The study recruited 67 patients with systemic lupus erythematosus admitted between February 2025 and November 2025, along with 31 age- and gender-matched healthy controls. Lupus diagnosis was confirmed using the 2019 classification criteria jointly revised by the European League Against Rheumatism and the American College of Rheumatology, requiring antinuclear antibody positivity at a titer of at least 1:80 and a cumulative score of at least 10 points across clinical and immunologic domains. The team deliberately excluded patients with other autoimmune disorders, prior myocarditis or coronary artery disease, valvular or congenital heart disease, uncontrolled hypertension, severe arrhythmias, and poor-quality images — a design choice intended to isolate the relationship between the fat layer and heart function without the confounding noise of established cardiac disease.

Epicardial adipose tissue occupies a unique anatomical position. It lies between the myocardium and the visceral pericardium, with no fascial barrier separating it from the heart muscle and coronary arteries it envelops. Under healthy conditions, this fat depot is a friend to the heart: it buffers coronary torsional stress during each cardiac cycle, supplies the majority of free fatty acids that fuel myocardial ATP production, secretes anti-inflammatory and anti-fibrotic adipokines such as adiponectin, and even contributes to non-shivering thermogenesis through UCP-1. But under pathological conditions the relationship flips. The tissue becomes inflamed, hypoxic, and oxidatively stressed, releasing pro-inflammatory cytokines and lipid intermediates that damage the very muscle it once nourished. Because it communicates with the myocardium through paracrine and vasocrine signaling, its thickness on an ultrasound image may be a direct readout of the chemical environment surrounding the heart.

To measure how well the lupus patients’ hearts were actually contracting, the researchers went beyond the conventional ejection fraction. They used two-dimensional speckle tracking echocardiography, a technique that tracks the spatial motion of natural acoustic markers — speckles — within the myocardium frame by frame, quantifying the real-time deformation of heart muscle during the cardiac cycle. Using a Philips EPIQ CVx system with frame rates above 70 frames per second, the team acquired dynamic images from apical two-chamber, three-chamber, and four-chamber views and analyzed them with QLAB software, deriving apical longitudinal strain for each view and a global longitudinal strain (GLS) calculated from an 18-segment model of the left ventricle. GLS has repeatedly been shown to outperform ejection fraction in sensitivity: it detects subclinical myocardial injury even when ejection fraction looks perfectly normal, and it carries independent prognostic value.

The results were striking on both fronts. Compared with controls, the lupus patients showed significantly increased epicardial fat thickness at every measurement plane — parasternal long-axis, parasternal short-axis at the papillary muscles, parasternal four-chamber, and apical four-chamber — with mean thickness rising from 4.1 millimeters in controls to 5.0 millimeters in patients. Their left ventricular posterior wall was also significantly thicker, hinting at early structural remodeling. Meanwhile, apical two-chamber, three-chamber, and four-chamber longitudinal strain and GLS were all significantly reduced in the patient group, with GLS falling from about −20.0% in controls to −18.2% in patients. Crucially, left ventricular ejection fraction showed no significant difference between the groups — meaning the speckle-tracking technique was catching damage that the standard clinical parameter was blind to.

The team then pushed the analysis one level deeper, dividing the 18 left ventricular segments according to the coronary arteries that supply them: the left anterior descending artery, the right coronary artery, and the left circumflex artery. Strain was reduced in all three territories in the lupus patients, and the pattern was diffuse and uniform rather than confined to a single vascular bed. That distinction matters. Traditional coronary artery disease produces regional deficits that map onto specific blocked vessels; the lupus-related injury seen here spread across the entire ventricle, consistent with a mechanism that does not depend on focal plaque rupture. From a spatial standpoint, this pattern supports the hypothesis that the adjacent fat layer injures the underlying myocardium directly through paracrine signaling rather than through discrete coronary lesions.

