The TIMI risk score is a helpful index to gauge the risk for early mortality in patients presenting with ST-elevation myocardial infarction (Table 8). Overall, the post–myocardial infarction mortality rates are generally low for stable patients who present early for reperfusion therapy but are high for patients admitted in cardiogenic shock.

In patients who underwent direct revascularization, further noninvasive stress testing is indicated only if stenosis of intermediate severity (luminal diameter narrowing of 50% to 70%) is present in a nonculprit coronary artery or if myocardial viability testing is required before further coronary revascularization.

However, in patients successfully treated with thrombolysis, further evaluation is required to assess for residual myocardial ischemia. Coronary angiography is appropriate in patients with recurrent myocardial ischemia, hemodynamic instability, ventricular tachycardia, clinical heart failure, ejection fraction of 40% or less, or post–myocardial infarction mechanical complications (40). Predischarge noninvasive symptom-limited stress testing is appropriate in patients with an uncomplicated course after thombolytic therapy.

Antiarrhythmic therapy is not routinely indicated after ST-elevation myocardial infarction. The occurrence of asymptomatic nonsustained ventricular tachycardia within 48 hours of myocardial infarction does not have long-term prognostic significance. However, asymptomatic nonsustained ventricular tachycardia more than 48 hours after myocardial infarction or symptomatic ventricular arrhythmias, particularly in patients with an ejection fraction of 35% or less, identifies patients at potentially higher risk for sudden cardiac death and generally prompts consideration of an implantable cardioverter-defibrillator (see Arrhythmias).

Patients with recurrent ischemic-type chest discomfort after initial reperfusion therapy for ST-elevation myocardial infarction should receive medical therapy with nitrates and β-blockers to decrease myocardial oxygen demand and reduce ischemia. Intravenous anticoagulation should be initiated if not already accomplished. In addition, urgent cardiac catheterization and revascularization typically are needed. Insertion of an intra-aortic balloon pump should be considered with refractory symptoms or as a bridge to surgical revascularization. It is reasonable to (re)administer fibrinolytic therapy to patients with recurrent ST-segment elevation and ischemic-type chest discomfort who are not considered candidates for revascularization or for whom coronary angiography and PCI cannot be rapidly implemented (ideally, less than 60 minutes from the onset of recurrent discomfort). Streptokinase should not be readministered to treat recurrent ischemia/infarction more than 5 days after previously treated acute ST-elevation myocardial infarction because of the potential for increased intracranial hemorrhage or an allergic reaction.

The use of warfarin after ST-elevation myocardial infarction is complex. The addition of warfarin to the antiplatelet agents commonly used leads to an increased risk of bleeding. A strategy for the use of warfarin is provided in the ACC/AHA guidelines for the management of ST-elevation myocardial infarction (Figure 4). (Open the interactive tutorial.) Patients in whom a stent has been implanted should receive aspirin and clopidogrel, whereas warfarin is reserved for patients with other indications for chronic anticoagulation, with a INR goal of 2.0 to 3.0. In post–ST-elevation myocardial infarction patients without a stent and without other indications for anticoagulation, warfarin can be used as an alternative or in addition to aspirin. Warfarin should be strongly considered for post–ST-elevation myocardial infarction patients with left ventricular dysfunction and extensive regional wall motion abnormalities with or without chronic heart failure because of a higher risk of intracardiac thrombus formation and subsequent systemic embolism.

40. Scanlon PJ, Faxon DP, Audet AM, Carabello B, Dehmer GJ, Eagle KA, et al. ACC/AHA guidelines for coronary angiography. A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Committee on Coronary Angiography). Developed in collaboration with the Society for Cardiac Angiography and Interventions. J Am Coll Cardiol. 1999;33:1756-824. [PMID: 10334456]

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