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2 Background- The aim of the study was to investigate whether the type of arrhythmia recurrence after ablation of persistent atrial fibrillation (AF) has an impact on the maintenance of sinus rhythm after the repeat ablation procedure. Methods and Results- Included were 78 consecutive patients (82 % males, mean age: 61±10 years, mean left atrial diameter: 47±4 mm) with persistent AF who underwent 1 repeat ablation. The initial ablation procedure had consisted of pulmonary vein isolation with additional substrate modification (ablation of complex fractionated atrial electrograms n = 63 or linear lesions n=15). Patients presented for reablation either with persistent atrial tachycardia (AT; Group 1; n=36), persistent AF (Group 2; n=37) or paroxysmal AF (Group 3; n=5). The primary endpoint was freedom from any arrhythmia off antiarrhythmic drugs (AAD) 6 and 9 months after the reablation procedure. Estimated proportions of patients reaching the primary endpoint were 59 % for Group1, 28