Coronary Artery Morphology and Function Late after Neonatal Arterial Switch Operation (ASO) for Transposition of the Great Arteries (TGA)—A Cardiac Magnetic Resonance (CMR) Study and Follow-up Recommendations

Objectives: Long-term follow-up after ASO can be complicated by myocardial ischemia due to stenosis, kinking or stretching of the reinserted coronary arteries (CA). We evaluated the potential advantage of CMR for noninvasive assessment of the CA.

Methods: A prospective study assessed insertion and proximal course of the CA by coronary MR angiography (MRA) and rate/extent of stress induced myocardial ischemia by dobutamine stress MR (DSMR). Of 92, 89 (97%) unselected patients (18–29 years) underwent CMR at rest (coronary MRA, cine), 85/92 (92%) DSMR (cine and perfusion), followed by late gad. e.(LGE).

Result: Coronary MRA: diagnostic in all patients, 88/89 (99%) had no stenosis or kinking of the proximal CA. One had known prox. LAD occlusion (collateralized via RCA). CA classification (Sauer): 72% A1 (normal type), 16% AB1 (CX retroaortal from right ostium), 2% A2 (left single ostium), 9% B1 (right single ostium, LCA retroaortal), 1% AB2 (RCA and CX inverted). Seven patients (8%) were reclassified compared with the operation report. LGE: no ischemic scar, 1 × intramyocardial fibrosis. DSMR: 79 of 85 (93%) reached target heart rate; 3 of 85 (3.5%) were pathologic: 1 ×  known prox. LAD occlusion (AB 1 with fct. single ostium, collateralized via RCA) with chest pain and hypokinesia in segment 1 under maximum Stress; 1 × single right CA ostium (reclass. AB1&→ B1) with complex VES and stress induced ischemia during DSMR, history of chest pain during school sports &→ coronary invasive angiography (CIA) without stenosis; 1 × dobutamine induced coronary spasm (A1) &→CIA without pathologic results.

Conclusion: A CMR coronary angiography in grown-ups after neonatal ASO for TGA is feasible to assess the proximal course of the reinserted coronary arteries noninvasively and without ionizing radiation. In addition to other noninvasive diagnostic procedures, it should be routinely performed at age 14 to 16 years in all young patients after neonatal ASO. Dobutamine stress MR represents the best possible form of simulation of a physiologic adrenergic exercise with increased cardiac work and movement for the coronary arteries. Due to the high incidence of normal results (96.5%), a routine DSMR in asymptomatic young adults after neonatal ASO does not seem necessary. In case of known abnormal coronary status or routine diagnostics and before starting with competitive sports, DSMR should be considered as a noninvasive feasible, safe, and meaningful additional diagnostic method without ionizing radiation.