B-po05-167 atrial tachyarrhythmias in catecholaminergic polymorphic ventricular tachycardia: a report from the international pediatric cpvt registry

While Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is typically characterized by adrenergic-induced bidirectional or polymorphic ventricular tachycardia, atrial arrhythmias also occur. However, little is known about this manifestation. To compare demographics and outcomes of pediatric CPVT patients with and without atrial tachyarrhythmias (AT). In this prospectively followed pediatric CPVT population, we compared baseline demographics, therapy, genetics and outcomes in patients <19 years old with and without AT. Eighty patients without AT were compared to 27 patients with AT, identified during treadmill (n=11), Holter (n=7), epinephrine/isoproterenol (n=6) testing and device interrogation (n=3). Fifteen patients (56%) had atrial tachycardia, 11 (41%) had atrial fibrillation, and 1 (4%) had an ectopic atrial rhythm. Of these patients, 1 had sinus node dysfunction necessitating a pacemaker. Median age at presenting symptom in the AT group was 6.5 (IQR: 4-9.3) years vs 11 (IQR: 7-14) years in the non-AT group (p<0.001). Sex, proband status and baseline therapy did not differ significantly between groups. Combination therapy (flecainide and β-blocker) was used in 15 AT patients and was ineffective in controlling AT in 56% (5 of 9) with follow-up data. Catheter ablation for AT was unsuccessful in 3 of 5 (60%) patients. In the AT group, 10 of 24 (42%) patients with genetic testing had a likely pathogenic/pathogenic RYR2 variant vs 46 of 76 (61%) in the non-AT group (p=0.16). The rate of life-threatening cardiac events (death, cardiac arrest, syncope, appropriate ICD discharge) during follow-up for AT patients was 48% (13 of 27) vs 34% (27 of 80) in the non-AT group (p=0.25). One quarter of pediatric CPVT patients had AT, which were associated with younger age of CPVT onset. However, the numerically higher rate of life-threatening events during follow-up in those with AT was not statistically significant. Current available treatments appear ineffective for CPVT-related AT, which should be recognized as an important feature of the disease.