Misdiagnosed Isolated Ruptured Mycotic Mitral Valve Aneurysm as Mitral Annulus Calcification.

Introduction: Subacute Bacterial Endocarditis (SBE) is a slowly developing type of infective endocarditis. Aneurysm is more common in this type of endocarditis. Currently, SBE is an uncommon cause of unexplained fever (FUO) because rapid diagnostic capabilities, such as echocardiography, have improved. Despite echocardiography, endocarditis and valvular aneurysm were missed in our patient due to the location and special shape of the aneurysm near the annulus.

Case representation: We present a case of SBE resulting in an isolated ruptured mycotic mitral valve aneurysm in a patient on dialysis. Mycotic mitral valve aneurysm is an uncommon and serious complication of infective endocarditis, particularly subacute endocarditis.

Conclusion: In order to diagnose this complication, there should be clinical suspicion in the presence of severe regurgitation without any cause, and a detailed echocardiography should be performed.