The effects of the ablation of atrial flutter in patients with and without a clinical history of paroxysmal atrial fibrillation

BACKGROUND: Although the safety and effectiveness of radiofrequency (RF) transcatheter ablation in patients with atrial flutter (AFL) is well established, little attention is paid to previous history of associated paroxysmal atrial fibrillation (AF) and the recurrence of AFL after RF ablation. In addition, it is not known whether the elimination of AFL can modify the natural history of AF in patients who experience both of these arrhythmias. Accordingly, the aim of this study was to evaluate the effect of RF ablation of AFL in patients with or without a previous history of AF in terms of the incidence of both arrhythmias in the follow-up. METHODS: RF ablation of the atrial isthmus between tricuspid ring, coronary sinus os and inferior vena cava was performed in 27 patients (23 males, 4 females; mean age 61 +/- 9 years) according to the technique described by Cosio. Based on ECG pattern, twenty patients exhibited common or type 1 AFL (negative F waves in the inferior leads with a sawtooth morphology), while seven patients had both common and uncommon AFL (various surface F wave morphologies, generally positive F waves in the inferior leads). A history of association between AFL and paroxysmal AF was documented in 48% of patients, but AFL was the major arrhythmia. After ablation, the patients were followed up and the clinically documented occurrence of arrhythmias was determined. RESULTS: Based on clinical history before ablation, we compared patients with an association between AFL and AF (Gr AFL + AF; n = 13) vs patients with only AFL (Gr AFL; n = 14). The characteristics of the two groups were similar regarding age, sex, duration of symptom, structural heart disease, left atrial size, P-wave duration, AFL interruption during RF procedure, antiarrhythmic treatment before and after RF procedure, and duration of follow-up. During a follow-up of 12 +/- 6 months, AFL recurred in 10 patients (37%), 4 from Gr AFL + AF, and 6 from Gr AFL (p = NS). Episodes of paroxysmal AF occurred in 6 patients (22%), 5 from Gr AFL + AF and 1 from Gr AFL (p < 0.05). In Gr AFL + AF, the incidence of AF after ablation was significantly lower (1.8 +/- 0.6 vs. 0.7 +/- 1 episodes/year; p < 0.02). Characteristics of patients with or without AFL recurrence in the follow-up were similar. The percentage of patients with the occurrence of AFL or AF, associated or unassociated in the follow-up, was 55%. CONCLUSIONS: A history of paroxysmal AF before RF ablation of AFL is not predictive of long-term success or failure of the procedure when considering the recurrence of AFL alone. Nevertheless, the general results are disappointing because the majority of patients have arrhythmias, AFL or AF, associated or unassociated in the follow-up. A clinical history of AF before ablation is correlated with a higher incidence of AF in the follow-up. In any event, the incidence of AF episodes is lower in the follow-up, indicating a possible beneficial effect of AFL ablation on AF mechanisms.