Acute coronary syndromes (ACS) is a term used to describe a group of conditions resulting from acute myocardial ischemia (insufficient blood flow to heart muscle) and ranging from unstable angina (increasing, unpredictable chest pain) to myocardial infarction (heart attack). The conditions are related to varying degrees of narrowing or blockage of single or multiple coronary arteries that provide blood, oxygen, and nutrients to the heart. This life-threatening disorder is a major cause of emergency medical care and hospitalization. Coronary artery disease (CAD) remains the leading cause of death in the United States. The January 6, 2010, issue of JAMA includes an article about treatment decisions in acute coronary syndromes. This Patient Page is based on one previously published in the July 2, 2008, issue of JAMA.