Obstructive sleep apnea (OSA) is a highly prevalent condition in patients with coronary heart disease and is associated with impaired exercise performance, functional limitation and reduced health-related quality of life. The investigators hypothesize that identification and treatment of OSA in patients undergoing cardiac rehabilitation will improve the response to rehabilitation. The proposed study will test this hypothesis using a parallel group, randomized, clinical trial comparing OSA treatment with continuous positive airway pressure (CPAP) to an educational control group in patients undergoing cardiac rehabilitation who screen positive for previously undiagnosed OSA.