Definition of Stable Angina
Stable angina is a clinical syndrome characterized by discomfort in the chest, jaw, shoulder, back, or arms that is typically elicited by exertion or emotional stress and relieved by rest or nitroglycerin within minutes, attributed to myocardial ischemia. 1
Core Diagnostic Criteria
To diagnose typical (stable) angina, all three of the following characteristics must be present 2:
- Substernal chest discomfort of characteristic quality and duration (pressure, tightness, heaviness, strangling, constricting, or burning sensation)
- Provoked by exertion or emotional stress
- Relieved by rest and/or nitrates within minutes
Atypical angina meets only two of these three characteristics, while non-anginal chest pain meets one or none 2.
Key Clinical Features
Location and Character
The discomfort is usually located near the sternum but may radiate to:
- Epigastrium to lower jaw or teeth
- Between shoulder blades
- Either arm to wrist and fingers
- Less typically, the epigastric area alone 1
Duration and Pattern
- Brief duration: typically not more than 10 minutes, often even less 1
- Predictable triggers: worsens with increased exertion (walking uphill, against wind), after heavy meals, or first thing in the morning 2
- Rapid relief: symptoms disappear within minutes when causal factors abate 1
- May exhibit "walk-through angina" (improves with continued exercise) or "warm-up angina" (better on second exertion) 2
Associated Symptoms
May include:
- Shortness of breath
- Fatigue or faintness
- Nausea, burping
- Restlessness or sense of impending doom 1
Pathophysiology
Stable angina results from myocardial ischemia due to an imbalance between oxygen supply and demand 3, 4. The term is confined to cases attributable to myocardial ischemia, though similar symptoms can arise from esophageal, pulmonary, or chest wall disorders 1.
The most common cause is atherosclerotic coronary artery disease, though myocardial ischemia may also result from hypertrophic or dilated cardiomyopathy, aortic stenosis, or microvascular dysfunction in the absence of obstructive coronary disease 1, 2.
Distinguishing from Unstable Angina
Critical distinction: Stable angina must be differentiated from unstable angina, which carries significantly higher short-term risk. Unstable angina presents as:
- Rest angina lasting up to 20 minutes
- Rapidly increasing crescendo pattern over ≤4 weeks
- New onset severe angina with marked limitation within 2 months 1
Severity Classification
The Canadian Cardiovascular Society Classification grades stable angina severity 1, 2:
- Class I: Ordinary activity does not cause angina; occurs only with strenuous/rapid/prolonged exertion
- Class II: Slight limitation of ordinary activity (angina walking >2 blocks, climbing >1 flight of stairs rapidly, after meals, in cold/wind, or under stress)
- Class III: Marked limitation (angina walking 1-2 blocks or climbing 1 flight of stairs at normal pace)
- Class IV: Inability to perform any physical activity without discomfort; angina may occur at rest
Clinical Pitfalls
Important caveats:
- The severity of discomfort does not correlate with the severity of underlying coronary disease 1
- Non-anginal pain typically involves only a small portion of the left hemithorax, lasts hours to days, is not relieved by nitroglycerin (except esophageal spasm), and may be provoked by palpation 1
- The angina threshold may vary considerably day-to-day and even within the same day 2