Importance of Coronary to Pulmonary Artery Fistulae Incidentally Detected on Echocardiography: Can We Ignore It During Childhood?

BACKROUND: Coronary artery fistula (CAF) is an abnormal precapillary connection between a coronary artery and an adjacent structure. The incidence of CAF in children as estimated from echocardiography is 0.06-0.2%. We aimed to establish the follow up results of clinically silent CAF found incidentally by colour Doppler echocardiography. METHODS: The study included patients with abnormal fistulous flow in the pulmonary artery who had been studied between 2008 and 2020. Patient demographics, clinical findings, indication for echocardiography, electrocardiographic findings at presentation, follow-up times and any fistula progress were obtained from the recorded files. RESULTS: Among the 78,000 patients who had had an echocardiographic examination, 118 had been found by colour Doppler flow mapping to have a clinically silent CAF. The exit point of CAF was clearly visualized with colour Doppler in all patients. In most patients the CAF was located around the pulmonary valve and the bifurcation; in 76 patients, it was on the aortic side of the main pulmonary artery, 26 patients had fistulous flow through the anterior wall of the main pulmonary artery, two had the right ventricular outflow tract (RVOT) as the exit site, for 12, it was the right pulmonary artery, and for another two, the left pulmonary artery. The 118 patients had ongoing follow-up to mean 41 months. There was no spontaneous resolution of fistula. The patients were asymptomatic without intervention and with ongoing echocardiographic evidence of small CAF at the last follow-up. CONCLUSION: We recommend the treatment strategy for paediatric patients should be individualized according to fistula origin, size, chamber enlargement, draining site, age of the patient and cost of imaging during follow up.