Purpose or Case Report: Coronary artery abnormalities are a serious complication following the arterial switch operation (ASO) for d-transposition of the great arteries (TGA). While CTA optimally visualizes the coronaries, prior studies have found potentially high-risk coronary lesions in asymptomatic s/p ASO patients, raising questions about when CTA is warranted. CMR is commonly used for monitoring after the ASO, offering assessment without radiation. However, its utility for coronary evaluation remains unclear. We aimed to (1) compare the indications and outcomes of CMR vs. CTA after ASO, and (2) compare coronary features between modalities.
Methods & Materials: Patients with TGA s/p ASO underwent CTA (n=25, 8.6±6.9 yrs) or CMR (n=64, 13.7±4.2 yrs) between 2012 and 2024. Imaging indications, coronary findings, and outcomes were reviewed. For 10 patients with both CTA and CMR, coronary anatomy, including branch pattern, dominance, interarterial course, origin dimensions, take-off angles, and proximal angulation, was evaluated and compared between modalities.
Results: The prevalence of coronary abnormalities detected on CTA and CMR that required further evaluation was low (0.03%, n=89). Coronary concerns were more frequently a CTA indication (24.2%) compared with CMR (7.69%, p=0.03). CTA was often used with high suspicion for a coronary abnormality, whereas CMR was often used for broader cardiac evaluation when coronary abnormalities were less likely. Among CMR studies with a coronary indication (n=28), no coronary findings required further workup or intervention. Among CTA studies with a coronary indication (n=12), two (17%) found coronary abnormalities needing further evaluation, including one case of coronary aneurysms requiring anticoagulation. In a subcohort of 10 patients with CTA and CMR, there was agreement between modalities on coronary dominance and branching for all patients, and on presence or absence of interarterial course for 8 patients. For 2 patients, interarterial course of the left coronary artery was found on CTA and was suspicious but indeterminate on CMR. Coronary dimensions were slightly larger on CMR, with significant differences for left main (p=0.049), right (p=0.02), and circumflex (p=0.049) origins. No significant differences were observed for coronary take-off angles or proximal angulation.
Conclusions: In TGA s/p ASO, CTA is preferred when coronary abnormalities are highly suspected, whereas CMR is more frequently performed for monitoring. Both modalities generally agree on coronary anatomy.