<p>This study aimed to evaluate the frequency of cardiovascular implantable electronic device (CIED) programming changes in pediatric and/or congenital heart disease (CHD) patients based on evaluation at the time of an exercise stress test (EST). Arrhythmia frequency during EST was also recorded. Single center retrospective chart review was performed in pediatric and/or CHD patients with CIEDs who completed ESTs under direct pediatric electrophysiology supervision from January 2018 to May 2022. CIED interrogations and EST findings were recorded to investigate the frequency of programming concerns and/or adjustments as well as arrhythmia frequency. 119 patients with ESTs; 86.6% patients had a pacemaker, 13.4% with an implantable cardioverter defibrillator. 38.7% of patients had changes made to their device programming. The most common adjustments made were device rate related parameters (14.3%) such as atrioventricular delay and upper tracking rate, rate responsiveness (12.6%), and output changes (12.6%). Patients with rate responsiveness turned on were more likely to have programming changes. 65.6% of patients had ectopy or arrhythmias during their EST. Notable ectopy and arrhythmias occurred frequently including 5.9% premature ventricular contractions at peak exercise, 10.9% with complex ventricular ectopy, and 2.5% with non-sustained ventricular tachycardia. Patients on an anti-arrhythmic medication were more likely to have complex ventricular ectopy. This study provides evidence that ESTs are an important component of management in patients with CIEDs. Ectopy and arrhythmias are common in pediatric and CHD patients with CIED who complete ESTs. Knowledge of a patient’s anti-arrhythmic medications may assist in risk stratification.</p>