Infective Endocarditis in Patients With Bicuspid Aortic Valves: Unique Clinical and Microbiologic Features.

Objective: Patients with bicuspid aortic valves (BAV) are at increased risk of infective endocarditis (IE). Information of the clinical presentation and the microbiology of BAV-associated IE, however, is limited. Therefore, our study aimed to characterise the clinical features native valve endocarditis (NVE) in the setting of BAV and compared them to patients with prosthetic valve endocarditis (PVE) following BAV replacement.

Methods: Adult patients with BAV or history of BAV with aortic valve replacement (AVR) and a definite or possible IE diagnosis within the Mayo Clinic Enterprise (USA) from January 2008 to December 2021, were included. BAV was confirmed by trans-oesophageal echocardiography. IE was defined according to the modified Duke criteria and only an initial episode was included. Statistical analyses were performed to compare clinical characteristics, microbiology, and IE complications.

Results: Overall, 161 patients with BAV and IE (NVE [n=60], 37.3%) and PVE [n=101, 62.7%) were included. Mean age±SD was 56.5±16.1 years, and 139 (86.3%) patients were males. PVE patients were older (p<0.01) and had a higher rate of hypertension (p<0.01), chronic heart failure (p<0.01), chronic kidney disease (p<0.01), and perivalvular abscess (p<0.01). BAV patients with NVE had a higher prevalence of isolated mitral valve IE (p<0.01), moderate to severe aortic valve regurgitation (p<0.01) and combined aortic with mitral valve IE (p<0.01). Streptococcus mitis was the most common pathogen in NVE (30.0%) while Staphylococcus aureus was the most common in PVE (15.8%).

Conclusions: Patients with BAV are at risk of both NVE and PVE. Each syndrome has unique clinical features, including microbiologic findings, that should be appreciated in IE diagnosis and management.