Alternative interventions are available for patients in whom thrombolytic therapy is inappropriate after an acute myocardial infarction. Administration of a beta blocker within the first 24 hours of the patient's admission to the coronary care unit can reduce overall morbidity and mortality within the first 7 days by about 15%. Maintenance therapy with an oral beta blocker can reduce mortality within the succeeding 3 years by about 25%. Esmolol, a unique cardioselective beta 1-adrenergic receptor blocker with a half-life of 9 minutes, can enable some patients with relative contraindications to beta blockers to nevertheless benefit from early beta-blocking therapy. It also is useful in screening patients for subsequent therapy with beta blockers. Those who tolerate the esmolol infusion can be given a long-acting beta blocker. For patients who exhibit intolerance to esmolol, the infusion can be terminated with rapid return to baseline hemodynamics.