The Natural History of Lone Atrial Flutter

Background: The natural history of atrial flutter is not well defined. Objective: To report the risk for stroke, conversion to atrial fibrillation, and anticoagulation for lone atrial flutter. Design: Retrospective cohort analysis. Setting: A clinically based longitudinal study of inpatients and outpatients with atrial flutter. Patients: The authors compared the stroke rate in 59 patients with atrial flutter with rates in a sample in which age- and sex-specific ischemic cerebrovascular event rates were determined and in a sample of nonhypertensive patients with lone atrial fibrillation. The risk for developing atrial fibrillation after presenting with atrial flutter is also reported. Measurements: Electrocardiograms and clinical data were collected and reviewed for each study participant. Results: After adjustment for age and sex, patients with atrial flutter had a higher incidence of thromboembolic events than the sample control patients and patients with atrial fibrillation. Atrial fibrillation developed in 56% of patients with atrial flutter. Conclusions: Lone atrial flutter has a stroke risk at least as high as lone atrial fibrillation and carries a higher risk for subsequent development of atrial fibrillation than in the general population. Anticoagulation should be considered for all patients with atrial flutter who are older than 65 years of age.