Analysis of left atrial thrombus in atrial flutter and atrial fibrillation

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

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

The study is the sub-analysis of 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 pre-procedural TEE to assess the primary endpoint of the LAT presence.

A total of 3109 patients (AF n=2481;AFL n=532;AF+AFL n=96) were included in the study. Therapeutic OAC, defined as anticoagulation lasting at least three weeks, was used by 89.8% of patients in the AF subgroup, 82.5% in the AFL subgroup, and 92.7% in the AF + AFL subgroup (p<0.001). LAT was present in 8.5% of patients with AF, 6.8% with AFL, and 4.2% with AF + AFL regardless of chronic therapeutic OAC use (p=0.156, Figure). In patients on therapeutic OAC, LAT was present in 7.7% in AF group, 5.7% in AFL subgroup, and 3.4% in AF+AFL subgroup (p=0.115), while in patients without therapeutic OAC in 15.0% in AF subgroup, 11.8% in AFL subgroup and 14.3% in AF+AFL subgroup (p=0.759).

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