Mitral valve aneurysm (MVA) is a relatively rare but life-threatening condition that may occur as a complication of an infective endocarditis (IE) involved aortic valve. Rupture of the valve aneurysm is one of the most serious complications, which could result in severe mitral regurgitation and cause rapid hemodynamic deterioration, especially in heart failure patients. Timely diagnosis using echocardiography and appropriate treatments, such as invasive surgical repair or replacement of the valve, can effectively prevent catastrophic complications. Here, we present a 57-year-old male patient with MVA after IE and emphasize the key role of echocardiography in the early diagnosis and management of these kinds of conditions.