Typical atrial flutter as a risk factor for the development of atrial fibrillation in patients without otherwise demonstrable atrial tachyarrhythmias

OBJECTIVE: To investigate the incidence of atrial fibrillation after successful radiofrequency ablation for typical atrial flutter (AFL) and to compare its incidence with that of a reference population from the Framingham Heart Study to determine whether atrial flutter is an independent predictor for development of atrial fibrillation. PATIENTS AND METHODS: Medical records of 234 patients who underwent radiofrequency ablation for AFL between January 1, 2002, and June 30, 2006, were reviewed. Patients were excluded if they had a history of atrial fibrillation or sustained atrial arrhythmia other than AFL or if they had atrial tachyarrhythmias other than AFL that could be induced during electrophysiology study (133 total patients excluded). The remaining 101 patients who underwent successful radiofrequency ablation for AFL were monitored for new-onset atrial fibrillation. RESULTS: During the mean ± SD follow-up period of 574±315 days, atrial fibrillation developed in 13 (12.9%) of 101 patients. Atrial fibrillation developed in 12 of these patients within 6 months of ablation. The cumulative event-free rates (95% confidence intervals) were 97% (94%-100%) at 1 month, 91% (87%-97%) at 3 months, and 86% (81%-94%) at 6 months. Compared with the general population, patients aged 50 to 79 years who had ablation had a significantly higher incidence of atrial fibrillation (50-59 years, P=.01; 60-69 years, P=.001; 70-79 years, P=.007). CONCLUSION: Our finding of atrial fibrillation in 12.9% of patients whose atrial flutter was successfully eradicated suggests that patients with atrial flutter are at increased risk of developing atrial fibrillation, especially within the first 6 months after ablation.