Prevalence of left atrial thrombus in patients with atrial flutter in comparison to atrial fibrillation

Abstract

Background: Atrial flutter (AFL) and atrial fibrillation (AF) are believed to carry the same risk of systemic thromboembolism. However, there is a paucity of data concerning such risk in patients with AFL in comparison to AF.

Objective: The aim of the study was to evaluate the prevalence of left atrial thrombus (LAT) on transesophageal echocardiography in patients with AFL in comparison to AF according to anticoagulation status.

Methods: The study is the subanalysis of a multicenter, prospective Left Atrial Thrombus on Transesophageal Echocardiography (LATTEE) registry, which enrolled AF and AFL patients referred for ablation or electrical cardioversion regardless of oral anticoagulation (OAC) use. All patients underwent preprocedural transesophageal echocardiography to assess the primary end point of LAT presence.

Results: A total of 3109 patients (AF, n = 2577; AFL, n = 532) were included in the study. Therapeutic OAC, defined as anticoagulation lasting at least 3 weeks, was used by 89.8% of patients in the AF subgroup and 82.5% in the AFL subgroup (P < .001). LAT was present in 8.3% of patients with AF and 6.8% with AFL, regardless of therapeutic OAC use (P = .235). In patients receiving therapeutic OAC, LAT was present in 7.6% in the AF subgroup and 5.7% in the AFL subgroup (P = .167); in patients without therapeutic OAC, LAT was present in 14.9% in the AF subgroup and 11.8% in the AFL subgroup (P = .459).

Conclusion: The risk of thrombus formation in AFL seems to be similar to that in AF, supporting similar recommendations concerning OAC use.

Keywords: Atrial fibrillation; Atrial flutter; Left atrial thrombus; Oral anticoagulation; Transesophageal echocardiography.