Immediate and Long-term Effect of Exercise on Heart Rate Variability in Coronary Artery Disease

ABSTRACT

OBJECTIVE: To evaluate the dynamics of autonomic nervous activity at rest and immediately after maximum exercise using heart rate variability (HRV) in coronary artery disease (CAD) and to assess the long-term effect of exercise. METHOD: Time and frequency domain of HRV was measured in 18 normal subjects, 37 CAD patients with percutaneous transluminal angioplasty and 10 CAD patients with coronary artery bypass graft at rest and 1 hour after peak graded treadmill exercise. Nineteen CAD patients were exercised with moderate intensity during 4 month and HRV was measured. RESULTS: At rest, the standard deviation of the NN interval (SDNN) and low frequency was significantly lower in both CAD groups than in normal subjects. At recovery stage after maximum exercise, low frequency and low frequency/high frequency ratio was significantly lower in both CAD groups than in normal subjects. SDNN at recovery stage in normal subjects remained significantly below the baseline. There was no significant change in HRV after long-term exercise even though maximum oxygen uptake had improved. CONCLUSION: This study demonstrated the reduced control of autonomic nervous activity in CAD patients at rest and immediately after peak exercise. There was no change in HRV after long-term exercise.