Indications, timing, and optimal technique for diagnostic angiography and angioplasty in acute myocardial infarction. Emergency cardiac catheterization and coronary angioplasty for acute myocardial infarction (MI) have a continuing role in the thrombolytic era. Although thrombolytic therapy has revolutionized the treatment of MI, it has significant shortcomings: about 75% of patients with acute MI cannot be treated with thrombolytic agents, 25% of treated patients will have persistent occlusion of the infarct-related artery, 70% will have a residual stenosis greater than or equal to 70%, and 20% of treated patients will experience reocclusion. Cardiac catheterization identifies the coronary anatomy for mechanical revascularization and allows the unstable patient to receive special therapy, such as intra-aortic balloon pumping. Many large clinical studies have evaluated approaches to coronary angioplasty for acute MI. Deferred angioplasty has indisputable advantages over immediate routine angioplasty. Direct angioplasty without concomitant thrombolytic therapy has acceptable success and complication rates, so that it can be considered the treatment of choice for acute MI in centers with an angioplasty program if thrombolytic therapy is contraindicated. Patients at very low risk may not require cardiac catheterization routinely before discharge, since their good prognosis cannot be improved by invasive evaluation and intervention. Emergency surgical revascularization is indicated in a very small percentage of cases. 