Heart rate variability associates with asymptomatic coronary atherosclerosis

Heart rate variability (HRV) becomes impaired in symptomatic coronary artery disease (CAD), particularly, after myocardial infarction. The mechanism how CAD results in impairment of cardiac autonomic regulation is not known. Whether it results rather from coronary atherosclerosis itself than myocardial ischemia and myocardial injury has remained elusive.

Quantitative coronary angiography was performed in 30 subjects without history of myocardial ischemia, but with high familial risk for CAD. HRV was measured from 24-h ambulatory ECG recordings in time and frequency domain and also non-linear HRV variables SD1 and SD2 in Poincare plot were calculated. Myocardial ischemia was excluded by Tc-99m sestamibi scintigraphy at rest and during exercise.

Coronary angiography revealed mean diameter stenosis of 32 ± 19 % in left anterior descending coronary artery, 26 ± 16 % in left circumflex coronary artery and 25 ± 20 % in right coronary artery. An inverse correlation was found between pNN50 and global severity of coronary artery diameter stenosis (r = -0.415, p < 0.05). Correspondingly, power of HF spectral component correlated negatively with global extent of coronary atherosclerosis (r = -0.366, p < 0.05). In Poincare plot, SD1/SD2 ratio correlated with global extent (r = -0.394, p < 0.05) and global burden (r = -0.388, p < 0.05) of coronary arteries.

The severity and extent of coronary atherosclerosis were related to a shift of cardiac autonomic regulation towards sympathetic predominance in asymptomatic subjects without evidence of myocardial ischemia.