Stable coronary artery disease

Pathophysiology - The Arterial Squeeze

• Demand-Supply Mismatch: Myocardial oxygen demand exceeds supply from stenosed coronary arteries, triggered by exertion or stress.
• Atherosclerotic plaque creates a fixed obstruction, preventing vessel dilation in response to ↑ demand.

⭐ Critical Stenosis: Significant ischemia and symptoms typically occur when the coronary artery lumen is narrowed by >70%. This is a key threshold for intervention.

Clinical Presentation & Diagnosis - Chest Pains & Clues

• Typical Angina (Classic Presentation): Meets all 3 criteria:
  • Substernal chest pressure, squeezing, or heaviness.
  • Provoked by physical exertion or emotional stress.
  • Relieved within 5-10 min by rest or nitroglycerin.
• Atypical Angina: Meets only 2 of the 3 criteria.
• Anginal Equivalents: Dyspnea on exertion, fatigue, nausea, diaphoresis. Common in women, diabetics, and the elderly.

⭐ Levine's Sign: Patient clenches a fist over their sternum to describe the pain-a classic, though not specific, indicator of ischemic chest pain.

Risk Stratification - Gauging the Danger

• Goal: Identify high-risk patients who benefit from revascularization over optimal medical therapy (OMT) alone.
• Primary Tool: Stress testing (exercise ECG, echo, or nuclear).
• High-Risk Markers:
  • Large ischemic defect (>10% myocardium).
  • Hypotension or significant ST depression at low workload.
  • ↓ LVEF with exercise.

⭐ High-risk angiographic findings mandating revascularization include >50% left main stenosis, three-vessel disease (especially with LVEF <50%), or two-vessel disease involving the proximal LAD.

• Decision Pathway:

Medical Management - The Pill Arsenal

• Antiplatelet: Aspirin 81 mg daily. Clopidogrel if aspirin-allergic.
• Beta-blockers: First-line for angina relief (e.g., Metoprolol).
• Cholesterol: High-intensity statin (Atorvastatin 40-80 mg).
• Diet/Diabetes & Exercise/Education.

⭐ Ranolazine is a key second-line agent that reduces angina frequency without affecting heart rate or blood pressure, making it ideal for patients with bradycardia or hypotension on other meds.

Revascularization - Plumbing the Pipes

Goal is symptom control; survival benefit only in high-risk subsets (e.g., left main disease).

• PCI (Percutaneous Coronary Intervention): Best for 1 or 2-vessel disease, non-complex lesions.
• CABG (Coronary Artery Bypass Grafting): Superior for left main, ≥3-vessel disease, or 2-vessel disease in diabetics.

⭐ The COURAGE trial showed that for stable angina, PCI did not reduce death or MI compared to optimal medical therapy, but did lead to greater symptom relief.

• Stable angina is exertional chest pain, relieved by rest or nitroglycerin.
• Pathophysiology involves fixed atherosclerotic plaques causing >70% coronary stenosis.
• Stress testing is the primary non-invasive diagnostic tool; ECG may show ST depression.
• Coronary angiography is the definitive gold standard diagnostic test.
• First-line medical therapy includes aspirin, beta-blockers, and high-intensity statins.
• Sublingual nitroglycerin is used for acute symptom relief.
• Aggressive risk factor modification is critical to slow disease progression.