Spearman correlation analysis confirmed the link quantitatively. Epicardial fat thickness was negatively correlated with global longitudinal strain (r = −0.39), and with strain in the right coronary (r = −0.47), left circumflex (r = −0.29), and left anterior descending (r = −0.26) territories. The strongest and most consistent correlations appeared for GLS and apical two-chamber strain. Fat thickness also correlated positively with disease duration (r = 0.41) and age (r = 0.45), and with markers of remodeling such as posterior wall and septal thickness, but showed no significant relationship with ejection fraction or with most laboratory parameters, including inflammatory markers such as C-reactive protein and erythrocyte sedimentation rate. The fat layer, in other words, appears to track cardiac function more faithfully than systemic inflammation does.

Multiple linear regression then asked which factors independently predict strain when confounders are accounted for. With GLS as the dependent variable and mean fat thickness, disease duration, sex, body mass index, LDL-C, HDL-C, and the E/A ratio entered as predictors, mean epicardial fat thickness emerged as the strongest and only statistically significant independent determinant (standardized β = −0.497, p < 0.001). The non-standardized coefficient of −0.932 translates into a concrete clinical rule of thumb: for every 1-millimeter increase in mean fat thickness, global longitudinal strain drops by roughly 0.93 percentage points. The model explained about 32% of the variance in strain, and reliability testing showed excellent reproducibility, with intraobserver intraclass correlation coefficients ranging from 0.859 to 0.981 and interobserver values from 0.844 to 0.969.

Why would lupus drive this fat layer to thicken and turn hostile? The authors frame it as a localized manifestation of systemic chronic inflammation within a heart-specific depot. Against a background of persistent immune activation, macrophages within the tissue shift from anti-inflammatory M2 polarization toward pro-inflammatory M1, mast cells and Th17 cells infiltrate, and the tissue secretes elevated IL-1β, IL-6, and TNF-α. IL-1β exerts a negative inotropic effect by interfering with calcium-handling proteins, while TNF-α promotes myocardial fibrosis. Adiponectin expression falls, weakening its restraint on the NF-κB pathway, while leptin and resistin rise, fueling endothelial dysfunction and oxidative stress. Reactive oxygen species accumulate, mitochondrial function deteriorates, and the AGEs-RAGE signaling pathway amplifies the inflammatory loop. The result is a vicious cycle of systemic inflammation, local fat activation, and cardiac dysfunction — one that also promotes fibrosis through TGF-β and HIF-1 signaling and extracellular matrix remodeling through MMP-TIMP imbalance.

The clinical implication is that epicardial fat thickness, measured on a routine echocardiogram, could serve as an accessible imaging biomarker of cardiovascular risk in lupus — a way to flag subclinical myocardial involvement earlier than ejection fraction or symptoms ever could. Combined assessment of fat thickness with global longitudinal strain may help clinicians identify patients who need closer surveillance or earlier intervention, before irreversible remodeling sets in. The authors caution that their study is observational and cross-sectional, so causality cannot be established: it remains possible that fat thickening drives cardiac dysfunction, that declining cardiac function and metabolic change drive fat accumulation, or that both share a common cause. The sample was small, confined to adults, and drawn from a single center, and speckle-tracking algorithms are not yet fully standardized across ultrasound manufacturers. Even so, the convergence of findings — thicker fat, weaker strain, diffuse territory-wide deficits, and an independent dose-like relationship — makes a compelling case that the fat on the surface of the lupus heart is not innocent bystander tissue but an active participant in the disease’s quiet assault on the myocardium.

Subject of Research: The correlation between epicardial adipose tissue thickness and left ventricular systolic function in patients with systemic lupus erythematosus

Article Title: The correlation between epicardial adipose tissue thickness and left ventricular systolic function in patients with systemic lupus erythematosus

Article References: Lin, S., Zhang, S., & Zhou, H. (2026). The correlation between epicardial adipose tissue thickness and left ventricular systolic function in patients with systemic lupus erythematosus. Frontiers in Cardiovascular Medicine, 13, Article 1806431. https://doi.org/10.3389/fcvm.2026.1806431

Image Credits: AI Generated

DOI: 10.3389/fcvm.2026.1806431

Keywords: correlation, between, epicardial, adipose, tissue, thickness, left, ventricular, systolic, function, patients, systemic