A 70 year old woman with an unremarkable medical history was referred to our hospital for investigation of progressive dyspnoea and severe exercise intolerance.

Physical examination revealed a raised central venous pressure, pitting oedema of the lower limbs, and a loud, superficial and continuous murmur at the mid sternal border.

The ECG showed atrial fibrillation with a ventricular rate of 70/minute and an incomplete right bundle branch block. On chest x ray (panel A) the patient presented with cardiomegaly, suggesting dilatation of the right atrium. These findings were confirmed during echocardiography, showing also severe hypokinesia of the dilated right ventricle. A significant left-to-right shunt could be suspected by a continuous turbulent systolic and diastolic flow pattern at colour Doppler echocardiography. Coronary angiography (panels B and C) revealed a large aneurysm of the left main coronary artery with a coronary fistula originating in a dilated circumflex coronary artery and ending in the right atrium. The fistula was surgically closed and the patient is gradually recovering.

Communications between the coronary arteries and the cardiac chambers are caused by deviations from normal embryological development but they may also be acquired from trauma or from invasive cardiac procedures. The physiologic consequences depend on the termination site and the volume of the shunt. Symptoms can include myocardial ischaemia, heart failure, pulmonary hypertension, endocarditis, rhythm abnormalities, and, in rare cases, rupture of the fistula. Haemodynamically insignificant fistulae may not require further treatment but large, haemodynamically significant ones should be closed by surgery or percutaneous catheter techniques.

Chest radiograph: dilatation of the right atrium (RA).

Coronary angiogram: large aneurysm of left main coronary artery (LMCA) with coronary fistula (CF) originating (arrow) in dilated circumflex coronary artery (CX).

Coronary angiogram: fistula ending (arrow) in right atrium.