Intravenous nitroglycerin in acute myocardial infarction.

Until recently, the use of nitroglycerin in patients with acute myocardial infarction has been contraindicated primarily because of possible hypotension or tachycardia which, with sublingual or oral preparations, would be difficult to control. The introduction of intravenous nitroglycerin and its use during experimentally induced infarction paved the way for its use in patients with acute myocardial ischemia. It was shown that nitroglycerin, administered intravenously during experimentally induced coronary artery occlusion, redistributed flow to the subendocardium of the ischemic area while it maintained flow to the normal areas and was associated with decreased S-T segment elevation. Preliminary studies in patients with acute infarction have confirmed the beneficial effect of intravenous nitroglycerin on S-T segment elevation, and a subsequent study in 31 patients with acute infarction showed a decrease in infarct size with improved hemodynamics. In a more recent randomized prospective study in 85 patients with acute myocardial infarction, we found that intravenous nitroglycerin was associated with a decrease in infarct size in patients with inferior infarction (36 percent reduction, p less than 0.05) but that it had no effect on infarct size in patients with anterior infarction. Whether or not nitroglycerin should be used routinely for reduction of infarct size remains to be determined, but results indicate that it is effective and safe for the treatment of cardiac failure in patients with acute myocardial infarction.