Use of nitrates in patients with acute myocardial infarction

The use of nitrates in treating acute myocardial infarction is reviewed; proposed mechanisms of action and pertinent pathophysiology are discussed. Oral and sublingual nitrates were first tested in acute myocardial infarction patients with mixed results. Later studies with sublingual nitroglycerin followed by phenylephrine infusion indicated that nitrates were effective in limiting myocardial ischemia and necrosis. I.V. nitroglycerin was then studied; beneficial results were documented by quantifying ECG changes and visualizing the areas of myocardial necrosis with radioisotopes. Mortality was also reduced in nitrate-treated patients. Patients who developed left ventricular failure after acute myocardial infarction benefitted the most from nitrate therapy. The preferred route of nitroglycerin administration is intravenous infusion. The dose is initially 5 micrograms/min and is increased by 5-10 micrograms/min every 5-10 minutes until mean arterial pressure is reduced 10-20% or pulmonary capillary wedge pressure is reduced to 15 mm Hg. Final infusion rates average 40-60 micrograms/min. Nitrates appear to have a role in reducing morbidity and mortality from acute myocardial infarction.