When Imaging Deceives: Recurrent Thromboembolic Strokes From Polymicrobial Bioprosthetic Valve Infection With Repeatedly Negative Transesophageal Echocardiography.

Prosthetic valve endocarditis (PVE) is a diagnostically challenging and frequently fatal infection in which echocardiography, the diagnostic cornerstone, is substantially less sensitive than in native valve disease. We describe a 67-year-old man with a bioprosthetic aortic valve who was hospitalized twice within three months, each admission characterized by polymicrobial bacteremia with Pseudomonas aeruginosa and Enterococcus faecalis, magnetic resonance imaging-confirmed bilateral thromboembolic cerebral infarcts, and septic shock. Transthoracic and transesophageal echocardiography (TTE/TEE) were performed during both hospitalizations and repeatedly failed to demonstrate valvular vegetations. Despite the absence of echocardiographic evidence of endocardial involvement, the clinical constellation of a prosthetic valve, persistent and recurrent bacteremia with biofilm-forming organisms, recurrent septic cerebral emboli, and failure of prolonged targeted antimicrobial therapy to achieve durable bacteremic clearance satisfied the modified Duke criteria for definite infective endocarditis (IE) on both admissions. This case underscores that a negative echocardiogram does not exclude PVE, that the modified Duke criteria enable a definite diagnosis when one major and three minor criteria are met, even when imaging is unrevealing, and that recurrent bacteremia with septic embolization in a patient with prosthetic material constitutes a compelling indication for surgical source control irrespective of echocardiographic findings. After multidisciplinary evaluation, the patient was transferred to a tertiary center for consideration of valve explantation. Clinicians must resist anchoring on false-negative imaging and allow the totality of clinical, microbiological, and radiographic data to guide definitive management.