Impact of obesity and epicardial fat on early left atrial dysfunction assessed by cardiac MRI strain analysis

Abstract

Background: Diastolic dysfunction is a major cause of morbidity in obese individuals. We aimed to assess the ability of magnetic resonance imaging (MRI) derived left atrial (LA) strain to detect early diastolic dysfunction in individuals with obesity and type 2 diabetes, and to explore the association between cardiac adipose tissue and LA function.

Methods: Twenty patients with obesity and T2D (55 ± 8 years) and nineteen healthy controls (48 ± 13 years) were imaged using cine steady state free precession and 2-point Dixon cardiovascular magnetic resonance. LA function was quantified using a feature tracking technique with definition of phasic longitudinal strain and strain rates, as well as radial motion fraction and radial velocities.

Results: Systolic left ventricular size and function were similar between the obesity and type 2 diabetes and control groups by MRI. All patients except four had normal diastolic assessment by echocardiography. In contrast, measures of LA function using magnetic resonance feature tracking were uniformly altered in the obesity and type 2 diabetes group only. Although there was no significant difference in intra-myocardial fat fraction, Dixon 3D epicardial fat volume(EFV) was significantly elevated in the obesity and type 2 diabetes versus control group (135 ± 31 vs. 90 ± 30 mL/m², p < 0.001). There were significant correlations between LA functional indices and both BMI and EFV (p ≤ 0.007).

Conclusions: LA MRI-strain may be a sensitive tool for the detection of early diastolic dysfunction in individuals with obesity and type 2 diabetes and correlated with BMI and epicardial fat supporting a possible association between adiposity and LA strain. Trials Registration Australian New Zealand Clinical Trials Registry No. ACTRN12613001069741.

Keywords: Cardiac dysfunction; Diastolic dysfunction; Fat distribution; Magnetic resonance studies; Obesity and type 2.

Fig. 1

Illustration of the methodology for LA function analysis. a, b Left atrial contours from a 4-chamber view and longitudinal strain and strain rate related curves of a subject from the Obese-Type 2 diabetes (ObT2D) group. R_o example of a radius used for the computation of the radial motion fraction. Decomposition of the radial motion fraction into MV centric (cMr, towards the mitral valve center) and MV corrected perpendicular (pMr, MV corrected perpendicular radial motion fraction) components. c, d Sl _R reservoir longitudinal strain, Sl _C conduit longitudinal strain and Sl _A La contraction longitudinal strain, SRL _S′ reservoir longitudinal strain rate, SRl _E′ conduit longitudinal strain rate and SRl _A′ LA contraction longitudinal strain rate

Fig. 2

2D intra-myocardial fat fraction (a), and 3D Dixon adipose tissue quantification (b), fat (a) images from DIXON sequence. K-means segmentation of the heart and detection of the epicardial fat (a, b)

Fig. 3

Correlations between BSA and LA functional indices in the control and ObT2D groups (a). Vr_E′/Vr_A′ related to BMI (b) and indexed adipose tissue volume (c). Correlations between LA functional indices and 3D Dixon cardiac fat fraction: longitudinal strain rates and radial relative velocities ratios (d), and radial motion fraction (e) and with radial motion fraction ratio (f)