Use of the amino acid supplement L-arginine following a heart attack does not improve certain cardiac functions and measurements and may be associated with an increased risk of death, according to a study in the January 4 issue of JAMA.L-arginine is a widely available dietary supplement and is publicized as having benefits for patients with hypertension, angina, heart failure and sexual dysfunction, according to background information in the article. Prior studies suggest that L-arginine has the potential to reduce vascular (blood vessel) stiffness.
Steven P. Schulman, M.D., of Johns Hopkins Medical Institutions, Baltimore, and colleagues conducted the Vascular Interaction with Age in Myocardial Infarction (VINTAGE MI) clinical trial to test whether administering L-arginine to patients following a first ST-segment elevation myocardial infarction (STEMI; a certain pattern on an electrocardiogram following a heart attack) over a 6-month period would decrease vascular stiffness and improve ejection fraction (a measure of how much blood the left ventricle of the heart pumps out with each contraction).
The randomized, double-blind, placebo-controlled trial included 153 STEMI patients; 77 were 60 years or older. Participants were enrolled from February 2002 to June 2004. Patients were randomly assigned to receive L-arginine (goal dose of 3 g three times a day) or matching placebo for six months.
The researchers found: "The VINTAGE MI study demonstrated that 6 months of L-arginine added to standard postinfarct medications did not reduce noninvasive measures of vascular stiffness, improve ejection fraction, or improve clinical outcomes. To the contrary, we noted a possible increased risk of death in older patients after infarction while taking L-arginine compared with those taking a placebo, leading to the early termination of the study. These findings have broad public health implications given the increasing availability and use of L-arginine in patients with and without established cardiovascular diseases."
Death occurred in 6 patients (8.6 percent) in the L-arginine group died during the 6-month study period vs. none in the placebo group.
"In conclusion, L-arginine therapy should not be given to patients following a myocardial infarction. It neither alters noninvasive measures of vascular stiffness nor improves left ventricular function. L-arginine therapy in older patients with diffuse atherosclerosis may worsen clinical outcomes," the authors write.