## Investigation of Choice for Subclinical Atherosclerosis Detection **Key Point:** Coronary artery calcium (CAC) scoring by non-contrast CT is the gold standard for detecting and quantifying subclinical coronary atherosclerosis in asymptomatic individuals with intermediate cardiovascular risk. ### Why CAC Scoring? **High-Yield:** CAC score independently predicts future coronary events and is superior to traditional risk factors alone in risk stratification. It has: - High sensitivity and specificity for coronary atherosclerosis - Prognostic value: CAC = 0 indicates very low 10-year risk; CAC >400 indicates high risk - No radiation burden comparable to invasive angiography - Guides intensity of statin therapy and aspirin use ### Comparison of Investigations | Investigation | Purpose | Utility in Asymptomatic Patient | Limitation | |---|---|---|---| | **CAC scoring** | Detects coronary calcification | Identifies subclinical CAD; guides therapy intensity | Radiation exposure (low dose) | | **Exercise stress test** | Assesses inducible ischemia | Low sensitivity in asymptomatic; requires symptoms for interpretation | Requires exertional capacity; poor specificity | | **Echocardiography** | Assesses LV function, structure | Detects LV hypertrophy; not for CAD detection | Operator-dependent; no direct CAD assessment | | **Carotid IMT** | Measures arterial wall thickness | Marker of atherosclerotic burden | Surrogate marker; less predictive than CAC in coronary disease | **Clinical Pearl:** In Indian populations with high prevalence of metabolic syndrome and premature CAD, CAC scoring helps identify patients who would benefit from aggressive lipid-lowering and blood pressure control before symptomatic disease develops. **Tip:** Remember the CAC score categories: - 0 = very low risk - 1–99 = low risk - 100–399 = intermediate risk - ≥400 = high risk [cite:Park 26e Ch 10] 
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