Coronary Artery Disease and Angina

CAD & Angina Basics - Heart's Cry for Help

• Coronary Artery Disease (CAD): Atherosclerosis of epicardial coronary arteries leading to reduced myocardial perfusion.
• Angina Pectoris: Symptomatic, transient myocardial ischemia; typically chest discomfort/pressure due to O₂ supply < demand.
  • Supply ↓: Atherosclerosis (most common, >70% stenosis often symptomatic), coronary spasm, arteritis.
  • Demand ↑: Exercise, emotional stress, HTN, aortic stenosis.
• Pathophysiology: Endothelial dysfunction → lipid accumulation → atheromatous plaque formation → progressive luminal narrowing.
• Major Risk Factors:
  • Non-Modifiable: Age (Male >45y, Female >55y), Male sex, Family Hx (1st degree relative with premature CAD: M <55y, F <65y).
  • Modifiable: Smoking, Hypertension, Diabetes Mellitus, Dyslipidemia (↑LDL, ↓HDL, ↑Triglycerides), Obesity, Sedentary lifestyle. 📌 Mnemonic (Modifiable): "SHODDS" - Smoking, Hypertension, Obesity, Diabetes, Dyslipidemia, Sedentary.

⭐ Stable angina typically manifests when a coronary artery is narrowed by >70% of its luminal diameter (critical stenosis).

Angina Varieties - Chest Pain Flavors

• Stable Angina (Effort Angina)
  • Predictable, exertional pain; relieved by rest/NTG (<5 min).
  • Fixed coronary stenosis (>70%).
• Unstable Angina (UA)
  • New onset, crescendo, or rest angina (>20 min).
  • High-risk ACS; plaque rupture/thrombosis.
• Prinzmetal (Variant) Angina
  • Coronary artery spasm; often at rest, nocturnal.
  • Transient ST ↑ on ECG during pain.
  • Rx: CCBs, nitrates. ⚠️ Avoid non-selective β-blockers.
• Microvascular Angina (Syndrome X)
  • Angina with normal epicardial coronaries; microvascular dysfunction.
• Silent Ischemia
  • Asymptomatic ischemia; detected by ECG/stress test.
  • Common in diabetics, elderly.

  ⭐ Prinzmetal angina uniquely shows transient ST-segment elevation during chest pain episodes, unlike other anginas.

Diagnostic Toolkit - Peeking at Pipes

• Electrocardiogram (ECG):
  • Resting: ST↓, T-inversion, Q-waves (old MI). Often normal in stable angina (~50%).
  • Stress ECG (TMT): Provokes ischemia; monitors for ST changes.
• Cardiac Biomarkers (for ACS):
  • Troponin I/T: ↑ 3-6 hrs, peak 12-24 hrs. Highly sensitive/specific.
  • CK-MB: ↑ 4-6 hrs, normalizes 48-72 hrs (reinfarction).
• Non-Invasive Imaging:
  • Stress Echocardiography/MPI: Detect ischemia (wall motion/perfusion defects).
  • CCTA (Coronary CT Angiography): Anatomical assessment. High Negative Predictive Value.
• Invasive Coronary Angiography (CAG):
  • Gold standard. Defines anatomy, guides revascularization (PCI/CABG).
  • Fractional Flow Reserve (FFR) < 0.80 or iFR < 0.89 indicates significant stenosis.

⭐ CAG is indicated in patients with high pre-test probability, positive stress tests with high-risk features, or inconclusive non-invasive tests.

Treatment Strategies - Calming the Storm

Goals: Relieve angina, prevent MI & death.

• Medical Therapy (ABCDE Approach):
  • Antiplatelets: Aspirin (75-150mg), Clopidogrel. DAPT crucial post-PCI.
  • Beta-blockers: 1st line stable angina (e.g., Metoprolol).
  • Cholesterol-lowering (Statins): High-intensity (Atorvastatin 40-80mg). Target LDL < 55 mg/dL (very high risk).
  • Drugs for symptoms & Diet:
    • Nitrates (GTN SL 0.3-0.6mg PRN, ISMN/ISDN): Vasodilators (SE: headache, tolerance).
    • CCBs (Amlodipine; Verapamil/Diltiazem for rate control if β-blockers C/I).
    • Others: Ranolazine, Nicorandil, Ivabradine (for HR control if β-blockers not tolerated/sufficient).
  • ECE Inhibitors/ARBs: If HTN, DM, LV dysfunction, or post-MI.
• Revascularization:
  • PCI (stenting) or CABG for severe/refractory disease or high-risk anatomy.
• 📌 Acute Management (ACS): MONA-BASH (Morphine, $O_2$, Nitrates, Aspirin, β-blocker, ACEi, Statin, Heparin).

⭐ Beta-blockers are C/I in Prinzmetal angina (risk of unopposed α-spasm); CCBs/nitrates are mainstay.

High‑Yield Points - ⚡ Biggest Takeaways

• Stable angina: Exertional chest pain, relieved by rest/nitrates; ECG: ST depression.
• Prinzmetal angina: Coronary spasm, ST elevation at rest; Rx: CCBs, nitrates; β-blockers contraindicated.
• Unstable angina: Rest angina or crescendo pattern; high MI risk, urgent management.
• Atherosclerosis: Most common cause of CAD.
• Coronary angiography: Gold standard diagnosis for CAD.
• Acute angina: Sublingual nitroglycerin is key.
• CAD medical therapy: Aspirin, statins, β-blockers (avoid in Prinzmetal).