A 53-year-old Japanese man presented with severe chest pain. He had suffered from persistent fever, muscle pain, arthralgia, and dyspnea on exertion (New York Heart Association class I) for two and half months prior to admission. He had been treated with several antibiotics for two months and prednisolone for almost one month prior to admission. On the day of admission, he had suffered from chest pain at rest, and had come to our hospital. Electrocardiography showed a normal sinus rhythm with significant ST segment elevation in leads V3-6 and abnormal Q waves in leads V4-6. Transthoracic echocardiography demonstrated left ventricular ejection fraction of 52% with severe mitral regurgitation and an 18-mm vegetation on the anterior mitral valve leaflet. Multiple blood cultures identified Streptococcus sanguis. The diagnosis was acute myocardial infarction and mitral regurgitation associated with infective endocarditis (IE). The incidence of acute coronary syndrome caused by IE is quite low in patients with native valves. After a 6-week course of antibiotics, mitral valve replacement and partial cardiomyotomy were performed. Two years after the surgery, follow-up echocardiography showed almost normal left ventricle function and no mitral regurgitation, and the patient has been living an active life without any complications.
Keywords: Infective endocarditis; Myocardial infarction; Septic emboli.