Stable angina is a classic symptom of coronary artery disease (CAD), often considered a warning sign of underlying myocardial ischemia. It is characterized by chest pain that occurs with physical exertion or emotional stress and is relieved by rest or medication. For clinicians, students, and patients alike, recognizing the hallmark features of stable angina is crucial for timely diagnosis and management.
To aid in recall and rapid recognition, the mnemonic “6S” offers an intuitive and comprehensive guide to understanding the clinical profile of stable angina.
What Is Stable Angina?
Stable angina pectoris refers to predictable chest pain that occurs when myocardial oxygen demand exceeds supply, usually during physical or emotional stress. It typically resolves with rest or the use of nitrates.
Unlike unstable angina or myocardial infarction, stable angina:
- Does not occur at rest
- Is not associated with acute plaque rupture
- Is more predictable and manageable
Pathophysiology of Stable Angina
Stable angina results from myocardial ischemia, typically due to atherosclerotic narrowing of coronary arteries.
Mechanism:
- Coronary artery lumen narrowed by atherosclerotic plaque
- During stress or exertion, the oxygen demand of the heart increases
- The compromised artery cannot supply sufficient oxygen
- Anaerobic metabolism and lactic acid accumulation trigger chest pain
Reversibility: The ischemia in stable angina is transient and does not cause permanent myocardial damage, distinguishing it from infarction.
Mnemonic: “6S” of Stable Angina
This creative mnemonic captures the six most characteristic features of stable angina:
- S – Sudden Onset
- S – Substernal Pain
- S – Spread to Arm
- S – Squeezing in Nature
- S – Short Duration
- S – Sublingual GTN Relieves Pain
Let's unpack each "S" in detail:
1. Sudden Onset
Description:
The chest pain in stable angina begins suddenly, usually triggered by:
- Physical exertion (walking, climbing stairs)
- Emotional stress
- Cold exposure
- Heavy meals
Clue for Diagnosis:
The predictability of pain with specific triggers is a key feature distinguishing stable from unstable angina.
Why it matters:
Sudden onset with exertion signals ischemia — prompting the need for risk assessment and therapy initiation.
2. Substernal Pain
Location:
Pain is typically felt behind the sternum (breastbone), in the central chest.
Patient Description:
- "Pressure," "tightness," "heaviness," or "burning" in the chest
- May mistakenly be described as heartburn
Diagnostic Importance:
Substernal location is part of the typical angina triad along with exertional onset and relief with rest.
3. Spread to Arm
Radiation Pattern:
Pain often radiates to:
- Left arm (most common)
- Neck or jaw
- Back
- Occasionally the right arm or epigastrium
Clinical Insight:
Pain radiation reinforces the diagnosis and helps differentiate angina from non-cardiac causes like musculoskeletal chest pain.
4. Squeezing in Nature
Quality of Pain:
Patients often describe the discomfort as:
- Squeezing
- Pressing
- Constricting
- Like a “tight band” around the chest
Contrast with:
- Sharp, stabbing, pleuritic pain — suggestive of pericarditis or pulmonary embolism
- Positional pain — suggestive of musculoskeletal issues
5. Short in Duration
Time Frame:
Typically lasts for 2–10 minutes and resolves with rest or medication.
Not Characteristic Of:
- Pain lasting >20 minutes → suspect unstable angina or myocardial infarction
- Pain <1 minute → likely non-cardiac
Significance:
The short duration underscores that myocardial damage has not yet occurred — making this a window of opportunity for intervention.
