Stable Angina Pectoris

A clinical syndrome of predictable chest discomfort precipitated by exertion or emotional stress and relieved by rest or nitrates, caused by transient myocardial ischemia without myocardial necrosis.

Aetiology

Primary Cause

  • Coronary Artery Disease (CAD)
    • Stable atherosclerotic plaque
    • Typically ≥70% luminal narrowing

Contributing Factors (↑ Demand or ↓ Supply)

Increased Myocardial Oxygen Demand
  • Exercise
  • Tachycardia
  • Hypertension
  • Emotional stress
Decreased Oxygen Supply
  • Anemia
  • Hypoxemia
  • Coronary spasm (rare in stable angina)

Pathophysiology

Coronary Blood Flow Limitation
  • Fixed stenosis limits coronary flow reserve
  • At rest: adequate perfusion
  • During exertion: inadequate supply → ischemia
Ischemic Cascade
  1. ↓ Perfusion
  1. Metabolic changes (↓ ATP, ↑ lactate)
  1. Diastolic dysfunction
  1. Systolic dysfunction
  1. ECG changes
  1. Chest pain

Epidemiology

  • Very common manifestation of chronic coronary syndrome
  • Prevalence increases with:
    • Age (>40 years)
    • Male sex (earlier onset)
  • Major global contributor to cardiovascular morbidity

Risk Factors

Modifiable
  • Smoking
  • Diabetes mellitus
  • Hypertension
  • Dyslipidemia
  • Obesity
  • Sedentary lifestyle
Non-Modifiable
  • Age
  • Male sex
  • Family history
 

Clinical presentation

Classical Symptom Complex (Typical Angina)
Defined by 3 cardinal features:
  1. Retrosternal chest discomfort
  1. Provoked by exertion or emotional stress
  1. Relieved by rest or nitrates (within minutes)
      • If all 3 → Typical angina
      • 2/3 → Atypical angina
      • ≤1 → Non-anginal chest pain
Character of Chest Pain (Important for Differentials)
Quality
  • Pressure / heaviness / squeezing
  • “Tight band” or “weight on chest”
  • Not sharp or stabbing (suggests non-cardiac)
Location
  • Central (retrosternal)
  • Diffuse (patient uses whole hand, not a finger)
Radiation
  • Left arm (ulnar distribution)
  • Neck / jaw
  • Back / interscapular region
  • Occasionally right arm or epigastrium
Duration
  • Typically 2–10 minutes
  • Rarely >20 minutes
If prolonged → consider Acute Coronary Syndrome
Precipitating & Relieving Factors
Triggers (↑ Myocardial O₂ Demand)
  • Physical exertion (walking uphill, climbing stairs)
  • Emotional stress
  • Cold weather (vasoconstriction)
  • Heavy meals (postprandial angina)
  • Sexual activity
Relief
  • Rest (↓ demand)
  • Sublingual nitrates (within 1–5 min)
 
Associated Symptoms (Autonomic & Ischemic)
  • Dyspnea (common “anginal equivalent”)
  • Diaphoresis
  • Fatigue
  • Nausea
  • Palpitations
Anginal Equivalents (High-Yield)
Especially in:
  • Diabetes mellitus (autonomic neuropathy)
  • Elderly
  • Women
Presentation may include:
  • Dyspnea (most common)
  • Unexplained fatigue
  • Dizziness or syncope
Physical Examination Findings
Often normal between episodes
During an episode:
  • Tachycardia
  • Elevated BP
  • S4 gallop (↓ ventricular compliance)
  • Transient mitral regurgitation (papillary muscle ischemia)
Chronic findings:
  • Signs of Coronary Artery Disease
    • Xanthelasma
    • Peripheral vascular disease
    • Carotid bruits
Functional Classification (CCS Grading)
Class
Description
I
Angina only with strenuous exertion
II
Slight limitation (walking fast, uphill)
III
Marked limitation (walking short distances)
IV
Angina at rest

