Aneurysm of the mitral-aortic intervalvular fibrosa (MAIF) is an exceptionally rare but a potentially catastrophic complication, commonly following aortic valve endocarditis. We present a 24-year-old male presenting with acute onset dyspnea secondary to MAIF aneurysm rupturing into a left atrium causing large shunt which was diagnosed on echocardiography. The MAIF aneurysm in the absence of infective endocarditis rupturing into left atrium is extremely rare.