Discussion

Infants with coronary artery fistula may be asymptomatic, except for heart murmur on routine examinations, or be recognised by symptoms with heart failure – tachypnoea or tiredness during feeding. Major sites of origin of the fistula are from the right coronary artery, and termination of the fistula is on the right side of the heart. Some studies have considered early treatment in infants with therapeutic transcatheter embolisation or surgical intervention to prevent the fistula from enlarging progressively over time and complications – congestive heart failure, myocardial ischemia or infarction, arrhythmias, infectious endocarditis, aneurysm formation or rupture, and death.Reference Hsieh, Huang and Lee ^{1 ,} Reference Valente, Lock and Gauvreau ² The neonates who were diagnosed with coronary artery fistula prenatally show higher chances of developing associated symptoms and complications, and transcatheter or surgical closure of the fistula was suggested in a timely manner.Reference Hayashi, Inuzuka, Ono and Katori ³

In this paper, we report a case of congenital right coronary artery to left atrium fistula with heart murmur and mild congestive heart failure after birth. The fistula was revealed to close spontaneously under 2.5 months of age by echocardiography followed by disappearance of the murmur. The proximal fistula was still dilated. Because congenital coronary artery fistula may close spontaneously in <3 months after birth as in our case, the incidence of congenital coronary artery fistula will be underestimated and the treatment of that should be more observation than intervention. Because of the incomplete resolution of the coronary artery fistula, the long-term outcome of thrombosis and myocardial ischemia or infarction should be evaluated in such patients.

The postulations of mechanism responsible for spontaneous closure of coronary artery fistulas are (1) a high flow leading to shear-induced endothelial damage, leading to premature atherosclerosis and thrombosis at the level of narrow fistulous communication with the heart; (2) fibrosis; and (3) local myocardial hypertrophy.Reference Schleich, Rey, Gewillig and Bozio ^{4 ,} Reference Hackett and Hallidie-Smith ⁵

As the natural course of coronary artery fistulas is still poorly known, and cases of spontaneous closure are eligible for transcatheter or surgical intervention to prevent the development of potentially fatal complications, it is worth reconsidering the attitude of observationReference Yilmazer, Demir, Yolbaş and Bilici ⁶ than intervention. We suggest that planned duration and frequency of follow-up may be of value.

Following congenital coronary artery fistula closure either via spontaneous regression or intervention with surgery or transcatheter, aneurysm formation is a potential risk factor for thrombotic complications after closure. The long-term evaluation of the coronary artery and use of anticoagulation after fistula closure should be considered.Reference Gowda, Latson, Kutty and Prieto ^{7 ,} Reference Miyamura, Eguchi and Watanabe ⁸

In summary, neonates with congenital coronary artery fistula may be asymptomatic or with heart failure. Some studies have considered early treatment in infants with therapeutic transcatheter embolisation or surgical intervention to prevent the fistula from enlarging progressively over time and complications. In this paper, we report a case of congenital right coronary artery to left atrium fistula with heart murmur and mild congestive heart failure after birth. The fistula was revealed to close spontaneously under 2.5 months of age, but the proximal fistula was still dilated. The incidence of congenital coronary artery fistula may be underestimated. Owing to incomplete resolution of coronary artery fistula, the long-term outcome of thrombosis and myocardial ischemia or infarction should be evaluated in such patients.