Radiofrequency ablation vs medical therapy after a first episode of symptomatic atrial flutter

Stephen C. Vlay, MD is professor of medicine at State University of New York, Stony Brook, New York.

Cardiology Review® Online, June 2007, Volume 24, Issue 6

Atrial flutter is an arrhythmia that occurs less commonly than atrial fibrillation and is often resistant to rate control and termination.

Atrial flutter is an arrhythmia that occurs less commonly than atrial fibrillation and is often resistant to rate control and termination. Electrical cardioversion, atrial overdrive pacing, or antiarrhythmic drugs often are required to terminate the arrhythmia. Medical therapy can involve beta blockers, digoxin (Lanoxin), and specific antiarrhythmic drugs. It is far easier to control the ventricular response to atrial fibrillation than to control atrial flutter. What, then, should be the approach of the clinician who encounters a patient with atrial flutter? First, what is the setting? Is the patient postoperative cardiac surgery, a common setting for this arrhythmia? If so, as inflammation decreases, so may the risk of recurrent arrhythmia. Does the patient have structural heart disease? If so, cardiac evaluation must first occur. Is it just an arrhythmia problem?

It should be remembered that atrial flutter and atrial fibrillation frequently coexist. If atrial flutter triggers atrial fibrillation, that is, one atrial arrhythmia begets another, then atrial flutter ablation may decrease the episodes of atrial fibrillation. Nevertheless, some of these patients remain at risk for and will have episodes of atrial fibrillation. Thus, this group will continue to need anticoagulation and possibly rate control.

Da Costa and colleagues

address the issue of where radiofrequency ablation should be positioned in the management of patients with atrial flutter. Atrial flutter is a rhythm more organized than atrial fibrillation and most commonly involves a counterclockwise circuit in the right atrium. The target for intervention is the inferior vena cava-tricuspid valve isthmus, usually easily accessible with just a right-sided (ie, venous) procedure in the electrophysiology laboratory, which does not have a risk of arterial thromboembolism. The site is distant enough from the A-V node to have only a minimal risk of heart block. The usual risks of electrophysiology study do apply. The creation of bidirectional block will terminate atrial flutter and prevent recurrence. In some cases, the ablation may be technically difficult.

In the study by Da Costa and colleagues, 104 elderly subjects with a first episode of atrial flutter were randomly assigned to receive treatment with amiodarone (Cordarone, Pacerone) or radiofrequency catheter ablation. After a 13-month period of follow-up, recurrent atrial flutter was seen in 29.5% of the medically treated subjects and in only 3.8% of subjects who underwent ablation. The incidence of atrial fibrillation was the same (8%) in both groups. The authors concluded that ablation was superior to amiodarone in preventing recurrence of atrial flutter.

One limitation of the study was that the number of patients was small (n = 104) and may be too small to justify a broad-ranging recommendation, such as proposing a strategy of ablation as first-line therapy. In terms of the medical therapy, amiodarone was loaded but there is no mention of the presence or absence of a beta blocker or digoxin. In fact, why not try a beta blocker alone first as prevention? Certainly, if the arrhythmia was ischemic or catecholamine related, perhaps a beta blocker might be beneficial.

Interestingly, in this study, the recurrence rate in the amiodarone group was relatively low, 29%. In other studies, the recurrence rate of atrial flutter was higher, up to 50% after a first episode and up to 93% after a second episode, as noted in the discussion. Do patients with multiple episodes of atrial flutter represent another population? However, for the subjects with only 1 episode of atrial flutter, if 71% of subjects did not have recurrence, perhaps there is still a role for medical therapy before an invasive procedure is considered. Thus, the 2003 recommendations of American College of Cardiology (ACC)/American Heart Association (AHA)/European Society of Cardiology (ESC) remain appropriate, that is, that the first well-tolerated episode of atrial flutter be classified as a IIa indication for ablation therapy.

The bottom line is that ablation may be a consideration for patients with atrial flutter, even after a single episode, but it still is an invasive procedure. If you were 78 years old and had a first episode of atrial flutter, and the chances of success with medical therapy were 71%, what would you choose? And why not start with a beta blocker or digoxin first? Certainly, is it not unreasonable to offer patients both options, medical therapy and ablation, and let them participate in the decision? Until there are more patient data to justify classifying ablation a class I indication for atrial flutter, the 2003 recommendations of the ACC/AHA/ESC seem appropriately positioned.