Enterococcal Endocarditis in a Bicuspid Aortic Valve Associated With a Sinus of Valsalva Aneurysm.

This report describes a complex case of Enterococcus faecalis infective endocarditis (IE) in a 68-year-old man with an undiagnosed bicuspid aortic valve (BAV) and a concomitant sinus of Valsalva aneurysm (SoVA). A significant diagnostic challenge occurred as the patient's initial febrile illness was misattributed to Lyme disease; two subsequent 30-day courses of doxycycline partially treated the infection, masking the clinical severity and delaying diagnosis. The patient eventually presented with new-onset atrial fibrillation, heart failure, and a new bifascicular block. Transesophageal echocardiogram (TEE) revealed a bulky vegetation on the BAV, leaflet perforation, and severe aortic regurgitation, alongside a perivalvular aortic root abscess. Despite the diagnostic delay and anatomical complexity, the patient was successfully managed with urgent aortic valve and root replacement (Bentall procedure) and the placement of a leadless pacemaker for postoperative complete heart block. This case illustrates the "perfect storm" of high-risk anatomy (BAV and SoVA) and antibiotic-induced diagnostic masking, emphasizing that new conduction abnormalities or heart failure in febrile patients must trigger immediate TEE to identify perivalvular extension.