Management of acute non-Q-wave myocardial infarction: role of prophylactic pharmacotherapy and indications for predischarge coronary arteriography.

Non-Q-wave myocardial infarction (MI) differs from Q-wave MI in three important respects: (1) smaller infarct size possibly due to early reperfusion as a result of spontaneous thrombolysis, relief of spasm, or both; (2) more frequent patency of the infarct-related artery; and (3) a larger residual mass of viable but jeopardized myocardium within the perfusion zone of the infarct-related vessel. Left ventricular function, unless impaired by previous MI, is generally better. The prognosis is worse after the acute phase, when residual ischemia is present, and reinfarction rates during hospitalization and in the subsequent year of follow-up are higher. Obviously, since myocardial ischemia is potentially reversible, its presence should be energetically sought in all patients with recognized non-Q-wave MI. Based on our current understanding and available data, the following guidelines for the management of non-Q-wave MI patients can be recommended: (1) antiplatelet therapy along with diltiazem should be administered to patients as soon as the diagnosis is established, unless contraindications exist; (2) patients who develop early recurrent ischemia on therapy, that is, angina with associated ST-T-wave changes, should undergo prompt cardiac catheterization and myocardial revascularization; (3) patients with entirely uncomplicated hospital courses who are asymptomatic should undergo exercise stress testing, preferably in conjunction with thallium-201 imaging, before hospital discharge. Only those with evidence of significant residual ischemia need cardiac catheterization and myocardial revascularization.