Coronary artery bypass grafting improves 3-year survival by approximately 30% to 50% and physical functioning by approximately one New York Heart Association class in patients with moderate to severe left ventricular dysfunction and limiting angina. However, the operative mortality ranges from 5% to 30% depending on patients' ejection fractions and comorbidity. It is not clear whether patients whose predominant symptom is heart failure rather than angina benefit from bypass surgery or how much ischemia is required to justify surgical intervention. Clinical outcomes after angioplasty have not been adequately studied to determine the relative risks and benefits compared with bypass grafting.