First-Line Treatment for Atrial Flutter in the Elderly: Ablation

Abstract & Commentary

By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville. Dr. DiMarco is a consultant for Novartis, and does research for Medtronic and Guidant.

Synopsis: RFA should be considered a first-line therapy even after the first episode of symptomatic AFL.

Source: Da Costa A, et al. Results From the Loire-Ardeche-Drome-Isere-Puy-de-Dome (LADIP) Trial on Atrial Flutter, a Multicentric Prospective Randomized Study Comparing Amiodarone and Radiofrequency Ablation After the First Episode of Symptomatic Atrial Flutter. Circulation. 2006;114:1676-1681.

Da Costa and colleagues report a multicenter, randomized trial comparing amiodarone and radiofrequency ablation in elderly patients with atrial flutter. The study was named the LADIP Trial after the first letters of the cities of the investigators. Patients older than age 70 were considered eligible for the trial if they presented with a first episode of atrial flutter that appeared to be consistent with classic counterclockwise right atrial macroreentry. This was confirmed in most patients by electrophysiologic study or by entrainment with right atrial pacing. They could not have been previously treated with antiarrhythmic drugs. Patients were randomly assigned to either radiofrequency ablation or amiodarone as initial therapy. The electrophysiologic studies and catheter ablations were performed using standard approaches. Either an 8 mm tip electrode catheter or an irrigated 5 mm tip thermocouple catheter were used for the ablations. The procedural end point was bidirectional isthmus block. Patients in the amiodarone group were assigned to electrical cardioversion. Initially, this was attempted with a right atrial catheter that was used to confirm right cavotricuspid isthmus entrainment. If rapid pacing did not restore sinus rhythm, external or internal cardioversion was applied. Patients then received amiodarone at a dose of 400 mg for 4 weeks starting 7 days before the atrial pacing. After that, amiodarone was continued at a dose of 200 mg daily.

During follow-up, patients were seen at periodic intervals. Arrhythmia monitoring was performed using a combination of history, 12 lead electrocardiograms, and Holter monitoring. The Holter monitoring was performed using an event recorder that performed a continuous ECG analysis combined with automatic storage of abnormal events detected in a 20-minute solid state memory. Manual activation of the Holter storage was also possible. The primary end point was time to occurrence of atrial flutter confirmed by ECG. Time to first occurrence of atrial fibrillation was a secondary end point. Episodes lasting longer than 10 minutes were considered clinically significant but episodes lasting from one minute to 10 minutes were quantified. Patients in the amiodarone group who developed recurrent atrial flutter went on to receive radiofrequency ablation.

One hundred and four patients were entered into the trial with 52 entered into both the radiofrequency ablation and the amiodarone groups. In the radiofrequency ablation group, bidirectional block was achieved in 100% of patients with a mean radiofrequency application time of 12.8 + 13 minutes. There were no procedure-related complications. In the amiodarone group, 12 patients converted to sinus rhythm during the initial 7 days of amiodarone, 17 were converted by intraatrial pacing and 22 by internal or external direct current cardioversion. After a mean follow-up of 13 ± 6 months, atrial flutter recurred in 2 of 52 (3.8%) radiofrequency ablation patients, in contrast to 15 of 51 (29.5%) amiodarone treated patients. Significant symptomatic or asymptomatic atrial fibrillation of greater than 10-minute duration occurred in 25% of the group 1 patients and 18% of the group 2 patients. When all atrial fibrillation episodes were taken into account, including asymptomatic episodes of less than 10 minutes duration, documented by ECG, the 2 groups did not differ significantly with 29% of the radiofrequency ablation patients and 20% of the amiodarone patients having episodes. Patients who had prior episodes of atrial fibrillation were more likely to have recurrent atrial fibrillation after the first episode of atrial flutter.

There were 6 deaths in the radiofrequency ablation group and 8 deaths in the amiodarone treated group. Most deaths were noncardiovascular in origin and not apparently related to the atrial arrhythmia. Five other major clinical events occurred in the amiodarone treated group: hypothyroidism in 2, hyperthyroidism in one, and symptomatic sinus node dysfunction in 2.

The authors conclude that in patients 70 years or older, radiofrequency ablation should be considered to be the preferred therapy for classic atrial flutter. Although the risk of subsequent atrial fibrillation remains high, the procedure can be performed with a low risk of complications and the strategy does not subject patients to the adverse effects of long-term drug therapy.

Commentary

Atrial flutter is a particularly bothersome arrhythmia. Unlike atrial fibrillation during which concealed conduction of the AV node allows rate control to be achieved in most patients, rate control in atrial flutter is often difficult and most patients usually must be cardioverted out of atrial flutter to control their symptoms. Over the last decade, electrophysiologists have learned that the common type of atrial flutter involves a counterclockwise macroreentrant circuit in the right atrium. This circuit often passes through a critical isthmus between the inferior vena cava and the tricuspid annulus. Placing an ablation line through this area terminates atrial flutter and prevents its recurrence. In experienced hands, the procedure is very safe and highly successful. Recurrence rates which were high when the procedure was first introduced have fallen dramatically with the introduction of either cooled-tip or large tip radiofrequency ablation catheters. In the study here, the LADIP investigators confirmed that radiofrequency ablation is an effective initial therapy for patients with atrial flutter. The major disappointment with the procedure involves the relatively high incidence of atrial fibrillation during follow-up. The pathologic bases for atrial fibrillation and atrial flutter are similar. Therefore, it is not surprising given the patient cohort here included only those over age 70 that the incidence of atrial fibrillation during follow-up was similar in the 2 groups. However, the observations that the risk of any arrhythmia recurrence is no higher and that the complications associated with the radiofrequency ablation procedure are lower than those associated with chronic antiarrhythmic therapy argue that the invasive approach should be the preferred strategy for patients who present with typical atrial flutter.