Heart rate variability associates with asymptomatic coronary atherosclerosis

Area of Science:

• Cardiology
• Autonomic Nervous System Function
• Cardiovascular Research

Background:

• Heart rate variability (HRV) is often impaired in symptomatic coronary artery disease (CAD), especially post-myocardial infarction.
• The precise mechanisms linking CAD to impaired cardiac autonomic regulation remain unclear.
• It is debated whether coronary atherosclerosis or myocardial ischemia/injury is the primary driver of autonomic dysfunction in CAD.

Purpose of the Study:

• To investigate the relationship between coronary atherosclerosis severity and cardiac autonomic regulation.
• To determine if coronary atherosclerosis itself, independent of myocardial ischemia, affects HRV.
• To explore the impact of CAD on autonomic balance in asymptomatic individuals.

Main Methods:

• Quantitative coronary angiography was performed on 30 subjects with high familial risk for CAD but no history of myocardial ischemia.
• Heart rate variability (HRV) was assessed using 24-hour ambulatory ECG recordings, analyzing time-domain, frequency-domain, and non-linear parameters (SD1, SD2).
• Myocardial ischemia was ruled out using Tc-99m sestamibi scintigraphy at rest and during exercise.

Main Results:

• Coronary angiography showed significant stenosis in major coronary arteries (LAD, LCx, RCA).
• A significant inverse correlation was observed between HRV parameters (pNN50, HF spectral power, SD1/SD2 ratio) and the global severity and extent of coronary artery stenosis.
• These findings indicate a relationship between the degree of coronary atherosclerosis and altered autonomic function.

Conclusions:

• Coronary atherosclerosis severity is associated with a shift in cardiac autonomic regulation toward sympathetic predominance.
• This shift occurs in asymptomatic individuals even without evidence of myocardial ischemia.
• The study suggests that coronary atherosclerosis itself plays a role in impairing cardiac autonomic regulation.