Abstract Body (Do not enter title and authors here): Background: Angina with no obstructive coronary artery disease (ANOCA) is common in women and often linked to coronary microvascular dysfunction (CMD). Epicardial adipose tissue (EAT), a metabolically active fat depot sharing microcirculation with the myocardium, may promote CMD through inflammatory signaling. T1 relaxation time and saturated fatty acid (SFA) fraction are emerging CMR-derived markers of adipose inflammation and lipid content. We hypothesize that altered EAT composition—characterized by lower T1 and elevated SFA—reflects a pro-inflammatory state and is associated with impaired myocardial perfusion in women with ANOCA.
Methods: This was a single-center, prospective study. Subjects underwent CMR scan at 1.5T (Aera), including rest and regadenoson stress perfusion with automated inline global rest and stress myocardial blood flow (MBF), myocardial perfusion reserve (MPR). EAT volume (EATV), Native EAT T1 and EAT SFA were measured using different CMR images. (Figure 1). Pearson correlation coefficients and multivariable linear regression adjusted for age were used to assess associations between EAT biomarkers, MBF, and MPR. CMD was defined as MPR <2.4.
Results: Thirty-two women were recruited (Figure 2). Ten (32%) of women had CMD. EAT T1 was moderately correlated with stress MBF (r=0.50, p=0.01) and MPR (r=0.4, p=0.05) (Figure). EAT SFA was moderately negatively correlated with stress MBF (r=-0.47, p=0.04), MPR (r=-0.49, p=0.03) (Figure). EATV index (EATVI) showed moderate correlation with stress MBF (r=0.4, p=0.03), but no significant association with MPR (p=0.28) (Figure 3). After adjusting for age, each 10 ms decrease in EAT T1 was associated with a 0.17 ml/min/g reduction in stress MBF (β = 0.17, 95% CI: 0.05, 0.29, p = 0.01), and a 0.17 reduction in MPR (β = 0.17, 95% CI: 0.02, 0.33, p =0.04). Additionally, each 0.01 increase in SFA was associated with a 0.05 ml/min/g reduction in stress MBF (β = -0.05, 95% CI: -0.10, -0.01, p = 0.05), and a 0.06 reduction in MPR (β = -0.06, 95% CI: -0.12, -0.05, p =0.04).
Conclusion: CMR-derived EAT T1 relaxation time and SFA fraction are associated with CMD in women with ANOCA. Elevated SFA and reduced T1, reflective of a pro-inflammatory adipose phenotype, are independently associated with impaired myocardial perfusion. These findings support a potential mechanistic link between EAT metabolic dysfunction and CMD and underscore the value of multiparametric CMR in the phenotyping at-risk women with ANOCA.