Coronary artery fistula is defined as any abnormal luminal connection between 1 or both coronary arteries and the cardiac chambers or great vessels.1 Coronary artery fistulae (CAFs) are a rare entity, found in 1 out of 50,000 live births and in 1 of 500 patients undergoing coronary angiography.2 They may be congenital or acquired and, clinically, can range from completely asymptomatic to florid congestive heart failure and ischemia with electrocardiogram (ECG) changes and other typical presenting complaints.
In the majority of cases, CAFs are isolated, but they can be associated with other anomalies in 20% to 45% of cases. Common associated anomalies include tetralogy of Fallot, atrial septal defect, patent ductus arteriosus, and ventricular septal defect. CAFs are an important component of pulmonary atresia with intact ventricular septum, as they can provide the only blood supply to areas of the left ventricle.3
Acquired CAFs can be a consequence of surgical or percutaneous intervention, trauma, or infection. Most cases are congenital malformations, although an increased incidence of CAF to the right ventricle has been observed in the heart transplant population due to repeated endomyocardial biopsy.4 The presence of a CAF places the patient at increased risk of bacterial endocarditis, myocardial ischemia, arrhythmias, coronary aneurysm with or without rupture, coronary atherosclerosis, and hypervolemic chamber overload.5
Coronary artery fistulas are classified according to the Congenital Heart Surgery Nomenclature and Database Project completed in 2000, which incorporates the prior angiographic classification schema of Sakakibara et al6 along with the etiology of the lesion (acquired vs congenital), vessel of origin, and site of drainage.2 In the era of percutaneous treatment, the morphology of the fistulous connection is also important to recognize. The condition was first treated in 1947 with surgical ligation, and in 1990, 2 separate groups first described transcatheter embolization of large coronary fistulas using both coils and detachable balloons.7,8 There is a paucity of clinical data supporting any particular treatment modality, although outcomes are favorable with both percutaneous and open surgical techniques.9-12 Current management favors catheter-based closure of these anomalies unless open fistula closure is to be performed as an adjunct to surgical correction of associated anomalies.
There are no clear guidelines regarding patient selection for fistula closure. Most authors agree that all symptomatic patients should be treated. There is no clear consensus regarding the management of asymptomatic patients. Criteria for closure of asymptomatic fistulae include presence of a systolic murmur, presence of a continuous murmur, and Qp/Qs >2.0 as a cutoff for significance, whereas others propose a shunt fraction greater than 1.5. Some groups recommend closure of fistulas >1.5 mm.13 Other authors have endorsed closure of all large fistulas to prevent future endocarditis14 or atherosclerosis.13 Some small fistulas in young patients will spontaneously close, and in low-risk cases, follow-up angiography could be considered.