Identifying Subclinical Coronary Abnormalities and Silent Myocardial Ischemia After Arterial Switch Operation

The incidence of late coronary complications is reported around 8% after arterial switch operation (ASO) for d-transposition of the great arteries, but the affected patients are usually asymptomatic. Exercise stress test (EST) and myocardial perfusion imaging (MPI) are common non-invasive modalities to screen for silent myocardial ischemia, but their diagnostic reliability in children after ASO is unclear. We retrospectively reviewed asymptomatic patients following ASO with EST, MPI, and coronary imaging studies (CIS) and examined the reliability of each test in identifying abnormal coronary lesions responsible for myocardial ischemia. Thirty-seven asymptomatic patients (24 males; ages 12.7 ± 3.7 years) had EST, in which 27 and 33 patients also underwent MPI and CIS, respectively. Exercise capacity was comparable to the age- and sex-matched 37 controls. In seven patients with angiographically proven moderate to severe coronary abnormalities, only two patients had positive EST and/or MPI, and five patients were negative including one patient who later developed exercise-induced cardiac arrest due to severe proximal left coronary artery stenosis. Two patients with positive EST or MPI showed no corresponding coronary abnormalities by CIS. Occurrence of acquired late coronary abnormalities did not correlate with the original coronary anatomy or initial surgical procedures. There is no single reliable method to identify the risk of myocardial ischemia after ASO. Although CIS are regarded as a gold standard, multidisciplinary studies are essential to risk-stratify the potential life-threatening coronary lesions after ASO in children.