Thromboembolic risk of patients referred for radiofrequency catheter ablation of typical atrial flutter without prior appropriate anticoagulation therapy.

BACKGROUND: Radiofrequency catheter ablation of isthmus dependent atrial flutter is considered the therapy of choice. There is, however, controversy with regard to the thrombogenicity of atrial flutter in comparison with atrial fibrillation.
METHODS: Consecutive patients scheduled for catheter ablation of documented typical atrial flutter receiving insufficient (INR < 2.0) or no anticoagulation during the three weeks preceding the procedure underwent multiplane transesophageal echocardiography (TEE). Patients with exclusive documentation of atrial flutter were classified as group I, whereas patients with additional documentation of atrial fibrillation were classified as group II.
RESULTS: The study included 201 patients, 62 of whom were not on therapeutic anticoagulation (mean age 64 +/- 9 years, 87% men). In 10 of these 62 patients (16%), TEE detected a left atrial (LA) appendage thrombus in 4, or dense spontaneous echo contrast (SEC) in 6 patients. Comparison of patients with versus without SEC or thrombus, revealed a higher incidence of valvular heart disease (60% vs 26%, P = 0.05), but no differences with respect to age, gender, LA diameter, left ventricular end-diastolic diameter, or left ventricular ejection fraction. The incidence of positive TEE findings in group I was 1 in of 36 versus 9 of 26 in group II (3% vs 35%, P < 0.001), and the relative risk for thromboembolism in group II versus group I was 12.5 (95% CI: 3-55, P < 0.001).
CONCLUSION: There is a significant risk for thromboembolism in patients referred for ablation of typical atrial flutter who have not been appropriately anticoagulated.