objectives</b>: Infective endocarditis (IE) is a feared and life-threatening complication, requiring a multidisciplinary approach. Prosthetic valve endocarditis (PVE) accounts for 20-30% of IE, is one of the most severe forms of IE, and is associated with high morbidity and mortality. We aim to compare and analyze baseline characteristics, microbiology, clinical presentation, complications, and prognosis between biological and mechanical PVE; we also carried out a subgroup analysis of patients aged 45-65 at the time of onset of prosthetic surgery. <b>Methods</b>: The present study is a post hoc analysis of a prospective multicenter cohort of patients with PVE between January 2008 and December 2023. Patients were divided into two groups regarding the type of prosthesis, mechanical vs. biological. <b>Results</b>: A total of 1544 patients were included. 733 (47.47%) patients with mechanical PVE (mPVE) and 811 (52.52) with biological PVE (bPVE). We found that bPVE appeared earlier than mPVE, had more healthcare-related infections and paravalvular complications. Both groups had similar clinical presentations; moreover, there was no difference in surgical indication and if surgery was performed. On the other hand, mPVE has a higher incidence of <i>Staphylococcus aureus</i> (SA) and Gram-negative bacteria, while bPVE has more coagulase-negative staphylococci. Multivariable logistic regression identified the following independent risk factors of mortality: EuroSCORE I, age, mPVE, SA, IE comprising two valves, and severe sepsis. mPVE had a higher mortality on admission, probably due to a higher incidence of septic shock and CNS embolism. The subgroup analysis of patients between 45 and 65 years at the time of prosthesis implantation showed similar results. <b>Conclusions</b>: The present analysis shows that bPVE appears earlier than mPVE, even in the subgroup of patients aged 45-65. bPVE has more healthcare-related infections and more paravalvular complications. After adjusting for baseline differences, mPVE had higher in-hospital mortality.