Noninvasive Anatomical and Functional Imaging for Hemodynamic Relevance in Right Coronary Artery Anomalies

Right anomalous aortic origin of a coronary artery (R-AAOCA) is a rare congenital condition increasingly diagnosed with the growing use of cardiac imaging. Due to dynamic compression of the anomalous vessel, invasive fractional flow reserve (FFR) during a dobutamine-atropine volume challenge (FFR-dobutamine) is considered the reference standard. A reliable alternative method is needed to reduce extensive invasive testing, but it remains uncertain whether noninvasive imaging can accurately assess the hemodynamic relevance of R-AAOCA.

To evaluate the diagnostic performance of noninvasive anatomical and functional cardiac imaging to determine the hemodynamic relevance of R-AAOCA compared with the FFR-dobutamine reference standard.

This was a prospective, single-center cohort study performed between June 2020 and January 2025. The study was conducted at a specialized coronary artery anomaly clinic in Bern, Switzerland. Consecutive adult patients with R-AAOCA with an interarterial/intramural course and a right coronary dominance were included in the study.

All patients underwent coronary computed tomography angiography (CCTA), nuclear cardiac imaging, and invasive FFR-dobutamine testing.

Hemodynamic relevance of the anomalous vessel was defined as an FFR-dobutamine value less than or equal to 0.8. Patients with stenotic atherosclerotic plaques in the anomalous vessel at the time of functional testing were excluded.

A total of 55 patients (mean [SD] age, 51 [12] years; 37 male [67%]) with newly detected R-AAOCA and combined interarterial/intramural course were included in the analysis. Median FFR-dobutamine was 0.87 (IQR, 0.80-0.91), and 15 cases (27%) were hemodynamically relevant (ie, FFR-dobutamine ≤0.8). Anatomical CCTA (ie, CCTA-ostial minor axis) assessment demonstrated both a 100% sensitivity and negative predictive value with a receiver operating characteristic curve of 0.82, as well as a specificity of 57%, leading to rule out 23 cases (42%; ie, 58% of the hemodynamic nonrelevant cases). Functional nuclear imaging detected ischemia in 4 patients (7%; ie, 27% of hemodynamically relevant cases, all true positive, none false positive), resulting in a sensitivity of 27%, both specificity and positive predictive value of 100%, and an accuracy of 80% in predicting FFR-dobutamine less than or equal to 0.8.

Results of this cohort study suggest that in adults with R-AAOCA, a multimodality diagnostic imaging approach applicable in a stepwise manner, starting with CCTA, which offers high diagnostic performance to exclude hemodynamic relevance-and optionally complemented by functional imaging with modest diagnostic performance to rule in hemodynamic relevance-may help to reduce the need for invasive testing to a subset of patients.