Exercise-induced ectopy and its relationship to fitness, cardiac function, and markers of severity in youth with pectus excavatum

Patients with pectus excavatum (PE) are at increased risk of cardiac derangements, including cardiac arrhythmias. Little is known about exercise-induced ectopy in pediatric patients with PE and how it relays to pulmonary function testing (PFT), cardiac magnetic resonance imaging (CMR), CPET, and PE anatomic indices during rest. This retrospective cohort study (Level of Evidence II) analyzed 661 patients with PE. Patient ECGs were categorized by frequency and presence of either atrial or ventricular ectopy. Patients were then split into complex/frequent ectopy (defined as frequent isolated ectopy or ≥4 beats of ventricular or atrial tachycardia) vs noncomplex/infrequent ectopy. Each group had PFTs, cardiac imaging, and PE anatomic indices compared using a student's t-test. P<0.05 was considered significant. We observed ventricular ectopy in 34.9% of patients and atrial ectopy in 16.9%. Those with a complex ventricular ectopy had significant differences in their Haller Index (6.2±2.4 v 5.2±2.7; p=0.02), correction index (41.4±14.4 v 30.8±15.5%; p<0.0001), and depression index (0.77±0.05 v 0.58±0.01; p=0.0002). Patients with complex ventricular ectopy also had significantly lower left ejection fraction (56.8±3.0 v 58.5±4.0%; p=0.009). Ventricular tachycardia occurred in 2.6% of patients. Those with ventricular tachycardia had a low peak oxygen consumption (75.5±13.2 v 87.3±16.9%; p=0.004) and left ventricular ejection fraction (55.6±2.2 v 58.5±4.0%; p=0.003). Ventricular ectopy is common during exercise in pediatric patients with PE, and those with higher CMR markers of structural severity had more complex ventricular ectopy.