The Natural History of Lone Atrial Flutter

Abstract & Commentary

Synopsis: Patients with lone atrial flutter have an increased risk for thromboembolic events and use of anticoagulation is urged for all patients with atrial flutter who are older than 65.

Source: Halligan SC, et al. Ann Int Med. 2004;140:265-268.

In this paper, Halligan and colleagues identified and determined the natural history of patients with lone atrial flutter. Halligan et al used the medical database maintained on all residents of Olmsted County, Minn, to identify patients with atrial flutter. Five hundred and sixty-seven patients were identified. Halligan et al then excluded patients with any form of cardiac disease with the exception of controlled hypertension. Patients with atrial flutter that occurred only as a consequence of an acute illness were also excluded. These patients with "lone atrial flutter" were then compared to 2 control groups: the general population of Rochester, Minn, and a second control group consisting of Olmsted County patients with no history of hypertension who received a diagnosis of lone atrial fibrillation. Survival and stroke or transient ischemic attack rates were calculated for the 3 patient cohorts. A proportional hazards model technique was used to identify variables associated with the development of atrial fibrillation and stroke or transient ischemic attack in the patients with lone atrial flutter.

Fifty-nine patients were identified who had lone atrial flutter during this 30-year period. Of these, 75% later developed recurrent episodes or persistent flutter. The average age at diagnosis was 70, with a range of 40-97 years. Of these 59 patients, 20 had controlled hypertension. Eleven had diabetes mellitus, 3 had had prior transient ischemic attacks, and 1 had a history of an ischemic stroke. Medical therapy in these patients consisted of digitalis (61%), beta-blockers (17%), calcium channel blockers (31%), and antiarrhythmic drugs (24%). Atrial flutter ablation was introduced relatively late during the period covered in this study, and only 4 patients underwent atrial flutter ablation. At the time of diagnosis, 31 patients were receiving antithrombotic or antiplatelet therapy. At latest follow-up, 41 patients were being treated with antithrombotic or antiplatelet agents. Atrial fibrillation developed in 33 of 59 patients, a mean of 5.5 ± 6 years after the initial diagnosis of atrial flutter. Significant age- and sex-adjusted predictors for developing atrial fibrillation were diabetes, hypertension, and recurrent atrial flutter. Nineteen of 59 patients (40%) experienced at least 1 cerebrovascular ischemic event during follow-up. The mean age at the time of these events was 80 ± 10 years. The mean time from atrial flutter diagnosis to cerebrovascular event was 4.3 ± 3.9 years. Six of these 19 patients had previously developed atrial fibrillation. An actuarial analysis indicated a 5-year stroke risk of 23% and a 10-year stroke risk of 35%. Patients with atrial flutter had a higher incidence of ischemic stroke or transient ischemic attack than patients with atrial fibrillation. This was true even among the atrial flutter patients without hypertension. Halligan et al concluded that patients with lone atrial flutter have an increased risk for thromboembolic events and urge use of anticoagulation for all patients older than 65 with atrial flutter.

Comment by John DiMarco, MD, PhD

There are relatively few data in the literature on the management of patients with only atrial flutter. Large series have often combined patients with atrial fibrillation and atrial flutter. Although many patients, as shown in this series, have both atrial flutter and atrial fibrillation at various times during their clinical course, this is not always true. The data in this paper suggest that atrial flutter has at least the thromboembolic potential of atrial fibrillation and, therefore, guidelines for anticoagulation used for patients with atrial fibrillation should also apply to patients with atrial flutter, even in the absence of any structural heart disease.

Recently, it has been standard practice to perform ablation of the cavotricuspid isthmus early in the course of patients who present with typical atrial flutter. Recently, however, it has been shown that the recurrence rate of atrial fibrillation is high after atrial flutter ablation. It is likely that the reported recurrence rate underestimates the recurrence rate since asymptomatic episodes of atrial fibrillation may also occur. Therefore, ablation for atrial flutter should probably be regarded as a palliative, rather than a curative, procedure, especially in patients without structural heart disease.

This paper does not mention the development of other types of conduction system diseases in its cohort. This is surprising. In my experience, atrial flutter often presents in association with sinus node dysfunction. In particular, patients who present with atrial flutter and controlled ventricular rates, many of whom may be asymptomatic, often have underlying sinus node disease. The coexistence of conduction system disease and atrial flutter is another reason why ablation procedures may only be palliative in this condition.

Dr. DiMarco, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville, is on the Editorial Board of Clinical Cardiology Alert.