When imaging speaks louder than symptoms: a case report

Late prosthetic valve dehiscence is a rare but life-threatening complication, most commonly associated with infective endocarditis. Low-virulence organisms such as Cutibacterium acnes can cause indolent infections with minimal clinical signs, making diagnosis particularly challenging.

A 64-year-old man with a history of surgical aortic valve replacement with a mechanical prosthesis (2006) was admitted for elective VVI pacemaker implantation due to permanent atrial fibrillation with slow ventricular response and suspected intermittent complete atrioventricular block. During the procedure, fluoroscopy incidentally revealed abnormal mobility of the aortic prosthesis, raising suspicion for valve dehiscence. Transthoracic and transoesophageal echocardiography confirmed significant prosthetic rocking without relevant paravalvular regurgitation. Urgent surgical re-exploration demonstrated near circumferential dehiscence of the prosthesis. The valve was explanted and replaced with a bioprosthesis. Microbiological cultures of valve tissue and blood grew Cutibacterium acnes, consistent with chronic prosthetic valve endocarditis. The postoperative course was uneventful, and the patient was discharged on targeted antibiotic therapy. At 6-week follow-up, he remained asymptomatic with normal prosthetic valve function.

This case highlights a rare presentation of late mechanical prosthetic valve dehiscence due to indolent Cutibacterium acnes infection in the absence of overt clinical signs. It underscores the diagnostic value of incidental imaging findings and the need for a high index of suspicion for low-grade infective endocarditis in patients with prosthetic valves, even many years after implantation.