Impact of epicardial adipose tissue on coronary microvascular dysfunction in patients with nonobstructive coronary artery disease

Background Coronary microcirculation plays a fundamental role in regulating coronary blood flow, a key response to cardiac oxygen requirements. Coronary microvascular dysfunction (CMD) is defined as impairment of this mechanism, and is a risk factor for adverse cardiovascular clinical outcomes. Epicardial adipose tissue (EAT) may be involved in the development of systemic inflammation-dependent microcirculatory dysfunction, and concomitant CMD. Furthermore, excess EAT may alter myocardial function via local effects, resulting in mechanical restraint and intramyocardial fat deposition. However, the influence of EAT on CMD is poorly understood in the context of ischemia with nonobstructive coronary artery disease. Purpose This study aimed to evaluate our hypothesis that EAT surrounding the coronary microvasculature directly affects coronary microcirculation, to gain insight into the influence of EAT on CMD Method This prospective single-center study enrolled 184 patients with chest discomfort/heart failure with ischemic ECG change who underwent invasive functional coronary angiography due to suspected myocardial ischemia from November 2022 to February 2025. Exclusion criteria were undergoing dialysis and administration of catecholamines. Guidewire-based assessments of coronary blood flow were performed at rest and during interrogation with adenosine. CMD was diagnosed as absence of obstructive coronary artery (fractional flow reserve > 0.80) and impaired coronary flow reserve (CFR < 2.5) or high index of microvascular resistance (IMR > 25). The EAT volume and abdominal visceral adipose tissue (AVAT) area were measured using multislice computed tomography. Results We recruited 81 patients (49 males, mean age 71 ± 13 years) with a diagnosis of nonobstructive coronary artery disease. CMD was present in 40 (49 %), 25 had high-IMR and 27 patients had impaired CFR. The CMD group was found to have increased EAT volume was increase in patients with CMD compared in patients without CMD (120 ± 45 cm³ vs. 100 ± 37 cm³, p = 0.038) (Figure). EAT volume increased in the high-IMR compared with the low-IMR group (135 ± 43 cm³ vs. 99 ± 37 cm³, p < 0.01, 141 ± 62 cm² vs. 95 ± 56 cm², p < 0.01, respectively), but were not significantly different between high- and low-CFR groups. Univariate regression analysis revealed EAT volume and AVAT area to be associated with increased frequency of IMR (odds ratio: 1.02, p < 0.01; odds ratio: 1.00, p = 0.01, respectively), but the association between AVAT and CMD disappeared after adjustment for multivariable analysis (Table). Conclusions EAT volume, not AVAT area, was found to be associated with abnormal coronary microvascular resistance. Local effects by EAT may therefore influence the development of CMD.Comparison of EAT volume Logistic regression analysis for IMR>25