Impaired coronary flow reserve is associated with increased echocardiographic epicardial fat thickness in metabolic syndrome patients.

Objectives: Metabolic syndrome (MetS) is a strong predictor of cardiovascular events and coronary flow reserve (CFR), an indicator of microvascular function, has been found to be impaired in MetS. Epicardial fat thickness (EFT) reflects visceral adiposity and is considered an important cardiometabolic marker. In this study, we aimed to examine the presence of an association between CFR and EFT in MetS patients.

Methods: Forty-six MetS patients (25 men, mean age 47.3±6.6 years) and 44 age-matched and sex-matched controls (24 men, mean age 46.0±6.1 years) were prospectively studied. Both CFR and EFT were measured by transthoracic echocardiography. Peak diastolic coronary flow velocities were measured in the left anterior descending artery by pulsed wave Doppler at the baseline and after adenosine infusion, and CFR was calculated as the ratio of hyperemic to baseline velocities.

Results: The waist circumference, total and low-density lipoprotein-cholesterol, fasting glucose, triglycerides, systolic and diastolic blood pressures, and high sensitive C-reactive protein were significantly higher in MetS patients. The mean EFT was significantly higher in MetS patients compared with the controls (8.7±0.2 vs. 4.8±0.1 mm, P<0.001); however, CFR was significantly lower in MetS patients (2.3±0.2 vs. 2.7±0.2, P<0.001). CFR was correlated significantly with BMI, waist circumference, high-density lipoprotein-cholesterol, triglycerides, fasting glucose, high sensitive C-reactive protein, and EFT. In regression analysis, MetS itself and EFT were found to be independent predictors of impaired CFR.

Conclusion: CFR is impaired in MetS patients. MetS itself and increased EFT are associated independently with coronary microvascular dysfunction and EFT is a predictor of worse CFR even after accounting for the presence or absence of the MetS.