Ventricular arrhythmias during exercise testing in pediatric patients with arrhythmogenic cardiomyopathy at first presentation and with different ventricular involvement.

Background: Ventricular arrhythmias (VAs) may be the first clinical manifestation in pediatric patients with arrhythmogenic cardiomyopathy (ACM). The arrhythmogenicity of exercise testing (ET) remains unclear.

Objective: The aim of this study was to describe the arrhythmogenicity of ET in pediatric early ACM.

Methods: Pediatric patients diagnosed with definite ACM were enrolled. ET results at the first presentation and after discontinuation of therapy were analyzed. Comparison with a control group (premature ventricular complexes [PVCs] without structural heart disease) was performed.

Results: At baseline, VAs were observed in 20 (80%) patients; 3 had nonsustained ventricular tachycardia and 17 had isolated PVCs. No PVC morphology was significantly more prevalent in ACM phenotypes. At peak exercise, VAs were present in 40% of patients and 10% of controls. During recovery, VAs occurred in 17 (68%) patients and 4 (8%) controls. Polymorphism and nonsustained ventricular tachycardias during recovery were more prevalent in biventricular ACM (BIV-ACM) than in non-biventricular ACM (P = .03; P = .03). Irregular VAs were present in 80% of BIV-ACM. Compared with controls, PVCs with left bundle branch block-superior axis at baseline and VAs during recovery were significantly associated with the probability of having ACM (P = .0038, P < .0001, respectively).

Conclusions: The behavior of VAs during ET at the beginning of ACM is highly variable, and suppression during exercise is not uncommon. Nevertheless, presence at the peak of exercise is more common in ACM patients. Baseline left bundle branch block-superior axis PVCs and VAs during recovery correlate with the presence of ACM. VA morphology and ET behavior cannot predict ACM phenotype. Polymorphism and nonsustained ventricular tachycardias are more prevalent in patients with BIV-ACM.