Epicardial adipose tissue and subclinical incident atrial fibrillation as detected by continuous monitoring: a cardiac magnetic resonance imaging study

Abstract

Epicardial adipose tissue (EAT) has endocrine and paracrine functions and has been associated with metabolic and cardiovascular disease. This study aimed to investigate the association between EAT, determined by cardiac magnetic resonance imaging (CMR), and incident atrial fibrillation (AF) following long-term continuous heart rhythm monitoring by implantable loop recorder (ILR). This study is a sub-study of the LOOP study. In total, 203 participants without a history of AF received an ILR and underwent advanced CMR. All participants were at least 70 years of age at inclusion and had at least one of the following conditions: hypertension, diabetes, previous stroke, or heart failure. Volumetric measurements of atrial- and ventricular EAT were derived from CMR and the time to incident AF was subsequently determined. A total of 78 participants (38%) were diagnosed with subclinical AF during a median of 40 (37-42) months of continuous monitoring. In multivariable Cox regression analyses adjusted for age, sex, and various comorbidities, we found EAT indexed to body surface area to be independently associated with the time to AF with hazard ratios (95% confidence intervals) up to 2.93 (1.36-6.34); p = 0.01 when analyzing the risk of new-onset AF episodes lasting ≥ 24 h. Atrial EAT assessed by volumetric measurements on CMR images was significantly associated with the incident AF episodes as detected by ILR.

Keywords: Atrial fibrillation; Cardiac magnetic resonance; Epicardial adipose tissue.

Fig. 1

Analyses of cardiac magnetic resonance imaging. Image A–C: To ensure sufficient dimensional orientation, a two-chamber image is used as reference. In this figure, the reference is presented in three different slices marked with yellow, red, and turquoise. Below these images, the axial cine images before and after contouring of the epicardial adipose tissue (EAT) are presented. The volumetric measurements are performed on all slices in a full image stack for all participants, where it is divided into ventricular EAT (pink) and atrial (blue)

Fig. 2

New-onset Atrial Fibrillation. This figure represents the hazard ratios (95% confidence intervals) for associations between epicardial adipose tissue (EAT) and the risk of developing new-onset AF episodes ≥ 6 min in yellow, ≥ 5.5 h in green, and ≥ 24 h in violet. The figure illustrates results from a cause-specific Cox model adjusted for age, sex, heart failure, diabetes, previous stroke, previous acute myocardial infarction, and/or coronary artery bypass graft surgery, cardiac valvular disease, and either left atrial total ejection fraction (LATEF), representing Model 2, or left atrial minimum volume (LAMIN), representing Model 3. Both EAT and LAMIN are indexed to body surface area (BSA) indicated by i