Acute coronary syndromes: pathogenesis, acute diagnosis with risk stratification, and treatment.

Acute ischemic chest pain at rest consistent with unstable angina or non-ST-elevation myocardial infarction is a common problem that may cause death or recurrent myocardial infarction within 30 days unless identified and risk stratified acutely. The latter may be done within 15 minutes by the history, physical exam, and electrocardiogram, and is aided by the measurement of troponin T/I. According to the Agency for Health Care Policy and Research guidelines, low-risk patients can be discharged home and rechecked within 72 hours. Intermediate-risk patients with no ST-segment changes with continuous monitoring and no elevation of troponin should undergo exercise stress testing by electrocardiogram (or nuclear or echocardiographic evaluation if electrocardiogram is non-analyzable). Patients with a negative stress test are low risk (no death or myocardial infarction at 30 days or 6 months) and can be discharged home. Patients with a positive test or who are at high risk according to the Agency for Health Care Policy and Research guidelines should undergo acute invasive testing for possible revascularization. Aspirin and low molecular weight heparin or unfractionated heparin, along with anti-ischemia therapy, is indicated in intermediate- or high-risk patients. The addition of clopidogrel is indicated in these patients, except in those who are potential candidates for coronary artery bypass graft. Platelet glycoprotein IIb/IIIa inhibitors are indicated in high-risk patients likely to undergo percutaneous coronary intervention, should be started early if recurrent ischemia occurs, but are not indicated in lower-risk patients who do not require percutaneous coronary intervention. Intensive secondary prevention should be started before dismissal.