Understanding Arterial Blockage: Causes, Risks & Severity
Atherosclerosis is the progressive buildup of plaque (lipids, cholesterol, calcium, inflammatory cells, fibrous tissue) in arterial intima, leading to luminal narrowing.
Coronary Artery Disease (CAD) Severity Grading
| Stenosis | Classification | Clinical Significance |
|---|
| <50% | Non-obstructive | May still cause events (plaque rupture); risk factor modification essential. |
| 50-69% | Moderate | Ischemia possible with stress; consider functional testing (stress test, FFR). |
| 70-90% | Severe | Likely flow-limiting; symptoms (angina) common; revascularization often beneficial. |
| >90% / Occlusion | Critical / Total | Rest pain, infarction risk; collateral-dependent; CTO PCI or CABG. |
Risk Factors (Modifiable & Non-Modifiable)
- Non-modifiable: Age, male sex, family history, genetics (9p21, PCSK9).
- Modifiable: Hypertension, dyslipidemia (↑LDL, ↓HDL), diabetes, smoking, obesity, sedentary, diet, psychosocial stress.
- Emerging: Lp(a), hs-CRP, coronary calcium score (CAC).
Pathophysiology of Events
Most MIs arise from plaque rupture/erosion at non-severe stenoses (<50-70%) → thrombus → occlusion. Hence, "vulnerable plaque" (large lipid core, thin fibrous cap, inflammation) matters more than degree of narrowing alone.
Diagnostic Evaluation
- Non-invasive: CAC scoring, CT angiography, stress testing (exercise, pharmacologic + imaging).
- Invasive: Coronary angiography (gold standard), FFR/iFR (physiologic significance).
Treatment
- Lifestyle: Mediterranean diet, exercise, smoking cessation, weight management.
- Medical: High-intensity statin, antiplatelet (aspirin), BP control, diabetes management (SGLT2i, GLP-1 RA), PCSK9 inhibitors if needed.
- Revascularization: PCI (stent) or CABG for symptom relief (angina) or prognosis (left main, multivessel, diabetes, reduced EF).
Key Message
Even mild atherosclerosis increases risk. Aggressive risk factor modification is the cornerstone; revascularization targets flow-limiting lesions or high-risk anatomy.
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