Comparison of time domain heart rate variability parameters between smokers and non-smokers

Background: Cigarette smoking induced sympathetic overdrive is one of the major independent modifiable risk factors for cardiovascular mortality and morbidity. There is altered autonomic activity with increased adrenergic activity in chronic smoking which also predisposes to cardiovascular morbidity and mortality. There are several tests that can determine the Autonomic Activity. Among them, heart rate variability (HRV), especially the time domain parameters of it, is simple, easy to perform, and non-invasive test for diagnosing autonomic dysfunction in the smokers. Aims and Objectives: The aims of this study were to compare the time domain parameters of HRV in smokers and non-smokers. Materials and Methods: The present study was carried out at autonomic function laboratory and cardiovascular function laboratory, Department of Physiology, Government Medical College, Bhavnagar, among 200 subjects, out of which 100 were smokers and 100 were non-smokers, in age group of 20–50 years. Results: There was a significant increase in mean heart rate, blood pressure, and R-R interval in smokers as compared to the non-smokers. There was also a significant decrease in all time domain parameters of HRV which suggests profound sympathetic overdrive and a decrease in vagal tone due to the actions of nicotine presents in tobacco smoke. Conclusions: Cigarette smoking plays a major role in degradation and decreased function of autonomic nervous system.