Background: Coronary artery fistulas are rare congenital or acquired coronary artery anomalies that can originate from any of the three major coronary arteries and drain in all the cardiac chambers and great vessels.
Case presentation: An 11-year-old boy was referred for evaluation of an exertional dyspnoea. He reported recent history of few episodes of shortness of breath associated with moderate entity physical activity. At physical examination a mild continuous murmur could be heard mainly at the level of the second intercostal space of the left parasternal area. A transthoracic echocardiogram showed a continuous flow at color Doppler analysis in the high parasternal short axis view, originating from a small entry site on the wall of the main pulmonary artery. A selective left coronary angiography revealed a fistula connecting the proximal portion of the left anterior descending coronary artery with the main pulmonary artery.
Conclusion: A combination like the one described in the present case is unusual since fistulas originate from the left coronary artery in about 35% of cases and drainage into the pulmonary artery occurs in only 17%.