What is stable angina?

Stable Angina: Definition and Management

Stable angina is chest pain or discomfort due to myocardial ischemia that occurs predictably with exertion or stress, follows a consistent pattern for at least 6 weeks, and is relieved by rest and/or nitroglycerin within minutes. 1, 2

Clinical Characteristics

Stable angina has three defining features:

• Substernal chest discomfort of characteristic quality and duration
• Provocation by physical exertion or emotional stress
• Relief by rest and/or nitrates within minutes 1

The discomfort is typically described as:

• Located in the chest, near the sternum (may radiate to jaw, arms, back)
• Characterized as pressure, tightness, heaviness, or burning
• Brief duration (usually less than 10 minutes)
• Predictably triggered by specific activities 1

Classification

The Canadian Cardiovascular Society (CCS) classifies angina severity into four grades:

• Class I: Ordinary activity (walking, climbing stairs) doesn't cause angina. Symptoms occur only with strenuous, rapid, or prolonged exertion.
• Class II: Slight limitation of ordinary activity. Angina occurs when walking/climbing stairs rapidly, after meals, in cold weather, under emotional stress, or when walking more than 2 blocks.
• Class III: Marked limitation of ordinary activity. Angina occurs when walking 1-2 blocks or climbing one flight of stairs at normal pace.
• Class IV: Inability to perform any physical activity without discomfort; angina may be present at rest. 1

Differentiating from Other Types of Angina

Stable angina differs from other forms of angina:

• Unstable angina: Occurs at rest, is new-onset with severe symptoms, or represents a significant change in previously stable pattern. It typically lasts longer (>20 minutes), may be associated with ECG changes, and requires urgent medical attention. 2

• Variant (Prinzmetal) angina: Usually occurs spontaneously at rest rather than with exertion, often associated with transient ST-segment elevation. 1

• Microvascular angina: Pain may start after exertion and respond poorly to nitrates. 1

Clinical Significance and Prognosis

Stable angina significantly impacts quality of life by limiting daily activities. Patients with stable angina are at increased risk for:

• Myocardial infarction
• Heart failure
• Stroke
• Cardiovascular death 3

Risk stratification is important to guide management decisions, with annual cardiovascular mortality rates categorized as:

• High risk: >2% annual cardiovascular mortality
• Intermediate risk: 1-2% annual cardiovascular mortality
• Low risk: <1% annual cardiovascular mortality 2

Management Approach

Treatment of stable angina has two primary goals:

1. Reduce morbidity and mortality
2. Relieve symptoms and improve quality of life 4

Pharmacological Management

First-line medications include:

• Beta-blockers: Recommended as initial therapy in the absence of contraindications 4
• Calcium channel blockers: Alternative first-line therapy if beta-blockers are contraindicated or cause unacceptable side effects 4
• Short-acting nitrates: For immediate symptom relief 2

Additional medications:

• Long-acting nitrates: Third-line therapy (require nitrate-free interval to prevent tolerance) 4
• Ranolazine: May be added for symptom control in patients who remain symptomatic despite other antianginal medications 5
• Aspirin: 75-325 mg daily for prevention of cardiovascular events 4
• Statins: For prevention of disease progression 6
• ACE inhibitors: Particularly beneficial in patients with left ventricular dysfunction, hypertension, or diabetes 2

Revascularization

Revascularization (PCI or CABG) should be considered when:

• Symptoms are not adequately controlled with medical therapy
• High-risk coronary anatomy is present (left main disease, three-vessel disease, or proximal LAD stenosis) 2, 4

CABG improves survival in patients with:

• Left main coronary artery disease
• Three-vessel disease
• Two-vessel disease with proximal LAD stenosis 4

Common Pitfalls in Management

1. Failure to distinguish stable from unstable angina: Unstable angina requires urgent evaluation and treatment, while stable angina can be managed in an outpatient setting. 2

2. Inadequate risk factor modification: Aggressive management of risk factors (smoking, hypertension, diabetes, dyslipidemia) is essential for preventing disease progression. 3

3. Inappropriate medication selection: Beta-blockers may be contraindicated in patients with severe bradycardia or advanced heart block; calcium channel blockers may worsen heart failure in patients with reduced ejection fraction. 6

4. Overlooking the need for regular follow-up: Patients with stable angina should be monitored regularly to assess for changes in symptoms, medication effectiveness, and disease progression. 2

By understanding the characteristics and appropriate management of stable angina, healthcare providers can effectively improve symptoms, enhance quality of life, and reduce the risk of adverse cardiovascular outcomes in affected patients.