Association of sympathovagal imbalance with obesity indices, and abnormal metabolic biomarkers and cardiovascular parameters.

PROBLEM: Pathophysiological mechanisms contributing to abnormal cardiovascular (CV) parameters in obesity have not been fully elucidated. Role of sympathovagal imbalance (SVI) in the prediction of abnormalities in CV functions in obesity has not been studied.

METHODS

Anthropometric indices, CV parameters, autonomic function tests (AFTs) such as spectral heart rate variability (HRV) analysis, heart rate and blood pressure response to standing, deep breathing, and isometric-handgrip, and biochemical parameters like insulin resistance (HOMA-IR), lipid risk factors and inflammatory marker [high-sensitive C-reactive protein (hsCRP)] were assessed in control group (non-obese, n=43) and obese group (n=45). Association of anthropometric indices and abnormal CV parameters with low-frequency to high-frequency ratio (LF-HF) of HRV was performed by Pearson's correlation. Independent contribution of anthropometric indices and abnormal CV parameters to LF-HF was assessed by using a multiple regression analysis. LF-HF prediction of rate-pressure product (RPP), the indicator of CV dysfunction was assessed by logistic regression.

RESULTS

LF-HF, the marker of SVI was more in obese group compared to control group. AFTs of sympathetic activity were increased and of parasympathetic activity were reduced in obese group. Anthropometric indices, HOMA-IR, lipid risk factors and hsCRP were correlated with LF-HF. These metabolic biomarkers had independent contribution to SVI. Among, anthropometric indices, waist-to-height ratio (WHtR) had maximum association with LF-HF. LF-HF had significant prediction of RPP in obese group.

CONCLUSION

SVI in obesity is due to both increased sympathetic and decreased vagal activity. Abnormal CV parameters in obesity are linked to SVI, which is contributed by insulin resistance, dyslipidaemia and low-grade inflammation. LF-HF predicts abnormal CV parameters in obesity.