Cardiovascular Risk Factors and Sympatho-vagal Balance: Importance of Time-domain Heart Rate Variability

Objective: Cardiovascular Disease (CVD) is the leading cause of death and disability worldwide. sDyregulation of the autonomic nervous system associated with various pathological conditions often occurs in presence of cardiovascular risk factors. Heart Rate Variability (HRV) may be used to assess autonomic imbalances. The aim of our study is to evaluate the correlation between HRV and the main cardiovascular risk factors in subject who underwent digital ambulatory 24 hours Holter ECG monitoring for clinical investigations. Methods: We evaluated time domain parameters of HRV by Holter ECG monitoring in a large population categorized based on the presence or absence of the major cardiovascular risk factors. Results: We found significant differences in time domain parameters of HRV in patients with and without common risk factor for CVD such as diabetes, family history for Coronary Artery Disease and dyslipidemia. We also analyzed our study population based on age and we found a positive correlation with the standard deviation of all NN intervals (SDNN), square root of the mean of the sum of the square of the differences between adjacent NN intervals (RMSSD), mean R-R intervals and by the number of adjacent NN intervals differing by more than 50 ms divided by the total number of all NN intervals (pNN50) and an inverse correlation for the others parameters. Conclusion: Non-modifiable risk factors (age, gender, family history) along with dyslipidemia and diabetes, are related to a change in HRV, while modifiable risk factors (smoking, hypertension, overweight, hyperhomocysteinemia) showed no correlation. This would seem to indicate that the genetic components more than lifestyle habits and behavior act on the nervous control of the heart. Our study shows the possibility to find interesting clinical-prognostic data, analyzing simple parameters obtained from instrumental methods of investigation performed for other clinical reasons.