Shah DC, Haissaguerre M, Jais P. Thorac Cardiovasc Surg 47 Suppl 3:352-6, 1999. While experimental and human mapping studies have documented multiple wavelet reentry as the electrophysiological mechanism maintaining atrial fibrillation, recent evidence shows that nearly all paroxysms of atrial fibrillation are initiated by trains of rapid discharges from the pulmonary veins. Radiofrequency catheter ablation targeting these initiating triggers has resulted in an overall 69% freedom from atrial fibrillation at a follow-up of 8 +/- 4 months in a population of 110 patients with paroxysmal atrial fibrillation. Six of the targeted pulmonary veins (4%) developed pulmonary vein stenosis; none requiring specific treatment. Catheter ablation of pulmonary vein foci initiating atrial fibrillation is therefore an effective curative modality for paroxysmal atrial fibrillation.