Atrioventricular block (AVB) is a degenerative disease and more commonly encountered in elderly patients, but unusual and often of unknown etiology in young patients. This study aimed to investigate the potential contributions of genetic variations to AVB of unknown reasons in young patients.

Genetic variants were identified in 20 (20/41, 48.8%) patients, 11 (11/20, 55%) of whom had LMNA variants including 3 pathogenic (c.961C>T, c.936+1G>T and c.646C>T), 4 likely pathogenic (c.1489-1G>C, c.265C>A, c.1609-2A>G and c.1129C>T) and 3 of uncertain significance (c.1158-3C>G, c.776A>G and c.674G>T). Compared to those without LMNA variants, patients with LMNA variants demonstrated a later age at onset of AVB (41.45 ± 9.89 years vs. 32.93 ± 12.07 years, P = 0.043), had more prevalent family history of cardiac events (81.8% vs. 16.7%, P < 0.000), suffered more frequently atrial (81.8% vs. 10.0%, P < 0.000) and ventricular (72.7% vs. 10.0%, P < 0.000) arrhythmias, and were more significantly associated with enlargement of left atrium (39.91 ± 7.83 mm vs. 34.30 ± 7.54 mm, P = 0.043) and left ventricle (53.27 ± 8.53 mm vs. 47.77 ± 6.66 mm, P = 0.036).