Background: Metabolic syndrome (MS) increases the risk of cardiovascular events. Heart rate variability (HRV) represents autonomic function and reduced HRV significantly increases cardiovascular mortality. In this study, we investigated whether each of the MS component is related to HRV indices.
Method: We analyzed 592 subjects who participated in routine health check up from February 2002 to October 2004. We measured their metabolic components and evaluated the relationships of MS and HRV indices.
Results: Entire sample was divided into 5 group according to the number of metabolic compononets. All results were adjusted for gender, age and mean heart rate. As increasing the number of metabolic components, SDNN (standard deviation of all normal RR intervals) was decreased (P for linear trend = 0.03) and LF/HF (low frequency/high frequency) was increased (P for quadratic trend = 0.01). Paticularly in men, obese group has statistically higher LF/HF than non-obese group has statistically higher LF/HF than non-obese group has statistically higher LF/HF than non-obese group (P = 0.0002). In women, hyperTG (Triglycerides) group has lower SDNN comparing to normal TG group (P = 0.04).
Conclusions: Metabolic syndrome adversely affects cardiac autonomic control and a reduced cardiac autonomic control may contribute to the increased risk of subsequent cardiovascular events in individuals who exhibit metabolic syndrome.

Keywords: Cardiac autonomic system, Heart rate variability (HRV), Metabolic syndrome (MS), Obesity, Triglycerides