In patients with stable coronary artery disease, a glucose insulin potassium (GIK) solution may increase arterial glucose and the arterial coronary sinus difference of glucose across the myocardium. In the same patients, GIK may reduce arterial free fatty acids as well as the arterial coronary sinus difference of free fatty acids across the myocardium. As the arterial values of free fatty acids fall, so does the arterial coronary sinus difference of free fatty acid across the myocardium, defining a myocardial threshold for free fatty acids of approximately 200 mEq/L. Glucose insulin potassium may lower free fatty acid values to near or below myocardial threshold in patients with acute myocardial infarction despite recurrent pain. Preliminary data suggest that GIK in the concentration and infusion rates used in this study may favorably influence survival in patients with acute myocardial infarction.