6. Sublingual GTN ↓ Pain
GTN (Glyceryl Trinitrate):
- A vasodilator that increases coronary blood flow and reduces preload
- Commonly taken sublingually during anginal episodes
Response in Stable Angina:
- Rapid relief of pain within 1–3 minutes is typical
Clinical Implication:
- Positive response to GTN helps confirm angina diagnosis
- Failure to respond may point to other pathologies or unstable angina
Summary Table: 6S Mnemonic for Stable Angina
| S # | Feature | Explanation |
|---|---|---|
| 1 | Sudden Onset | Triggered by exertion, emotional stress |
| 2 | Substernal Location | Central chest pain, classic ischemic pattern |
| 3 | Spread to Arm | Radiates to left arm, neck, jaw |
| 4 | Squeezing in Nature | Tight, heavy, or pressure-like pain |
| 5 | Short in Duration | <10 minutes, resolves with rest |
| 6 | Sublingual GTN Relief | Rapid response confirms ischemic origin |
Risk Factors for Stable Angina
- Age >50 years
- Hypertension
- Diabetes Mellitus
- Dyslipidemia
- Smoking
- Obesity
- Family history of CAD
- Sedentary lifestyle
- Stress and poor diet
Investigations for Suspected Stable Angina
1. ECG (at rest):
- May show normal results
- Can show old ischemic changes: ST depression, T-wave inversion
2. Stress Test:
- Treadmill test (TMT)
- Stress echocardiography
- Nuclear perfusion scanning
3. Echocardiogram:
- Assess LV function and wall motion
4. Coronary Angiography:
- Definitive for evaluating coronary artery stenosis
- Troponin: Normal in stable angina
- Lipid profile, HbA1c, renal function
Treatment of Stable Angina
1. Lifestyle Modification:
- Smoking cessation
- Regular exercise
- Weight reduction
- Heart-healthy diet (DASH/Mediterranean)
- Stress management
2. Pharmacological Therapy:
| Class | Drugs | Action |
|---|---|---|
| Nitrates | GTN, Isosorbide dinitrate | Vasodilation, ↓ preload, ↑ perfusion |
| Beta-blockers | Metoprolol, Atenolol | ↓ HR and myocardial oxygen demand |
| Calcium channel blockers | Amlodipine, Diltiazem | Coronary vasodilation |
| Antiplatelet agents | Aspirin, Clopidogrel | Prevent thrombosis |
| Statins | Atorvastatin, Rosuvastatin | Lower LDL, stabilize plaque |
| ACE Inhibitors | Ramipril, Lisinopril | Cardio-protective in diabetics and hypertensives |
3. Revascularization (for refractory symptoms):
- Percutaneous Coronary Intervention (PCI): Angioplasty + stenting
- Coronary Artery Bypass Grafting (CABG): For multi-vessel disease
Stable Angina vs. Unstable Angina
| Feature | Stable Angina | Unstable Angina |
|---|---|---|
| Trigger | Exertion or stress | Occurs at rest or minimal exertion |
| Duration | <10 min | >20 min |
| Response to GTN | Good | Partial or no relief |
| ECG | Often normal | ST depression or T-wave inversion |
| Troponin | Negative | Negative |
| Urgency | Outpatient management | Medical emergency |
Prognosis of Stable Angina
With proper medical management, lifestyle changes, and regular follow-up, stable angina has a good prognosis. However, lack of treatment may progress to unstable angina or myocardial infarction.
Red Flag Symptoms (Seek Emergency Care):
- Chest pain at rest
- Pain lasting >15 minutes
- New or worsening angina
- Syncope, palpitations, or breathlessness
Frequently Asked Questions (FAQs)
What is the “6S” mnemonic for stable angina?
The 6S mnemonic stands for: Sudden onset, Substernal, Spread to arm, Squeezing in nature, Short duration, and Sublingual GTN relief — capturing classic angina symptoms.
How do I know if my chest pain is angina?
If your chest pain starts with exertion, feels like pressure, radiates to the arm, and goes away with rest or nitrates — it’s likely angina. But always consult a doctor for ECG and evaluation.
Is stable angina reversible?
While the symptoms can be managed and the risk reduced, the underlying atherosclerosis is usually not reversible but can be slowed with lifestyle and medication.
Can women present differently?
Yes. Women may have more atypical symptoms such as fatigue, nausea, shortness of breath, or back pain instead of classic chest pain.
What is the first-line treatment for stable angina?
Lifestyle modification, nitrates for acute relief, beta-blockers for long-term symptom control, and aspirin/statins for cardiovascular protection.
Conclusion: Stability Begins with “6S”
Stable angina is a manageable yet serious cardiac condition that signals underlying coronary artery disease. Recognizing the “6S” — sudden onset, substernal location, spread to arm, squeezing quality, short duration, and sublingual relief — can lead to early diagnosis, better treatment, and improved outcomes.
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