- The cause of an acute coronary syndrome (ACS) is the erosion or rupture of an atherosclerotic plaque with subsequent platelet adherence, activation, aggregation, and activation of the clotting cascade. Ultimately, a clot forms and is composed of fibrin and platelets.
- The American Heart Association (AHA) and the American College of Cardiology (ACC) recommend strategies or guidelines for ACS patient care for ST-segment elevation (STE) myocardial infarction (MI) and unstable angina, non-ST-segment elevation (NSTE) MI, also termed NSTE ACS.
- Patients with ischemic chest discomfort and suspected ACS are risk stratified based on a 12-lead electrocardiogram (ECG), past medical history, signs and symptoms, and results of creatine kinase myocardial band (CK-MB) and troponinbiochemical marker tests.
- The diagnosis of MI is confirmed based on the results of the CK-MB and troponin tests.
- Early reperfusion therapy with either primary percutaneous coronary intervention (PCI) or administration of a fibrinolytic agent is the recommended therapy for patients presenting with STE MI.
- High-risk patients with NSTE ACS should undergo early coronary angiography and revascularization with either PCI or coronary artery bypass graft (CABG) surgery.
- In addition to reperfusion therapy, additional pharmacotherapy that all patients with STE MI and without contraindications should receive within the first day of hospitalization and preferably in the emergency department are intranasal oxygen (if oxygen saturation is low), aspirin, a thienopyridine (agent and timing dependent on reperfusion strategy), sublingual (SL) nitroglycerin (NTG), and anticoagulation with either bivalirudin, unfractionated heparin (UFH), or enoxaparin (agent dependent on reperfusion strategy). A glycoprotein IIb/IIIa inhibitor should be administered with UFH for patients undergoing primary PCI. Intravenous (IV) β-blockers and NTG should be given to select patients.
- In the absence of contraindications, all patients with NSTE ACS should be treated in the emergency department with intranasal oxygen (if oxygen saturation is low), aspirin, SL NTG, and an anticoagulant, either UFH, enoxaparin, fondaparinux, or bivalirudin. High-risk patients should proceed to early coronary angiography and may additionally receive a glycoprotein IIb/IIIa inhibitor. Clopidogrel or prasugrel [agent and timing dependent on selection of an interventional (PCI) or medical management strategy] should be administered to all patients. Intravenous β-blockers and nitroglycerin should be given to select patients.
- Following MI, all patients, in the absence of contraindications, should receive indefinite therapy with aspirin, a β-blocker (started within 24 hours of hospital arrival), and an angiotensin-converting enzyme (ACE) inhibitor for secondary prevention of death, stroke, and recurrent infarction. Most patients will receive a statin to reduce low-density lipoprotein cholesterol to less than 100 mg/dL and ideally less than 70 mg/dL. Clopidogrel or prasugrel should be continued for at least 12 months for patients undergoing PCI, and clopidogrel should be continued for at least 14 days in patients with STE MI who either did not receive reperfusion therapy or received fibrinolytic therapy without PCI and who are at low risk of bleeding. Anticoagulation with warfarin should be considered for patients at high risk of death, reinfarction, or stroke.
Upon completion of the chapter, the reader will ...