What is the diagnosis and treatment for unstable angina (acute coronary syndrome)?

From the Guidelines

Unstable angina requires immediate medical attention and treatment typically involves hospitalization for close monitoring, including antiplatelet therapy, anticoagulation, and anti-ischemic medications. The management of unstable angina involves a combination of pharmacological and interventional strategies.

• The initial management includes the administration of aspirin, clopidogrel, and low molecular weight heparin, as well as the use of beta-blockers and nitroglycerin to control symptoms and reduce ischemia 1.
• Patients with high-risk features, such as recurrent ischemia, elevated troponin levels, or hemodynamic instability, should undergo coronary angiography as soon as possible, with a view to revascularization by percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) 1.
• The choice of revascularization strategy depends on the extent and characteristics of the coronary artery disease, as well as the presence of other comorbidities, such as diabetes or left ventricular dysfunction 1.
• In patients with single-vessel disease, PCI is generally the preferred approach, while in those with multi-vessel disease, CABG may be more appropriate, particularly if there is significant left ventricular dysfunction or other high-risk features 1.
• The use of platelet glycoprotein IIb/IIIa inhibitors, such as abciximab or tirofiban, may be beneficial in high-risk patients undergoing PCI, but is not recommended for lower-risk patients who do not undergo PCI 1.
• An intensive program of secondary prevention, including lifestyle modification, risk factor management, and medical therapy, is essential to reduce the risk of further ischemic events and improve long-term outcomes 1. Key considerations in the management of unstable angina include:
• Early risk stratification using clinical criteria and biomarkers to identify high-risk patients who require more aggressive management
• The use of evidence-based therapies, such as antiplatelet agents, beta-blockers, and statins, to reduce ischemia and improve outcomes
• The selection of an appropriate revascularization strategy based on the extent and characteristics of the coronary artery disease, as well as the presence of other comorbidities
• The importance of secondary prevention and lifestyle modification to reduce the risk of further ischemic events and improve long-term outcomes.

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 Key Points:

• Clopidogrel is indicated for unstable angina to reduce the rate of myocardial infarction and stroke.
• It should be administered in conjunction with aspirin.
• The recommended dose is a single 300 mg oral loading dose, followed by 75 mg once daily. 2

From the Research

Definition and Diagnosis of Unstable Angina

• Unstable angina (UA) and non-ST-segment elevation myocardial infarction (NSTEMI) are acute coronary syndromes with potentially high morbidity and mortality 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/NSTEMI and the overall assessment of patient prognosis and risk 3.

Treatment and Management of Unstable Angina

• Standard therapy for UA/NSTEMI has commonly included oxygen, aspirin, nitrates, morphine, beta-blockers, and heparin 3, 4.
• Low molecular weight heparins have been shown to be an effective alternative to unfractionated heparin in the treatment of unstable angina 3, 5.
• Pharmaceutical agents for UA/NSTEMI may be broadly grouped into one of three categories: anti-ischemic, anti-platelet, and anti-thrombotic agents 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.

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 6.
• Significant predictors of "failing" medical therapy include ST segment depression, accelerated angina, nitrate use, exertional angina, and cardiac troponin I levels 6.
• 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 6.

Evolution of Treatment Strategies

• New treatments are rapidly being added to the growing arsenal of management options for unstable angina, and clinicians are constantly challenged with incorporating complex new information and guidelines into their practices in a timely fashion 3.
• Major advances in invasive techniques and devices over the last decade include revascularization with percutaneous coronary intervention and drug-eluting intracoronary stents 3.
• Strong interest exists in studying the potential benefits and risks associated with an early invasive therapeutic strategy rather than an aggressive medical regimen for patients with UA/NSTEMI 3.