Association of epicardial fat tissue combined with left ventricular strain with left ventricular fibrosis in obese patients: a cardiac magnetic resonance study

Background: Obesity is an established independent risk factor for cardiovascular disease, and myocardial fibrosis represents a key pathological mechanism underlying obesity-related cardiac dysfunction. The early identification of fibrotic remodeling is therefore clinically important. Epicardial adipose tissue (EAT) exerts local paracrine and mechanical effects on the myocardium, and left ventricular (LV) strain derived from cardiac magnetic resonance (CMR) feature tracking enables sensitive detection of subclinical myocardial dysfunction. However, the association between EAT, LV strain, and LV fibrosis in obese patients remains unclear. This study aimed to investigate the association of EAT combined with LV strain with LV fibrosis in obese patients using CMR. Methods: A total of 80 obese patients were prospectively enrolled and divided into late gadolinium enhancement (LGE)(+) and LGE(-) groups based on the presence of myocardial fibrosis detected by CMR. They were matched with 80 healthy controls with normal body mass index (BMI). All participants underwent CMR non-contrast and contrast-enhanced scans to measure EAT volume, EAT thickness, and LV/left atrial (LA) function indices, including conventional cardiac function parameters and myocardial strain parameters. Spearman correlation analysis was used to assess relationships between EAT and LV/LA strain parameters. Univariate and multivariate logistic regression were performed to explore associations between EAT, LV strain, and LV fibrosis. Receiver operating characteristic (ROC) curves were used to evaluate the discriminative ability of combined EAT and LV strain for fibrosis. Results: Overall circumferential, radial, and longitudinal strains progressively decreased across the control, LGE(-), and LGE(+) groups (all P<0.05). EAT thickness and volume in the left atrioventricular groove (LAVG) and inferior interventricular groove (IIVG) were significantly higher in the LGE(+) group than they were in the LGE(-) group and control group (all P<0.05). LAVG thickness and EAT volume showed negative correlations with LA reservoir strain, conduit strain, and radial strain (r=-0.34 to -0.26, all P<0.05), and positive correlations with longitudinal and circumferential strains (r=0.18 to 0.36, all P<0.05). Multivariate logistic regression identified EAT volume [odds ratio (OR) =1.065; 95% confidence interval (CI): 1.028-1.103, P<0.001], LAVG thickness (OR =1.386; 95% CI: 1.064-1.805; P=0.016), and longitudinal strain (OR =1.322; 95% CI: 1.062-1.646; P=0.012) as independent predictors of LV fibrosis. The combined model yielded an area under the curve (AUC) of 0.943 (95% CI: 0.874-0.985). Conclusions: CMR enables precise assessment of EAT and LV strain in obese patients. LAVG thickness, EAT volume, and longitudinal strain were independently associated with LV fibrosis and may provide useful imaging information, but external validation is required before clinical application.