Association between Echocardiographic Epicardial Adipose Tissue Thickness and Atrial Fibrillation in a Single-Centre Pakistani Cohort

Objectives: To assess the association between echocardiographic epicardial adipose tissue (EAT) thickness and atrial fibrillation (AF) in a single-centre Pakistani cohort of patients referred for transthoracic echocardiography (TTE). Methods: Patients referred for TTE at Aga Khan University Hospital (AKUH), Karachi, were prospectively enrolled over a six-month period (1 September 2024 – 28 February 2025) using a convenience sampling approach; nearly all patients referred for TTE with AF during this period were captured, while patients in sinus rhythm were enrolled by convenience sampling alongside them, in order to ensure an adequate number of AF cases for comparison. EAT was measured in the parasternal long-axis view at end-systole, defined as the echo-free space between the right ventricular free wall and the pericardium. Results: The final cohort comprised 401 patients (median age 66 years, IQR 56–74; 204 [51%] male). AF prevalence in this enriched cohort was 50% (200/401), reflecting the enrolment strategy rather than the true prevalence of AF among unselected TTE referrals. Each 1-mm increase in EAT thickness was independently associated with higher odds of AF after adjustment for age, sex, BMI, hypertension, diabetes, coronary artery disease, and LV ejection fraction (< 55% vs ≥ 55%) (adjusted OR 1.60, 95% CI 1.32–1.97, P < 0.001), and this association was not attenuated by additional adjustment for left atrial volume index (adjusted OR 1.60, 95% CI 1.30–2.00, P < 0.001). In a categorical sensitivity analysis, adjusted odds of AF were 6.89-fold (95% CI 3.18–16.3) and 12.5-fold (95% CI 5.14–33.1) higher in the 4–5 mm and ≥ 6 mm EAT groups, respectively, relative to ≤ 3 mm (trend P < 0.001). Conclusions: In this cohort, higher EAT thickness was independently associated with a higher prevalence of AF, an association that persisted after adjustment for established clinical and echocardiographic confounders. Given the cross-sectional design, these findings describe an association rather than a predictive or causal relationship; EAT measured by TTE may merit further prospective evaluation as an accessible cardiometabolic marker in this population.