Owing to abnormal chest x ray findings on a routine examination, a 40 year old lady was referred to the cardiology outpatient clinic. The chest radiograph demonstrated a prominence of the superior left heart border (the left atrium). There was no cardiovascular history. Physical examination revealed no abnormalities. The ECG showed normal sinus rhythm without evidence of left atrium enlargement.

Transthoracic echocardiography demonstrated a normal examination, except an impressive dilatation of the left atrial appendage. MRI scan (panel A) confirmed a 5.9 cm by 3.1 cm aneurysm of her left atrium appendage. No evidence of thrombus formation inside the appendage was detected on transoesophageal echocardiography (panel B). Doppler flow velocity in the left atrium appendage aneurysm was 45 cm/s, measured 1 cm under at the orifice and 25 cm/s at the bottom.

Magnetic resonance imaging scan. A coronal section. The * is placed in the left atrial appendage aneurysm.

Giant congenital intrapericardial aneurysm of the left atrium appendage is a very rare anomaly. Approximately 50 cases have been reported in the literature. Some patients may present with symptoms of angina pectoris, palpitations, or cerebrovascular accident—most are asymptomatic. Surgical resection is an option.

We did not found evidence of arrhythmias or thrombus formation in the left atrium appendage aneurysm. Therefore we opted for a conservative management. Although flow velocity was sufficiently high in the appendage aneurysm, the patient started oral anticoagulatant therapy and will be followed by echocardiography.

Transeosophageal echocardiograph. The * is placed in the 5.9 cm by 3.1 cm left atrial appendage aneurysm. The arrow is placed at the ostium of the appendage.