Contemporary Diagnosis and Management of Unstable Angina

Abstract

Unstable angina (UA) is one of the acute coronary syndromes, a group of conditions that also includes non-ST elevation myocardial infarction (MI) and ST elevation MI. The underlying pathogenic substrate of all these entities is the unstable coronary plaque with an overlying intracoronary thrombus. Initial management for the patient with suspected UA includes a resting electrocardiogram and oral administration of aspirin. ST-segment elevation indicates acute MI with the need for urgent reperfusion therapy. Patients without ST-segment elevation commonly have a mixture of UA and non-ST elevation MI; initial management is similar with assessment of near-term risk of MI or death as the next step. Features of UA indicating high risk include persistent ST-segment depression, persistent ischemic pain, elevated troponin level, or features of heart failure. Such patients undergo intensive medical therapy with heparin (unfractionated or low-molecular-weight), beta-blockade, and IIb/IIa antiplatelet agents, usually followed by coronary angiography and percutaneous intervention. The timing of intervention depends on the patient's response to therapy. Intermediate- or low-risk patients (including those presenting to the emergency department) can be managed with a chest pain unit strategy, and those with normal results on serial electrocardiograms, cardiac marker studies, and functional testing can be safely discharged home. Others are admitted for elective angiography, intensive medical therapy, or both. Assessment of coronary risk factors and their modification is an important component of long-term therapy for both high-risk and low-risk patients with UA, as well as those determined to have had non-ST elevation MI.