Background <p>Prosthetic valve endocarditis (PVE) is a life-threatening complication following valve replacement and is often challenging to diagnose in the early postoperative period. Coronary embolization is a rare manifestation of infective endocarditis, and PVE presenting as acute coronary syndrome is exceptionally uncommon.</p> Case presentation <p>A 73-year-old man underwent surgical aortic valve replacement with a 21-mm bioprosthetic valve. His postoperative course was uneventful, and he was discharged without anticoagulation therapy. One month later, he developed exertional dyspnea, gastrointestinal symptoms, and intermittent chest pain, which progressed to cardiogenic shock with severe bradycardia. Emergent coronary angiography revealed acute occlusion of the right coronary artery, and percutaneous coronary intervention was performed. Intravascular ultrasound and contrast-enhanced computed tomography revealed a low-echoic, low-attenuation lesion at the right coronary ostium, initially interpreted as thrombotic material. Despite successful revascularization, profound circulatory instability persisted. Subsequent echocardiography revealed prosthetic valve dehiscence with an annular abscess, confirming early PVE. Emergent surgery included annular reconstruction with a bovine pericardial patch, aortic root replacement, removal of the coronary stent, and coronary artery bypass grafting. Intraoperative hemodynamics remained unstable, necessitating postoperative veno-arterial extracorporeal membrane oxygenation support. The patient ultimately succumbed to non-occlusive mesenteric ischemia on postoperative day 10.</p> Conclusions <p>This case illustrates a rare and complex presentation of early PVE manifesting as acute right coronary artery occlusion. Coronary imaging alone may be insufficient to differentiate infected vegetation from thrombus. Early valve-focused echocardiographic evaluation is essential in patients with recent valve surgery presenting with acute coronary events.</p>