Congenital coronary fistulas are very rare CHD, the aim of sharing this case is to show the images in a child with a giant coronary fistula who had a good outcome with percutaneous treatment.

Male aged 5 years was referred for evaluation of a cardiac murmur present since birth. He was in functional class I. Physical examination revealed a continuous mesocardial murmur with marked thrill and bounding pulses. Chest radiography showed cardiomegaly (cardiothoracic ratio 0.58) with increased pulmonary flow. Electrocardiography demonstrated sinus rhythm with rightward QRS axis and no significant ST abnormalities. Although patent ductus arteriosus was initially suspected, the murmur's location was atypical.

Transthoracic echocardiography identified a giant coronary fistula arising from the left anterior descending coronary artery draining into the right ventricle. Additional findings included moderate aortic root dilatation, mild aortic regurgitation, preserved biventricular systolic function, and mild basal anteroseptal hypokinesia. Computed tomography angiography confirmed a giant congenital coronary fistula measuring 18 mm at its largest diameter and 13.5 mm at its smallest.

Congenital coronary fistulas are rare, representing 0.05–0.25% of congenital heart disease. Most patients remain asymptomatic; however, a continuous mesocardial murmur is an important clinical clue regardless of fistula size.

Considering the risk of progressive myocardial ischemia and heart failure, percutaneous closure was selected. Cardiac catheterization confirmed the anatomical findings, and the fistula was successfully occluded using a 20-mm Amplatzer Vascular Plug II. Final angiography demonstrated only mild residual leakage, while volume-rendered reconstruction confirmed effective occlusion. The postoperative course was uneventful. At six-month follow-up, the patient remained asymptomatic, with no residual shunt or procedure-related complications, demonstrating an excellent short-term outcome after transcatheter treatment. This case highlights the diagnostic value of multimodality imaging for defining anatomy, guiding therapeutic planning, confirming procedural success, and supporting durable clinical improvement in children with complex congenital coronary artery fistulas during follow-up.

Javier De la cruz-Pelayo completed his MD. at the age of 32 years from National Autonomous University of Mexico, Mexico. He is the head of the Cardiovascular Imaging department of Institute for the Social Security and Social Services of State Employees (ISSSTE), Tlajomulco City, Jalisco, Mexico