Abstract
Background: Coronary artery disease (CAD) is one of the leading causes of mortality and morbidity in India. There is a need to identify various risk factors leading to the onset and progression of the disease. Heart rate variability (HRV) analysis is one of the emerging non-invasive techniques to identify severity and prognosis of CAD. HRV is defined as the oscillation in the interval between consecutive heartbeats as well as the oscillations between consecutive instantaneous heart rates.

Aims and Objectives: The objective of this study is to identify the variations in HRV in patients with CAD.

Materials and Methods: A total of 30 male patients with CAD and 30 age- and sex-matched healthy adults aged 40–65 years, satisfying the inclusion and exclusion criteria, were enrolled in the study. Electrocardiography was recorded for 5 min and the frequency domain parameters were derived from it and compared between groups.

Results: The results of our study showed a higher parasympathetic activity determined by high-frequency power (HF) in control subjects as compared to cases. Sympathetic predominance was seen in cases as determined by low-frequency power (LF). LF/HF ratio was also significantly higher in cases indicating sympathetic predominance.

Conclusion: Sympathetic predominance with lowered parasympathetic activity observed in the cases puts them at a higher risk of adverse cardiac events. An attempt needs to be made to incorporate improvement of HRV as a modality of treatment of CAD.

Key words: Coronary Artery Disease; Heart Rate Variability; Autonomic Nervous System