Epicardial fat and left atrial appendage thrombosis in patients with persistent atrial fibrillation

BACKGROUND: Excessive deposition of the epicardial adipose tissue (EAT) plays a role in the development of a number of cardiovascular diseases, including ischemic stroke. As more than half of strokes in patients with atrial fibrillation (AF) are cardioembolic, and the source of thromboembolic complications is the left atrial appendage (LAA), it can be assumed that excess EAT contributes to the development of LAA thrombus. The literature does not present the results of a study of the relationship between the amount of EAT and LAA thrombus in patients with AF, which makes it relevant to study this issue.

AIM: to study the effect of EAТ on LAA thrombosis and the emptying flow velocity from the LAA in patients with persistent AF.

MATERIALS AND METHODS: The patients with persistent AF underwent transesophageal and transthoracic echocardiography before the planned cardioversion. The transesophageal echocardiography measured the emptying flow velocity from the LAA, and the thickness of the interatrial septum and the left lateral ridge, the average value of which was used to estimate the amount of left atrial EAT. The thickness of the anterior wall of the right ventricular EAT was measured by transthoracic echocardiography.

RESULTS: The LAA thrombus was detected in 42 (8.6%) patients of 486 patients with persistent AF (age 64.0 [59.0; 70.0] years, men 58.0%). Patients with thrombus had greater thickness of the left atrial EAT (9.30 [9.05; 9.55] vs. 7.70 [7.03; 8.28] mm, p<0.001) and of the right ventricular EAT (8.05 [7, 90; 8.90] versus 7.80 [7.20; 8.40] mm, p = 0.001), but the emptying flow velocity from the LAA is lower (20.0 [14.0; 26.0] versus 32.0 [26.0; 39.0] cm/s, p<0.001). Area under the receiver operator characteristic curve for the thickness of the left atrial EAT, as a predictor of the LAA thrombosis, was significantly larger than for the thickness of the right ventricular EAT: 0.947 (0.923–0.965) versus 0.661 (0.617–0.703), p<0.001. The thickness of the left atrial EAT more than 8.6 mm increases the chances of LAA thrombosis by 70.1 (24.1–204.2) times. Analysis of multiple linear regression did not reveal an independent effect of the thickness of the left atrial EAT (b = -0.0951±0.6163, p = 0.877) and of the right ventricular EAT (b = 0.6764±0.4383, p = 0.124) on the emptying flow velocity from the LAA.

CONCLUSION: The increased of the thickness of EAT increases the chances of developing LAA thrombosis in patients with persistent AF, but does not affect on the emptying flow velocity from the LAA.

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