A trial being conducted by researchers at Johns Hopkins University was unexpectedly cut short due to safety concerns when it appeared that L-arginine, a popular dietary supplement, was associated with an increased risk of mortality in patients recovering from heart attack.
L-arginine has been touted as beneficial for patients with heart failure or following myocardial infarction.
According to Dr. Steven P. Schulman, a cardiologist at Johns Hopkins, the trial was suddenly stopped after only six months as a result of six deaths out of the 70 patients who were taking L-arginine. There were no reported deaths among individuals in the placebo group.
The report is published in the January 4 issue of the Journal of the American Medical Association.
Five of the patients who died while taking L-arginine were over the age of 60. One death was attributed to myocardial rupture after a recurrent anterior infarction while another two were suspected of having died from sepsis. No causes were reported for the other three deaths.
L-arginine is potentially harmful to patients recovering from heart attack for a number of reasons such as: (1) L-arginine supplementation may cause an increase in homocysteine production which can lead to poor endothelial function and atherosclerosis; increased generation of reactive oxygen species; and (3) increased activity of the inducible isoform of nitric oxide synthase.
According to the authors of the study, L-arginine “neither alters noninvasive measures of vascular stiffness nor improves left ventricular function. Moreover, the researchers warned that older patients with “diffuse atherosclerosis” may suffer more serious clinical outcomes.
The conclusion of the researchers is that “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.”