One Shot, One Rhythm: Termination of Refractory Persistent Atrial Fibrillation in a Young Patient via Single Pulmonary Vein Application: A Case Report

<b>Background/Objectives:</b> Atrial fibrillation (AF) is the most common sustained arrhythmia, with catheter ablation outcomes differing significantly between paroxysmal and persistent forms. While pulmo-nary vein isolation (PVI) remains the cornerstone of ablation, persistent AF is often associ-ated with atrial remodeling and non-pulmonary vein triggers, reducing procedural success rates and necessitating repeat interventions. However, in selected patients with minimal atrial substrate, a single PVI may achieve durable rhythm control. This case report illus-trates such a scenario in a young patient with persistent AF and tachyarrhythmia-induced cardiomyopathy (TIC). <b>Methods:</b> A 42-year-old previously healthy male presented with newly diagnosed persistent AF complicated by TIC and heart fail-ure (left ventricular ejection fraction [LVEF] 25%). Despite rate control, anticoagulation, guideline-directed heart failure therapy, amiodarone pretreatment, and two failed electrical cardioversions, the patient remained symptomatic. Elec-troanatomic mapping was performed to assess atrial substrate prior to radiofrequency ablation. <b>Results:</b> Mapping revealed no extensive low-voltage zones, indicating absence of significant atrial fibrosis. During ablation, si-nus rhythm was restored spontaneously with a single application targeting the infero-posterior aspect of the right infe-rior pulmonary vein. No additional arrhythmogenic substrate was identified. The patient maintained sinus rhythm throughout 14 months of follow-up, with marked clinical improvement, normalization of LVEF (55%), regression of atrial and ventricular enlargement, and resolution of heart failure symptoms. Quality of life, assessed by the ASTA question-naire, improved from 24 to 0 points. <b>Conclusions:</b> This case highlights that even in therapy-resistant persistent AF with severe structural and functional cardiac impairment, arrhythmia may be driven by discrete pulmonary vein-dependent mechanisms. Careful patient selection, particu-larly in younger individuals without advanced atrial remodeling, can identify those in whom PVI alone achieves durable rhythm control and reverse cardiac remodeling.