L-Carnitine plays a role in the utilization of fatty acids and glucose in the myocardium. Previous studies have indicated carnitine deficiency in patients with congestive heart failure. However, the extent of altered carnitine metabolism and leftventricular function is not fully determined. This study is designed to determine if plasma L-carnitine levels can serve as a marker for impaired left ventricular function in patients with congestive heart failure.