Clinical manifestations and outcomes of idiopathic ventricular fibrillation and early repolarization syndrome in adolescents: A multicenter cohort study

BACKGROUND Idiopathic ventricular fibrillation (IVF) and early repolarization syndrome (ERS) are rare but potentially life-threatening arrhythmias. Their clinical distinction is often challenging and prognostic factors remain unclear, particularly in adolescents. OBJECTIVE This study compared clinical outcomes and electrocardiographic characteristics of adolescents with IVF and ERS to identify disease-specific prognostic factors. METHODS Patients diagnosed with IVF or ERS between 2000 and 2022 were retrospectively reviewed from a nationwide Korean multicenter cohort of pediatric inherited arrhythmia syndrome. ECGs were systematically reanalyzed for early repolarization patterns (ERP). Life-threatening arrhythmic events (LAEs), including ventricular arrhythmias, appropriate implantable cardioverter-defibrilltor shock, and sudden cardiac arrest, were compared between the groups. RESULTS ECG reanalysis led to reclassification of 10 patients from IVF to ERS, resulting in 14 ERS and 25 IVF patients (mean age: 16.0±2.3, 92.3%, male). LAEs were more frequent in the ERS group (92.9% vs. 52.0%, P =0.025), with shorter LAE-free survival (median 7.2 vs. 51.6 months, P =0.005). In ERS, inferolateral ERP predicted poorer prognosis compared with inferior ERP (HR 9.29 [1.68–101.36], P =0.009 ), whereas coexistence of supraventricular tachycardia was a risk factor for LAEs in IVF (HR 7.24 [1.89–29.73], P =0.005). J-wave duration was longer in inferolateral ERP and in cases with pause-dependent augmentation. CONCLUSION IVF and ERS have distinct prognoses and risk factors in adolescent patients. ECG-based differentiation and identification of prognostic factors may guide individualized strategies.