Abstract 12511: Exercise Stress Test and Myocardial Perfusion Imaging Have Limited Diagnostic Reliability in Detecting Coronary Abnormalities in Children After Arterial Switch Operation for Transposition of the Great Arteries

Abstract

Background: Exercise stress test (EST) and myocardial perfusion imaging (MPI) are common non-invasive modalities to screen for occult myocardial ischemia, but their sensitivity and specificity in children are unknown. Hypothesis: EST and MPI have limited sensitivity and specificity in detecting occult myocardial ischemia in children. Patients and Methods: We retrospectively reviewed EST, MPI, and coronary angiogram in asymptomatic patients after arterial switch operation (ASO) for d-transposition of the great arteries (TGA) and examined the sensitivity and specificity of EST/MPI in detecting coronary abnormalities. Positive ECG findings for exercise-induced ischemia included ST-T depression > 2mm and exercise-induced ventricular ectopies. Positive MPI is defined as a perfusion defect. Data are shown as mean ± SD. Results: Thirty asymptomatic patients (20 male/10 female; 23 with intact ventricular septum and 7 with ventricular septal defect; ages 12.5 ± 4.4 years) had EST and 26 had simultaneous MPI. Respiratory quotient was 1.11 ± 0.07 and maximum oxygen consumption was 80.7 ± 15.0% predicted, suggesting mildly diminished aerobic fitness level. There was no exercise-induced arrhythmia. Twenty two patients had coronary angiogram (Table 1). Four patients with positive EST and/or MPI were confirmed to have coronary abnormalities by coronary angiogram, whereas 4 patients revealed variable degree of coronary obstruction despite negative EST/MPI including 1 patient who later developed life-threatening ventricular fibrillation. Three patients with positive EST or MPI showed no coronary abnormalities. Conclusions: A combination of EST and MPI has low sensitivity (50%; 4/8) and moderate specificity (79%; 11/14) in detecting coronary abnormalities after ASO. Thus, we recommend performing coronary angiography or equivalent coronary investigation in addition to EST/MPI in children after ASO to detect coronary abnormalities and myocardial ischemia.