Association of lower noninvasive fractional flow reserve values with high risk anatomic characteristics in pediatric patients with anomalous coronary arteries.

Background: Although there are data on fractional flow reserve CT (CT-FFR) assessment for anomalous aortic origin of coronary artery (AAOCA) in adults, reports in children are limited.

Methods: Cardiac CT angiograms of patients ages 4-21 years with AAOCA performed from 2010 to 2021 ​at a single center were retrospectively identified. Characteristics historically considered high-risk -slit-like ostium, interarterial course, or intramural segment-, symptoms suggestive of ischemia, or positive provocative testing were correlated with reduced CT-FFR values of <0.8 and ​< ​0.9. Distribution of CT-FFR values in patients with and without high-risk characteristics were compared.

Results: CTAs for 39 patients, median age 14.3 (interquartile11.4-15.8) were of adequate quality for analysis. In anomalous right (ARCA) patients (n ​= ​30), rates of interarterial course, intramural course and acute takeoff angle were each 83.3 ​%; 80 ​% had slit-like orifice. In anomalous left (ALCA) patients (n ​= ​9), 77.8 ​% had an intramural segment, 77.8 ​% acute takeoff angle, and 66.7 ​% interarterial course; none had slit-like orifice. CT-FFR values were significantly lower in patients with ARCA and high-risk anatomic characteristics. There was no significant correlation between high-risk characteristics or intramural length, and abnormal FFR with cutoff of <0.8. With cutoff <0.9, there was correlation between slit-like orifice and abnormal RCA and circumflex CT-FFR. In patients with ARCA, intramural length correlated negatively with RCA CT-FFR value (rho ​= ​-0.67, p ​< ​0.0001).

Conclusion: CT-FFR values are lower in patients with ARCA and anatomic characteristics considered high-risk. A cutoff CT-FFR value of <0.9 correlated with slit-like orifice. Further studies are needed to show utility of CT-FFR in guiding management of AAOCA in children.