CONGRESS ABSTRACT

Background: Juvenile-onset lone atrial fibrillation (LAF) may be the initial manifestation of an othrewise concealed channelopathy or cardiomyopathy (CMP). Clinical characteristics, genetic background and proper management are still largely unknown.
Purpose: describe the clinical and genetic characteristics of patients with juvenile-onset LAF.
Methods: We enrolled patients referred to our center for ablation between 1/2018 and 11/2023 with a first diagnosis of LAF below 60 years, absence of CMP, ischemic, valvular, congenital heart disease, and no overt channelopathy. A concealed Brugada syndrome was systematically excluded. Genetic testing was performed using Next Genome Sequencing and a dedicated gene panel.
Results: 89 patients were included (84% male, LAF onset 43  8 years, BMI 25  7 kg/m2): 32% had a first-degree family history of AF (including 15% below 60 years), 18% of sudden death, 8% of cardiac conduction disorders and 2% of CMP. Arterial hypertension was present in 24%, smoking in 47% and obstructive sleep apnea in 4%; 20% were competitive athletes. Most patients (89%) presented with symptomatic paroxysmal AF (palpitations); LVEF was 615% and LAVI 3514 ml/m2. Median follow-up time after the first AF was 6 years (IQR 4-10). Most patients (81, 91%) underwent ≥1 ablation after failed anti-arrhythmic drug (AAD) therapy (mostly IC). The first procedure (73% radiofrequency, 27% cryoablation) included pulmonary veins isolation (PVI) in all and additional lesions in 5%; the second (n=18, 22% of the ablation group) included PV re-isolation in all and additional lesions in 17%; the third (n=8, 10% of the ablation group) included PV re-isolation in 25% and additional lesions in 75%. The remaining 8 patients were treated with AAD only (mostly IC). By the last follow-up, 7% of patients in the ablation group and 25% in the AAD group had documented recurrences (even though 50% of those who received ablation were still on AAD). Among the 35 patients subjected to genetic investigation, 10 have available results: 30% tested positive for C4-C5 variants (2 for KCNQ1, 1 for TTN), 50% for C3 variants (RYR2, ABCC9, LMNA, KCNH2 and RMB20) and 20% were negative.
Conclusions: In the present cohort of patients with juvenile-onset LAF, a positive family history was found in almost one third of patients. Despite prompt diagnosis and treatment, recurrences rate is not trivial. The yield of genetic test so far is high, supporting its use in this population.