What is stable angina?

What is Stable Angina

Stable angina is substernal chest discomfort that occurs predictably with exertion or emotional stress, lasts less than 10 minutes, and is relieved by rest or nitroglycerin within minutes—representing reversible myocardial ischemia due to coronary artery disease. 1

Clinical Characteristics

Classic Presentation

• Location: Substernal chest area, but may radiate to the epigastrium, jaw, teeth, between shoulder blades, or either arm to the wrist and fingers 1
• Quality: Described as pressure, tightness, heaviness, strangling, constricting, or burning—many patients report "discomfort" rather than frank "pain" 1
• Duration: Brief episodes lasting no more than 10 minutes, typically just a few minutes or less (chest pain lasting only seconds is unlikely to be angina) 1
• Precipitating factors: Exertion (walking uphill, climbing stairs, cold weather, heavy meals, morning hours), emotional stress 1
• Relieving factors: Rest and sublingual/buccal nitrates provide rapid relief within minutes 1

Associated Symptoms

• Shortness of breath may accompany or be the sole manifestation of stable angina 1
• Less specific symptoms include fatigue, faintness, nausea, burning sensation, restlessness, or sense of impending doom 1

Diagnostic Criteria for Typical Angina

All three of the following must be present 1:

• Substernal chest discomfort of characteristic quality and duration
• Provoked by exertion or emotional stress
• Relieved by rest and/or nitrates within minutes

Atypical angina meets only two of these three characteristics 1

Severity Classification

The Canadian Cardiovascular Society (CCS) grading system stratifies functional impairment 1:

• Class I: Ordinary activity (walking, climbing stairs) does not cause angina; symptoms only with strenuous, rapid, or prolonged exertion 1
• Class II: Slight limitation—angina when walking rapidly, climbing stairs quickly, walking uphill, after meals, in cold/wind, under emotional stress, or climbing more than one flight of stairs 1
• Class III: Marked limitation—angina when walking one to two blocks (100-200 meters) on level ground or climbing one flight of stairs at normal pace 1
• Class IV: Inability to perform any physical activity without discomfort; angina may occur at rest 1

Distinguishing Features from Unstable Angina

Critical distinction: Stable angina has been present for at least 4 weeks without change in frequency or pattern, whereas unstable angina presents with symptoms at rest lasting ≥20 minutes, new-onset severe symptoms (CCS III-IV), or recent acceleration in severity 1, 2

Red Flags for Unstable Angina (Requiring Immediate Hospitalization)

• Rest angina lasting up to 20 minutes 1, 2
• Rapidly increasing crescendo pattern over less than 4 weeks 1
• New onset severe angina with marked limitation within 2 months 1

Atypical Presentations

Variant (Prinzmetal) Angina

• Occurs spontaneously at rest without physical exertion 1
• Pain starts at low intensity, slowly intensifies, remains maximal for up to 15 minutes, then slowly decreases 1
• Frequently associated with transient ST-segment elevation 1
• This pattern should alert clinicians to possible coronary vasospasm 1

Microvascular Angina

• Pain of anginal location and quality triggered by exertion but occurs some time after exertion 1
• May be poorly responsive to nitrates 1
• Due to occlusion of smaller coronary arteries 1

Physical Examination Findings

There are no specific physical signs of stable angina 1. However:

• During or immediately after ischemic episodes, a third or fourth heart sound may be audible 1
• Mitral insufficiency may become apparent during ischemia 1
• These signs are elusive and non-specific 1

Common Pitfalls

• Walk-through angina: Symptoms may paradoxically decrease with continued exercise 1
• Warm-up angina: Symptoms improve on second exertion 1
• Variable threshold: The angina threshold may vary considerably from day to day and even during the same day 1
• Non-cardiac mimics: If chest pain is reproducible by palpation, stable coronary artery disease is less likely 1
• Non-anginal pain: Involves only small portion of left hemithorax, lasts hours to days, not relieved by nitroglycerin (except esophageal spasm), and may be provoked by palpation 1