Role of Metabolically Active Drugs in the Management of Ischemic Heart Disease

This article reviews the fundamentals of myocardial energy metabolism and selectively outlines the use of several metabolically active drug therapies in the treatment of ischemic heart disease. These drugs — ranolazine, trimetazidine, dichloroacetate (DCA), glucose-insulin-potassium (GIK) solutions, and L-carnitine — have mechanisms of action distinct from traditional anti-ischemic drugs. These agents work by shifting myocardial energy metabolism away from fatty acids toward glucose as a source of fuel. Because these agents are well tolerated and do not affect heart rate or blood pressure, they conceivably could supplement traditional anti-ischemic drug therapy with little risk. The background, rationale for use, and published literature on each agent is reviewed, and the outcomes of pertinent clinical trials are discussed. In the case of ranolazine, data suggest benefit in the treatment of stable angina pectoris, particularly with sustained release formulations. Trimetazidine appears to have similar physiologic effects to ranolazine, and it is effective as monotherapy and as additive therapy in patients with chronic ischemic heart disease. DCA improves acidosis in critically ill patients and, likewise, improves myocardial hemodynamics in those with chronic coronary artery disease and congestive heart failure; however, its metabolism is variable and clinical data on its use in chronic ischemic heart disease are limited. GIK solutions have been shown to be beneficial in animal and human models of ischemia and acute myocardial infarction, and they offer an inexpensive means by which to improve the oxidation of glucose in the heart. Lastly, a large body of literature suggests a benefit with L-carnitine in a number of cardiovascular illnesses, including ischemic heart disease. Clinical trial data in acute myocardial infarction are promising and have prompted the initiation of a large-scale mortality trial.