Sudden manifestation of sinus arrest nine months after catheter ablation treatment for persistent atrial fibrillation.

A 39-year-old man with a seemingly non-remodeled, small heart suffered persistent atrial fibrillation (AF). Extensive isolation of the pulmonary vein, superior vena cava, and posterior left atrium, in conjunction with right atrium focal ablation, was performed to ablate multiple AF foci during two catheter ablation sessions. Sinus arrest occurred suddenly during follow-up, despite the absence of recurrent AF, ultimately necessitating pacemaker implantation. This case underscores the necessity of careful follow-up after catheter ablation, highlighting the risk of sudden, severe sinus node dysfunction, even in young AF patients with small hearts.