Abstract
BACKGROUND: Excess epicardial fat volume (EFV) has been recently implicated in cardiovascular structural and functional abnormalities. It has been associated with abnormal microvascular stiffness (as reflected by radial artery waveform; C2), which may result in microvascular dysfunction and contribute to the atypical chest pain syndrome without obstructive coronary artery disease (CAD). Women have been statistically shown to present with atypical chest pain more often than men and specifically without obstructive CAD. The aim of this study is to assess whether excess EFV in female subjects is associated with significant microvascular dysfunction (i.e., C2), in subjects without obstructive CAD. RESULTS: We screened 596 asymptomatic subjects, ages 20-79, using the Early Cardiovascular Health Risk Scoring System (ECVHRS), which has been reported. Out of the 596 total subjects, 230 subjects had a CACS. Out of these 230 subjects, 77 subjects (45 females; 32 males) had a 0 CACS. The 45 females from this cohort were the subjects of this study, and they were further categorized into 3 groups: group 1 (normal EFV, non-obese female subjects; n=16), females with ECVHRS < 3 and ACC/AHA risk score < 5%; group 2 (n = 9), females with elevated EFV and no abdominal visceral obesity; and group 3 (n=20), females with elevated EFV and abdominal visceral obesity. The average EFV was determined to be 72±20 cm(3) among group 1, which indicates the values for normal EFV. The results in group 2 indicate that excess EFV is contributing to the development of microvascular dysfunction, resulting in abnormal micro-arterial (C2) elasticity (p< 0.00001), increase in resting blood pressure (p =0.0001), an abnormal rise in blood pressure (BP) at rest and post-mild protocol exercise (PME) (p = < 0.00001), and abnormal increase in carotid intima-media thickness (CIMT) (p = 0.000164). CONCLUSION: Excess EFV appears to be not only a novel cardiovascular risk marker, but also the culprit for other cardiovascular risk markers. Based on these findings, elevated EFV may contribute to the development of the atypical chest pain syndrome in females without obstructive CAD. Additionally, EFV is emerging as a potential clinically relevant significant cardiovascular risk biomarker and may become a target to reduce cardiovascular morbidity and mortality.