From the Guidelines
Unstable angina requires immediate medical attention and hospitalization for close monitoring, with treatment typically involving antiplatelet therapy, anticoagulation, and potential revascularization through percutaneous coronary intervention or coronary artery bypass grafting. The management of unstable angina involves a comprehensive approach, including:
- Antiplatelet therapy with aspirin and a P2Y12 inhibitor such as clopidogrel 1
- Anticoagulation with heparin or low molecular weight heparin 1
- Additional medications such as beta-blockers, high-intensity statins, and nitroglycerin for symptom relief
- Supplemental oxygen if oxygen saturation is low
- Cardiac catheterization to assess coronary anatomy and potentially undergo revascularization
The decision to undergo revascularization is based on the extent and characteristics of the coronary lesions, with percutaneous intervention being the first choice for single-vessel disease and coronary artery bypass grafting being the recommended procedure for left main- or triple-vessel disease 1. The use of platelet glycoprotein IIb/IIIa antagonists is indicated in high-risk patients likely to undergo percutaneous coronary intervention 1. An intensive program of secondary prevention is mandatory and should be begun before hospital discharge.
In patients with suitable lesions for percutaneous coronary intervention, clopidogrel should be administered, while in patients planned for coronary artery bypass grafting, clopidogrel should be stopped about 5 days before operation 1. The management of unstable angina should be guided by the most recent and highest quality evidence, with a focus on reducing morbidity, mortality, and improving quality of life.
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
- Indication: Clopidogrel is indicated for patients with unstable angina to reduce the rate of myocardial infarction and stroke.
- Dosage: The recommended dosage is a single 300 mg oral loading dose, followed by 75 mg once daily.
- Key consideration: Clopidogrel should be administered in conjunction with aspirin 2.
From the Research
Definition and Diagnosis of Unstable Angina
- Unstable angina (UA) is a clinical syndrome characterized by increased rate and severity of angina pectoris attacks, sometimes accompanied by ECG changes similar to those seen in coronary insufficiency 3.
- Diagnosis of unstable angina is complicated by the dynamic range of presentations, which can vary between atypical chest pain and acute myocardial infarction 4.
- Integration of information from the history, physical exam, electrocardiogram, and cardiac biomarkers is used to formulate both the diagnosis of UA and the overall assessment of patient prognosis and risk 5.
Treatment and Management of Unstable Angina
- Standard therapy for UA has commonly included oxygen, aspirin, nitrates, morphine, beta-blockers, and heparin 5, 6.
- Pharmaceutical agents for UA may be broadly grouped into one of three categories: anti-ischemic, anti-platelet, and anti-thrombotic agents 5.
- Low-molecular-weight heparins have been shown to be an effective alternative to unfractionated heparin in the treatment of UA 5, 6.
- Potent new anti-platelet agents, including inhibitors of platelet adenosine diphosphate and glycoprotein IIb/IIIa receptors, play important, expanding roles in the management of UA 5, 6.
Predicting Failure of Medical Therapy
- A clinical decision rule has been developed 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.
- A risk score can be used to predict which patients will subsequently fail medical therapy and undergo cardiac catheterization, with higher scores indicating a higher probability of failure 7.