Among 63 patients affected by symptomatic drug refractory paroxysmal atrial fibrillation who had undergone atrioventricular junction ablation and dual-chamber pacemaker implantation, the actuarial estimate of progression of permanent atrial fibrillation was 22%, 40%, and 56% respectively, 1, 2, and 3 years after ablation. A stratification of the risk of development of permanent atrial fibrillation was obtained on the basis of several clinical variables.