Deterioration in left ventricular function, which is characteristic in patients with congestive heart failure, appears to be a multifactorial process. Beta-blockers appear to reverse the deterioration and frequently improve left ventricular function in patients with both ischemic and non-ischemic cardiomyopathies. The mechanism by which beta-blockers improve ejection fraction is not known. Although it is well established that regional flow, function and metabolism may improve after coronary revascularization whether beta-blocker therapy will have similar salutary results in patients with congestive heart failure is unknown. The aim of this study is to: 1) quantitate regional glucose uptake and regional blood flow before and after chronic beta-blocker administration to patients with congestive heart failure using positron emission tomography, 2) determine if alteration in either regional glucose or lipid uptake or regional blood flow correlate with improvement in wall motion and global left ventricular function, and 3) determine if ischemic and nonischemic myocardium differ in blood flow or metabolism.