From the Guidelines
Unstable angina is a medical emergency requiring immediate hospitalization and treatment with a focus on antiplatelet and anticoagulant therapy to prevent further clot formation and reduce myocardial oxygen demand. The diagnosis of unstable angina involves identifying patients with new-onset chest pain at rest, worsening or more frequent angina, or angina that occurs with less exertion than usual.
Immediate Management
The immediate management involves administering aspirin (325 mg chewed) and sublingual nitroglycerin (0.4 mg every 5 minutes, up to 3 doses) if not contraindicated, as well as oxygen therapy if saturation is below 90% 1.
Antiplatelet and Anticoagulant Therapy
The cornerstone of treatment is antiplatelet and anticoagulant therapy, starting with dual antiplatelet therapy: aspirin 81 mg daily indefinitely, plus a P2Y12 inhibitor such as clopidogrel (loading dose 300-600 mg, then 75 mg daily) or ticagrelor (loading dose 180 mg, then 90 mg twice daily) 1.
Additional Medications
Additional medications include beta-blockers (e.g., metoprolol 25-50 mg orally twice daily) to reduce myocardial oxygen demand, and high-intensity statins (e.g., atorvastatin 80 mg daily) to stabilize plaques 1.
Long-term Management
Long-term management involves risk factor modification, including smoking cessation, blood pressure control, diabetes management, and lifestyle changes, as well as cardiac rehabilitation and regular follow-up 1.
Rationale for Treatment
The rationale for this aggressive treatment is based on the pathophysiology of unstable angina, which involves plaque rupture and subsequent thrombus formation, and is supported by the most recent guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation 1. Some key points to consider in the management of unstable angina include:
- Early risk stratification using clinical criteria and biomarkers
- The use of low-molecular-weight heparin (LMWH) such as enoxaparin as an alternative to unfractionated heparin (UFH) 1
- The importance of an early invasive strategy with catheterization followed by revascularization in patients at high and intermediate risk 1
- The use of platelet glycoprotein (GP) IIb/IIIa antagonists in high-risk patients likely to undergo percutaneous coronary intervention (PCI) 1
- The consideration of coronary artery bypass grafting (CABG) in patients with left main or triple-vessel disease, particularly in those with left ventricular dysfunction 1.
From the FDA Drug Label
Clopidogrel tablets are indicated to reduce the rate of myocardial infarction (MI) and stroke in patients with non–ST-segment elevation ACS (unstable angina [UA]/non–ST-elevation myocardial infarction [NSTEMI]), including patients who are to be managed medically and those who are to be managed with coronary revascularization Clopidogrel tablets should be administered in conjunction with aspirin.
The diagnosis of unstable angina, a type of Acute Coronary Syndrome (ACS), is based on clinical presentation and diagnostic tests. The treatment for unstable angina includes:
- Antiplatelet therapy: Clopidogrel tablets, in conjunction with aspirin, to reduce the rate of myocardial infarction and stroke.
- Medical management: Patients with unstable angina may be managed medically.
- Coronary revascularization: Some patients with unstable angina may require coronary revascularization. Key considerations:
- Dosage: A single 300 mg oral loading dose of clopidogrel, followed by 75 mg once daily.
- Contraindications: Active bleeding, hypersensitivity to clopidogrel or any component of the product 2 2.
From the Research
Diagnosis of Unstable Angina (Acute Coronary Syndrome)
- The diagnosis of unstable angina involves the integration of information from the history, physical exam, electrocardiogram, and cardiac biomarkers 3
- Patients suspected of having unstable angina but thought to be at low risk can be discharged after clinical evaluation if further outpatient evaluation within 72 hours is scheduled 4
- Assessment of prognosis by noninvasive testing often aids in selection of appropriate therapy 4
Treatment of Unstable Angina (Acute Coronary Syndrome)
- The goals of treatment are to stabilize the patient's condition and prevent progression to acute myocardial infarction or death 4
- Pharmaceutical agents for unstable angina may be broadly grouped into one of three categories: anti-ischemic, anti-platelet, and anti-thrombotic agents 3
- Standard therapy for unstable angina has commonly included oxygen, aspirin, nitrates, morphine, beta-blockers, and heparin 3
- Potent new anti-platelet agents, including inhibitors of platelet adenosine diphosphate and glycoprotein IIb/IIIa receptors, play important, expanding roles in the management of these syndromes 3
- Low-molecular-weight heparins have been shown to be an effective alternative to unfractionated heparin in their treatment 3
- Coronary angiography is appropriate in patients judged to be at high risk for cardiac complications on the basis of their clinical course or results of non-invasive testing 4
- Coronary artery bypass grafting should be recommended in almost all patients with left main coronary artery disease and many with multivessel disease, especially those with left ventricular dysfunction 4
- Percutaneous transluminal coronary angioplasty is also effective in selected patients 4, 5
Risk Stratification and Management
- Early diagnosis and risk stratification of patients with unstable angina enable the physician to initiate timely, appropriate treatment 3
- Decisions must be made about the use of coronary angiography and coronary revascularization in patients hospitalized with unstable angina 6
- A clinical decision rule can be used to predict which patients with unstable angina or non-Q-wave myocardial infarction are likely to "fail" medical therapy and ultimately require cardiac catheterization within 6 weeks of presentation 7
- Significant predictors of "failing" medical therapy include ST segment depression, accelerated angina, nitrate use, exertional angina, and cardiac troponin I levels 7