Stress CT myocardial perfusion imaging after arterial switch operation for transposition of the great arteries

Coronary abnormalities are late complications of arterial switch operation for transposition of the great arteries (ASO-TGA) and may remain silent for decades. We evaluated the feasibility and diagnostic performance of stress CT myocardial perfusion imaging (CT-MPI) in adults after ASO.

Consecutive adults referred for clinically indicated coronary CT angiography (CCTA) underwent regadenoson stress CT-MPI using either dynamic energy-integrating detector CT (EID-CT) with quantitative myocardial blood-flow mapping or static photon-counting detector CT (PCCT) with qualitative and semiquantitative iodine-map assessment. All patients underwent stress cardiac magnetic resonance imaging (CMR) and invasive coronary angiography (ICA) within 3 months. Stress CMR served as the functional reference standard and ICA as the anatomical reference standard. Thirty-six patients were included (29 men; median age, 33.5 years), with 18 examined using each CT-MPI technique. Median neo-aortic diameter was 42 mm. At the per-segment level, CT-MPI achieved 95.5% sensitivity, 99.6% specificity, and 99.5% accuracy vs. stress CMR. In technique-stratified coronary-territory analyses, accuracy was 98.1% for static PCCT-MPI and 100% for dynamic EID-CT MPI. Against ICA, per-vessel sensitivity, specificity, and accuracy for obstructive coronary artery disease were 70.0%, 100%, and 98.6%, respectively. Coronary stenosis and a smaller coronary take-off angle were associated with ischaemia, whereas aortic dimension was not. A negative CT-MPI could have obviated additional testing in 30 of 36 patients (83.3%).

Stress CT-MPI combined with CCTA was feasible and demonstrated high diagnostic performance for detecting myocardial ischaemia after arterial switch operation. Larger prospective studies are needed to confirm these findings and define its clinical role.