The Influence of Epicardial Fat and Nonalcoholic Fatty Liver Disease on Heart Rate Recovery in Metabolic Syndrome

Abstract

Background: Epicardial adipose tissues reflecting visceral fat accumulations of the heart are associated with metabolic syndrome (MetS) and can be a predictor of other cardiometabolic diseases. It can adversely influence autonomic nervous system (ANS) of heart. Heart rate recovery (HRR) is an easy method for measuring ANS dysfunction. The purpose of this study was to determine whether epicardial fat thickness (EFT) and nonalcoholic fatty liver disease (NAFLD) are related to HRR in patients with MetS. Methods: We enrolled 772 consecutive patients from a health-screening center who underwent abdominal ultrasonography, treadmill test, and cardiac echocardiography. EFT using echocardiography and HRR by symptom-limited exercise testing was assessed. According to the presence of MetS and NAFLD, patients were classified into the four groups. Results: In NAFLD patients, EFT was higher and HRR was lower, especially in patients with MetS and NAFLD, compared to non-MetS participants without NAFLD (MetS with NAFLD, EFT 7.5 +/- 4.4mm, HRR 31.9 +/- 12.7; MetS without NAFLD, EFT 4.9 +/- 3.0mm, HRR 39.5 +/- 11.1; non-MetS with NAFLD, EFT 5.9 +/- 3.6mm, HRR 36.6 +/- 12.7; and non-MetS without NAFLD, EFT 4.4 +/- 3.5mm, HRR 43.4 +/- 14.5, p < 0.001). Patients with severe liver steatosis (LS) showed significantly higher EFT than those with moderate LS (14.2 +/- 2.0 vs. 7.5 +/- 3.1mm, P < 0.001), and EFT was positively correlated with severity of LS (r = 0.431, P < 0.001). HRR was significantly correlated with EFT (r=-0.386, P < 0.001) and severity of LS (r=-0.324, P< 0.001). Conclusions: EFT and NAFLD were significantly correlated with HRR in patients with MetS and they may be highly related to increased cardiovascular risk. These results suggest a cross-link among EFT, NAFLD, and cardiac autonomic dysfunction in patients with MetS.