Assessing Autonomic Function in Smokers

Background Cigarette smoking is a major risk factor for the development of atherosclerosis, coronary heart disease, acute myocardial infarction, and sudden cardiac death. There is altered autonomic activity with increased adrenergic activity in chronic smoking which also predisposes to cardiovascular morbidity and mortality. To monitor the autonomic activity, Heart rate Variability (HRV) has emerged as efficient tool. Method A total of 60 subjects were included in the study out of which 30 were chronic smokers of at least 10 pack years and 30 were non smoker controls. The HRV was recorded in the supine subject in relaxed state. We recorded the frequency domain analysis [low frequency domain (LF), high frequency domain (HF) and LF/HF ratio] for which five minute recordings were taken and data was generated by the POLYRITE D system, supplied by RMS India P-Ltd. Chandigarh. Results Test group showed a significant (P<0.001) increase in heart rate with decreased RR interval as compared to control group. Also there was a significant (P<0.05) decrease in high frequency domain (HF) while there was a significant (P<0.05) increase in LF/HF ratio. There was a significant increase in heart rate (P<0.05) and LF/HF ratio (P<0.001) in the group with more than 15 pack years compared to less than 15 pack years, while there was a significant (P<0.05) decrease in RR interval, LF and HF values. Conclusion Smoking severely affects the cardiac autonomic functions which is evident with the study of heart rate variability, so the HRV should be included in routine investigations to access the severity of cardiac involvement in chronic smokers.