To assess the functionality of congenital coronary artery fistulas (CAFs) using adenosine stress 13N-ammonia positron emission tomography computed tomography (PET-CT).

Congenital CAFs were incidentally detected during coronary angiography (CAG) procedures in 11 adult patients (six males and five females) with a mean age of 64.3 years (range 41-81). Patients were collected from three institutes in the Netherlands. The characteristics of the fistulas (origin, pathway and termination), multiplicity of the origins and pathways of the fistulous vessels were assessed by CAG. Five patients underwent adenosine pharmacologic stress 13N-ammonia PET-CT to assess myocardial perfusion and the functional behavior of the fistula.

Eleven patients with 12 CAFs, 10 unilateral and one bilateral, originating from the left anterior descending coronary artery (n = 8), right coronary artery (n = 2) and circumflex (n = 2). All fistulas were of the vascular type, terminating into either the pulmonary artery (n = 11) or coronary sinus (n = 1). The CAG delineated the characteristics of the fistula (origin, pathway and termination). Multiplicity of the origins and pathways of the fistulous vessels were common in most fistulas (8/12, 67% and 9/12, 75%, respectively). Multiplicity was common among the different fistula components (23/36, 64%). Adenosine pharmacologic stress 13N-ammonia PET-CT revealed normal myocardial perfusion and ejection fraction in all but one patient, who showed a reduced ejection fraction.

PET-CT may be helpful for assessing the functional status of congenital CAFs in selected patients regarding clinical decision-making. Studies with a larger patient series are warranted.

We present two cases where fractional flow reserve (FFR) was utilised to guide management of coronary artery fistula (CAF), an approach advocated in recent case studies. CAF is a coronary anomaly that may present with a variety of syndromes though is frequently asymptomatic. When to exclude the fistula (surgically or percutaneously) is not always clear. A way to quantify if the fistula is physiologically meaningful would be advantageous. Our findings suggest FFR may only be assessing the concomitant epicardial coronary artery disease (CAD) rather than the degree of coronary steal and its routine use in this setting is not supported.