Extended distribution of prolonged and fractionated right atrial electrograms predicts development of chronic atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation.

Introduction: This study evaluates whether electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation (PAF) predict the transition to chronic atrial fibrillation (CAF).

Methods And Results: Ninety-six patients with idiopathic PAF underwent electrophysiologic study and were followed up. During electrophysiologic study, endocardial mapping was performed at 12 sites in the right atrium (four aspects of the high, middle, and low right atrium). During follow-up of 60 to 130 months, conversion from PAF to CAF was observed in 17 patients (CAF group). The remaining 79 patients remained in sinus rhythm (PAF group). Although a high frequency of abnormal atrial electrograms was observed in the high right atrium in both groups, the frequency of those recorded from the middle right atrium was significantly higher in the CAF group than in the PAF group (70.6% vs 13.9%, P < 0.0005). Kaplan-Meier analysis showed that >50% of the patients with abnormal atrial electrograms in the middle right atrium developed CAF after 10 years, whereas only 7% of patients without those developed CAF (P < 0.0001).

Conclusion: Our data suggest that extended distribution of abnormal atrial electrograms from the high to middle right atrium is predictive of the development of CAF in patients with idiopathic PAF.