Thrombolytic therapy for acute myocardial infarction

Thrombolytics are essential first-line agents for management of acute myocardial infarction. T-PA has superior efficacy to streptokinase and anistreplase, with a slightly increased risk of intracerebral hemorrhage in patients over 65. The newer agents, reteplase and tenecteplase, have efficacy equal to t-PA, with similar or lower risk of bleeding, but with improved pharmacologic profiles allowing more convenient bolus administration. Thrombolytic agents offer the greatest benefit when they are given early to patients with larger infarctions or who have a higher risk of dying from their infarction, with the exception of cardiogenic shock. Prior myocardial infarction, diabetes mellitus, stable systemic hypertension, and CPR should not be considered contraindications to thrombolysis. Attempts should be made to reduce acute elevations in blood pressure prior to thrombolytic administration, and mechanical means of establishing reperfusion may be preferable in patients with severe hypertension. Thrombolytic efficacy is unproven for patients with previous coronary artery bypass surgery or cardiogenic shock. Patients greater than age 75 years benefit relatively less than younger patients, although the overall absolute risk reduction is still approximately 10/1,000 lives saved. Elderly patients with larger infarcts, presenting earlier and with few risk factors for thrombolytic complications, will benefit more. For patients presenting later than 12 hr, with smaller infarctions, advanced age, severe uncontrolled hypertension, prior cerebrovascular disease, or with increased risk for thrombolytic induced complications such as bleeding and intracranial hemorrhage, thrombolytic administration should be given with caution, and other options such as direct coronary angioplasty should be considered primary therapy for these patients.