Unstable Angina and Other Acute Coronary Syndromes

Patients with coronary artery disease (CAD) present clinically when their disease enters an unstable phase known as an acute coronary syndrome (ACS), in which the cap of a previously stable atheromatous coronary plaque ruptures or erodes, which in turn activates a thrombotic cascade that may lead to coronary artery occlusion, myocardial infarction (MI), cardiogenic shock, and patient death. There are nearly 2 million episodes of ACS in the United States annually; it is the most common reason for hospitalization with CAD and is the leading cause of death in the developed world. ACS patients include those with unstable angina (UA), non–ST segment elevation myocardial infarction (non-STEMI), and ST segment elevation myocardial infarction (STEMI) and patients who die suddenly of an arrhythmia precipitated by coronary occlusion. The distinction among various ACS subgroups reflects varying characteristics of clinical presentation (presence or absence of elevated cardiac biomarkers) and the type of electrocardiographic (ECG) changes manifested on the initial ECG at the time of hospitalization. This chapter focuses on UA and non-STEMI. A graph outlines mortality risks faced by patients with varying degrees of renal insufficiency. An algorithm describes the suggested management of patients admitted with UA or non-STEMI. Tables describe the risk stratification of the patient with chest pain, categories of Killip class, examination findings of a patient with high-risk ACS, diagnosis of MI, causes of troponin elevation other than ischemic heart disease, initial risk stratification of ACS patients, and long-term medical therapies and goals in ACS patients. This review contains 2 highly rendered figures, 11 tables, and 76 references.