The anatomical basis of pulmonary vein reconnection after ablation for atrial fibrillation: wounds that never felt a scar?

Atrial fibrillation (AF), the most common cardiac arrhythmia, is a major cause of strokes, hospitalizations, and mortality in the United States. The toll of AF is expected to worsen in coming decades as the number of elderly Americans increases (1). This harsh demographic reality has provided an impetus to seek new strategies to prevent, control, and eliminate the arrhythmia. About a decade ago, it was discovered that AF is frequently triggered by ectopy or bursts of tachycardia that originate in muscle bundles that extend from the atrium to the pulmonary veins (PVs) (2) and that electrical pulmonary vein isolation (PVI) by transcatheter ablation can maintain sinus rhythm. The past decade has witnessed great enthusiasm for PVI. With current techniques, 50% to 60% of patients remain in sinus rhythm 1 year after a single procedure (3), but the remainder show early or late recurrence of AF (4).