The objective of this project is to assess the effectiveness of a new modality of prescribing the intensity of physical exercise in cardiovascular rehabilitation programs according to physiological criteria (heart rate variability measured every morning) in comparison to a standard non-individualized program.

In coronary artery disease patients, cardiovascular rehabilitation (CR) reduces cardiac mortality by 30% when compared to usual drug therapy without CR. Cardiorespiratory fitness (VO2peak) is the most powerful independent prognostic marker of longevity. An improvement in VO2peak is also associated with better cognitive performance in the elderly.

The effectiveness of CR varies between patients. About 25% of coronary disease patients do not improve their VO2peak after taking part of a CR program. The risk of acute event for those "non-responder" patients, (i.e. not increasing their VO2peak), is high with a mortality rate three times higher compared to "responder" individuals.

It seems that the autonomic nervous system (ANS) is playing an important role in exercise training-induced physiological responses. Based on this, it has been proposed in healthy subjects to prescribe each exercise session according to ANS parameters (via heart rate variability, HRV). It has been suggested that high-intensity exercise when HRV parameters are stable, results in better adaptations to training. Conversely, recovery sessions when HRV is impaired seem necessary.

44 participants with stable coronary artery diseases, and taking part in a CR program will be included in this study. All participants will have signed a written consent form before taking part in the study. Patients will be randomly assigned to one of the 2 following study arms: 1/ standard exercise training ; 2/ Heart Rate Variability-guided exercise training.

Inclusion Criteria:

• Coronary artery disease patient from the Montreal Heart Institute
• Age> 18 years old
• Referred to the EPIC center in a cardiovascular rehabilitation program due to stable angina pectoris, acute coronary syndrome (with or without ST segment elevation) or after complete coronary revascularization (primary or elective) by Percutaneous Coronary Intervention.
• Able to perform a maximal cardiopulmonary exercise stress test in accordance with current cardiovascular rehabilitation recommendations.
• Able to read, understand and sign the information and consent form.

Exclusion Criteria:

• Any absolute and relative contraindication to the maximal exercise test and / or physical activity.
• Recent cardiovascular events (cardiac decompensation or treatment with positive inotropic drugs or angioplasty less than 10 days, cardiac surgery less than 1 month, valve disease requiring surgical correction, active myopericarditis, severe ventricular arrhythmias not stabilized under treatment).
• Revascularization by coronary artery bypass grafting
• Atrial fibrillation
• Renal failure
• Heart failure
• Diabetes

This clinical trial is a double-blinded study. Patients, and research personnel performing the outcome assessments and investigators will be blinded to group allocation. Only the kinesiologists will be aware of the group allocation.