Infective endocarditis (IE) is a life-threatening condition caused by infection of the heart's endocardial surface, often involving native or prosthetic valves. It presents with diverse symptoms, ranging from isolated fever and heart failure to more severe manifestations such as ischemic stroke from septic or thrombus embolization. A rare but serious complication of IE is mitral valve aneurysm (MVA), a localized outpouching of the mitral valve, often leading to mitral regurgitation (MR), heart failure, and, in severe cases, rupture. This report highlights a case of delayed diagnosis of IE in a 34-year-old female who presented with prolonged fever, progressive dyspnea, and signs of heart failure. Echocardiography revealed severe MR, anterior mitral valve leaflet perforation, and a large pseudoaneurysm, suggesting MVA. Because of the advanced presentation, the patient developed refractory heart failure and electrical storm, leading to a fatal outcome before surgery could be performed. This case underscores the importance of early recognition of IE and MVA and the challenges in managing complicated cases, where mitral valve replacement is the preferred surgical option. Early diagnosis and timely intervention are crucial to prevent severe complications and improve prognosis.