The Autonomic Imbalance of Myocardial Ischemia during Exercise Stress Testing: Insight from Short-Term Heart Rate...

Area of Science:

• Cardiology
• Physiology
• Biomedical Engineering

Background:

• Exercise stress testing (EST) has limitations in diagnosing obstructive coronary artery disease (CAD).
• Heart rate variability (HRV) analysis may enhance the sensitivity of CAD detection during EST.
• Autonomic dysfunction is implicated in cardiovascular diseases.

Purpose of the Study:

• To evaluate the correlation between short-term HRV and myocardial ischemia during the acceleration, maximum, and recovery phases of EST.
• To compare HRV patterns during EST in healthy individuals and patients with varying degrees of CAD.
• To identify potential HRV-based markers for diagnosing significant CAD.

Main Methods:

• Collected HRV data during EST from 19 healthy controls (RHC) and 35 CAD patients (25 iCAD, 10 sCAD).
• Analyzed HRV indices including low-frequency power (LF), standard deviation of normal-to-normal intervals (SDNN), and Poincaré plot parameters (SD2).
• Compared HRV changes across acceleration, maximum, and recovery stages of heart rate (HR).

Main Results:

• All HRV indices decreased at maximum HR, with no significant differences between iCAD and sCAD groups.
• The low-frequency power (LF) in healthy controls recovered faster post-maximum HR compared to the significant CAD (sCAD) group.
• Relative changes in most HRV indices (LF, SDNN, SD2) between maximum HR and recovery were lower in the sCAD group than in RHC (p < 0.05).
• The recovery slope of LF was significantly smaller in the sCAD group (p = 0.02), indicating delayed sympathetic recovery.

Conclusions:

• Short-term HRV monitoring during EST offers valuable insights into cardiovascular autonomic imbalance in significant CAD.
• Delayed sympathetic recovery, reflected in HRV changes, may serve as an additional diagnostic marker for myocardial ischemia.
• HRV analysis during EST can potentially augment traditional diagnostic methods for obstructive CAD.