Cardiac Rehabilitation (CR) is an effective exercise-based lifestyle therapy for patients with cardiac disease. There are two common methods of exercise prescription, an effort based exercise prescription and target heart rate based exercise prescription. The purpose of this research study is to identify the best way to exercise in cardiac rehabilitation. There are three main goals of this study. First, the investigators want to know if an exercise test should be done near the beginning of cardiac rehabilitation. Second, the investigators want to understand what type of exercises should be recommend to patients. Third, the investigators want to understand if a personal heart rate monitor will improve adherence to a target heart rate for exercise. As part of this study, some patients will undergo an exercise stress test on a treadmill to determine a target heart rate. These patients will be given a heart rate goal to use when they exercise. Some patients will be given a personal heart rate monitor to improve adherence.

Cardiac Rehabilitation (CR) is an effective exercise-based lifestyle therapy for patients with cardiac disease that reduces cardiovascular morbidity and mortality, increases quality of life, and is cost-effective. Recent retrospective studies show that higher exercise gains during CR are associated with reduced long-term morbidity and mortality among patients with both coronary artery disease and systolic heart failure. However, it is unclear which methods maximize exercise gains in CR. Recent retrospective studies have suggested that performing stress testing early in CR may allow for better tailoring of an exercise prescription and thus increase exercise gains. In this study, the investigators propose to do a randomized controlled trial of 60 patients at Baystate Medical Center CR, in which two thirds of the patients will undergo exercise testing prior to starting CR. The exercise test will determine the initial target heart rate range (THRR) and will also influence subsequent exercise progression. Additionally, half of the patients undergoing a stress test will receive a personal heart rate monitor to help improve adherence to the exercise prescription and THRR. The primary outcome is to determine feasibility, protocol fidelity, and effect sizes in preparation for a fully powered subsequent trial that will measure the impact of stress testing and a target heart rage range exercise prescription on exercise gain during CR.

Inclusion Criteria:

• Patients who are referred with an eligible diagnosis to CR.
• Patients with myocardial infarction, percutaneous coronary intervention, or bypass surgery

Exclusion Criteria:

• Permanent Atrial fibrillation, as this would interfere with using a target heart rate range during cardiac rehabilitation.
• Patients with pacemakers, as the polar heart rate monitor interferes with pacing lines on the telemetry system.
• Stable angina, as chest pain could become a limiting factor as exercise training progresses, rather than using target heart rates.
• Patients with high risk unrevascularized coronary artery disease including left main coronary disease >60% or proximal left anterior descending artery (LAD) >80%, per the discretion of the medical director.
• Patients with heart transplant or left-ventricular assist device, as heart rates can be inaccurate and difficult to measure.
• Patients who plan to attend fewer than 12 sessions of CR, for reasons that might include need to return to work, high copays, transportation, lack of insurance, or lack of interest in the program.
• Patients who join the Baystate CR program after having completed more than 3 sessions of CR at a different CR program.
• Major orthopedic limitations to exercise, such as history of amputation or exercise-limiting joint pain, or inability to walk on a treadmill, because all patients will have to complete a stress test on a treadmill and objective data collected during CR will be recorded during treadmill exercise.
• Patients who plan to undergo a clinically indicated stress test in the next 3 months as this would potentially interfere with the exercise prescription in the control group.
• Any elective hospitalization or revascularization procedure (such as PCI or CABG) that are planned to occur in the next 3 months. These could interrupt exercise training or change target heart rate ranges.
• Any other condition in which exercise training or exercise testing would be contraindicated such as severe uncontrolled hypertension, diabetes, arrhythmia, or severe valvular disease, as determined by the Medical Director of Cardiac Rehabilitation.
• Any other condition that would prohibit adherence to study protocols, such as active drug use, or untreated mental health conditions that would interfere with following instructions.
• Patients judged to be at very high or high-risk of early drop-out, per current program risk stratification

De-identified individual participant data for all primary and secondary outcome measures will be made available.

Data will be available within 12 months of study completion.

Data access requests will be reviewed by an external independent review panel. Requestors will be required to sign a data access agreement