Abstract
BACKGROUND: Hypertension (HTN) and obesity are major interrelated public health concerns that jointly contribute to cardiac dysfunction. This study aimed to utilize cardiac magnetic resonance feature-tracking (CMR-FT) to assess left atrial (LA) strain characteristics in HTN patients with varying degrees of obesity and to explore key influencing factors including epicardial adipose tissue (EAT). METHODS: In this cross-sectional study of 129 essential hypertension (EH) patients [categorized by body mass index (BMI) into normal, overweight, and obese groups], CMR-FT was performed to assess LA and ventricular structure and function including LA strain [total strain (ε(s)), passive strain (ε(e)), active strain (ε(a))] and LA strain rates [peak positive strain rate (SRs), peak early negative strain rate (SRe), peak late negative strain rate (SRa)]. EAT volume was also calculated through Cine series. The Kruskal-Wallis H test was used to compare differences in clinical data and CMR parameters among groups. Spearman correlation and multivariable regression analysis were performed to identify independent determinants of the LA strain parameters. RESULTS: Although LA volume indices and ejection fractions did not differ significantly, the obese group showed impaired strain rates (SRs: 1.1 vs. 1.3 vs. 1.5 s-1, P=0.001; SRe: -1.3 vs. -1.6 vs. -1.7 s-1, P=0.044; SRa: -1.2 vs. -1.4 vs. -1.4 s-1, P=0.044). Multivariable analysis identified LA passive and active emptying fractions as the primary determinants of passive and active strain, respectively. EAT was independently associated with impaired reservoir function (SRs: β=-0.189, P=0.015) and conduit function (SRe: β=0.204, P=0.005), particularly in overweight cases. CONCLUSIONS: CMR-FT reveals early LA dysfunction in patients with HTN and obesity, with detectable strain rate impairment before volumetric changes. Although LA passive emptying fraction and LA active emptying fraction were the principal determinants of LA deformation, EAT volume may provide incremental explanatory value beyond BMI for obesity-related LA dysfunction.