Congenital Left Atrial Mitral Accessory Chord With Accessory Mitral Valve Tissue Causing Dual-Valve Regurgitation

Left atrial mitral valve (MV) accessory chord and accessory MV tissue are rare congenital anomalies that may mimic more common pathologies.

A 30-year-old man presented with dyspnea, weight loss, and an outpatient transthoracic echocardiogram concerning for infective endocarditis. Transesophageal echocardiography revealed a chordlike structure extending from the limbus of the interatrial septum to the anterior MV leaflet, continuing through the left ventricular outflow tract, across the aortic valve, and into the ascending aorta. These findings were associated with moderate mitral regurgitation and severe aortic regurgitation. Surgical resection confirmed the diagnosis of accessory MV tissue with a left atrial MV accessory chord.

Patients may present with heart failure or malperfusion symptoms due to valvopathy or left ventricular outflow tract obstruction. Multimodal imaging and surgical resection with valve repair are key to diagnosis and management.

Chordal anomalies can mimic endocarditis and cause dual-valve disease. Early transesophageal echocardiography and surgical intervention are critical to avoid misdiagnosis.