Heart Rate Variability in Metabolic Syndrome

ABSTRACT

BACKGROUND: Metabolic syndrome is a cluster of multiple cardiovascular risk factors. There are many suggestions that decreased Heart Rate Variability (HRV) is associated with cardiovascular disease. The purpose of this study was to find out the association between metabolic syndrome and HRV and to find out the affecting factors to HRV. METHODS: The study subjects were people who visited a health promotion or obesity center of a medical college in Suwon from January to February, 2002. Healthy 149 subjects were divided into two groups of metabolic vs non-metabolic syndrome. Mean Heart Rate (MHR), Standard Deviation of N-N interval (SDNN), The Square Root of the Mean Squared Difference of successive NN intervals (RMSSD), Total Power (TP), Low Frequency (LF), High Frequency (HF), and LF/HF ratio were used as the indices of HRV. T-test was used to compare the HRV of metabolic and non-metabolic syndrome, and multiple regression analysis was used to find out the affecting factors to HRV. RESULTS: HRV indices were significantly lower in metabolic syndrome. The mean+/-SD of SDNN, RMSSD, TP, LF, HF of metabolic vs non-metabolic syndrome was 39.2+/-14.5 vs 32.9+/-10.8 (ms, P=0.015), 30.5+/-14.6 vs 23.3+/-11.6 (ms, P=0.006), 1270.0+/-975.3 vs 893.2+/-652.6 (ms2, P=0.028), 354.4+/-410.8 vs 198.3+/-259.2 (ms2, P=0.008), 273.3+/-292.1 vs 148.9+/-137.2 (ms2, P=0.001), respectively. RMSSD and LF significantly decreased in the hypertensive group. Parameter estimate was 5.52 (ms, P=0.041), and 217.63 (ms2, P=0.002), respectively. TP and LF decreased as HDL cholesterol decreased. Parameter estimate was 24.31 (ms2, P=0.02), 11.12 (ms2, P=0.008), respectively. CONCLUSION: The HRV decreased in metabolic syndrome, and BP and HDL-cholesterol significantly affected HRV.