Abstract 15206: Significance of Electrocardiogram Changes With Exercise in Pediatric Pectus Excavatum

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Introduction: The change in cardiac position caused by the thoracic deformity in patients with pectus excavatum (PEX) produces characteristic electrocardiogram (ECG) findings. However, the significance of ECG changes during exercise is unknown. Hypothesis: The ECG changes with exercise in PEX are related to worsening severity of PEX and location of PEX in relation to the heart. Methods: This was a retrospective review of patients ≤19 years old that underwent an institution-based protocol for preoperative PEX evaluation with ECG, echocardiogram (TTE), chest computerized tomography (CT) and cardiopulmonary exercise test (CPET) between January 2015 and December 2021. ECG changes with exercise were compared to the severity of PEX as defined by the Haller index (HI; mild = 2-3.2, moderate = 3.2-3.5, severe > 3.5) and location of the PEX as determined by right ventricular compression on CT. ECG changes were also compared to tricuspid valve annulus size (TVAS) on TTE and resting heart rate (HR) and HR reserve on CPET. Pearson's χ2 was used to compare categorical variables. Two-sample T-test was used to compare categorical with continuous variables. Results: There were 124 patients (85% male; median age 15 years [10-19 years]) with median HI 3.7 (2.4-20). Abnormal ECG changes with exercise were seen in 33 % of patients. Premature ventricular complexes (PVC) were the most frequently encountered (n=30; 73%). There was no significant difference in severity of PEX in patients with PVCs [χ2 =0.93, p 0.33; median HI of 3.9 (IQR 1.6) vs 3.7 (IQR 1.4)]. The majority of patients (96%) with PVCs had evident right ventricular compression on CT (χ2 = 5.20, p 0.02). Similarly, those with abnormal ECG changes with exercise were more likely to have a lower TVAS in comparison to those without [χ2 = 4.17, p 0.04; median TVAS z score -2.06 (IQR 1.22) vs -2.32 (IQR 0.75)]. The CPET indices were not significantly different between the two groups. Conclusions: The most frequent ECG abnormality seen with exercise in PEX in this cohort is PVCs. Lower TVAS and right ventricular compression on CT were significantly correlated with the development of PVCs with exercise. Follow-up evaluation of ECG during CPET after PEX repair may help affirm resolution of ectopy.