Autonomic Imbalance and Heart Rate Variability in Korean with Metabolic and Cardiovascular Risk Factors

Background: Heart rate variability (HRV) may be used to assess autonomic imbalances. In this study, we investigated whether autonomic imbalance and HRV related with metabolic syndrome components and whether the association has any differences by various risk factors in Korean population.
Methods: We selected the participants who underwent HRV test including physical examination and blood sampling to measure abdominal circumference (AC), blood pressure (BP), fasting plasma glucose (FPG), serum triglyceride (TG), and serum HDL-cholesterol level. The subjects were grouped by quartile of HRV indices: standard deviation of NN intervals (SDNN), 5 minutes total power (TP), low frequency (LF) and high frequency (HF). We analyzed the prevalence of abdominal obesity, high BP (≥130/85 mmHgr), elevated FPG (≥100 mg/dL), high TG (≥150 mg/dL), and low HDL (men < 40 mg/dL, women
Results: In quartile analysis of HRV parameters by metabolic syndrome component, in men, high BP and high FPG were inversely related to SDNN, TP, LF and low HDL was related to HF. In women, high BP, high TG, low HDL, and abdominal obesity were inversely related to SDNN and TP, and high TG and abdominal obesity were inversely related to LF and HF. Low HDL was significantly related inversely to HF. After adjustment for age, the highest odds ratio was seen in quartile of SDNN for abdominal obesity in women. The lowest quartile group of SDNN had the risk of abdominal obesity as 4.607 times compared with the highest quartile group of SDNN (95% confidence interval, 1.146-17.719; P=0.031).
Conclusion: Low HRV was generally associated with most metabolic and cardiovascular risk factors. Especially abdominal obesity of women showed the highest odds ratio compared with the other risk factors.