Investigations

Stable angina is a clinical diagnosis - tests done look for coronary disease as the cause
Resting ECG
Purpose
  • Baseline comparison
  • Detect prior ischemia/infarction
Important: A normal ECG does not exclude ischemia
 
Findings
  • Often normal
  • Possible:
    • ST depression
    • T-wave inversion
    • LV hypertrophy
Exercise Stress Testing (Core Diagnostic Tool)
Indication
  • Suspected stable angina with intermediate pre-test probability
Mechanism
  • Provokes ischemia → reveals ECG changes
Positive Test Criteria
  • Horizontal/downsloping ST depression ≥1 mm
notion image
Duke Treadmill Score (Prognostic)
Formula
notion image
  1. Exercise Time (minutes)
      • Measured during treadmill test (commonly Bruce protocol)
      • Reflects functional capacity
      • Longer duration → better prognosis
  1. ST-Segment Deviation (mm)
      • Maximum horizontal or downsloping ST depression/elevation
      • Marker of myocardial ischemia
      • Greater deviation → worse prognosis
  1. Angina Index
      2. Value
      Description
      0
      No angina during test
      1
      Non-limiting angina
      2
      Exercise-limiting angina
Risk Stratification
DTS Score
Risk Category
4-Year Mortality
Clinical Interpretation
≥ +5
Low risk
<1%
Excellent prognosis
−10 to +4
Intermediate risk
~1–3%
Needs further evaluation
≤ −11
High risk
>3–5%
Consider angiography
Coronary Anatomy Assessment
CT Coronary Angiography
  • Non-invasive
  • Good for low–intermediate risk patients
Invasive Coronary Angiography (Gold Standard)
  • Direct visualization of stenosis
  • Allows intervention (PCI)
Indications:
  • High-risk features
  • Positive stress test with significant ischemia
  • Refractory symptoms
Laboratory Investigations
Cardiac Biomarkers
  • Troponin: normal in stable angina
Elevated → think ACS
Risk Stratification Labs
  • Lipid profile
  • HbA1c / fasting glucose
  • Renal function

Management

Lifestyle interventions

  • Diet and exercise advice
  • Smoking cessation
  • ↓ alcohol intake
  • BMI of 25 or less

Anti-anginal Therapy (Symptom Control)

Nitrates
  • Short-acting (e.g, ISDN, GTN):
    • Acute relief (first-line for attacks)
    • Isosorbide dinitrate 5 mg every 5 minute, max 3x/day
  • Long-acting:
    • Prevention
Mechanism:
  • Venodilation → ↓ preload → ↓ myocardial O₂ demand
Beta-Blockers (First-Line Maintenance)
  • Examples: propanolol, metoprolol, atenolol
  • Mechanism:
    • ↓ Heart rate
    • ↓ Contractility
      → ↓ oxygen demand
Indications:
  • First-line unless contraindicated
Calcium Channel Blockers (CCB)
  • Types:
    • DHP: amlodipine (vasodilation)
    • Non-DHP: verapamil, diltiazem (↓ HR)
Use:
  • Alternative or add-on to beta-blockers

Disease Modifying Therapy

Antiplatelet Therapy
  • Aspirin (first-line)
  • Clopidogrel if aspirin intolerance
Lipid-Lowering Therapy
  • High-intensity statins
  • Target: aggressive LDL reduction
ACE Inhibitors / ARBs
  • Especially in:
    • Diabetes
    • Hypertension
    • LV dysfunction

Revascularization

Indications
  • Persistent symptoms despite optimal medical therapy
  • High-risk findings on stress testing
  • Significant coronary stenosis
Modalities
1. Percutaneous Coronary Intervention (PCI)
  • Balloon angioplasty + stent
2. Coronary Artery Bypass Grafting (CABG)
  • Preferred in:
    • Left main disease
    • Triple vessel disease
    • Diabetics (better outcomes)