Coronary Calcium Score: The Cheap Test That Predicts Your Heart Attack Risk
Coronary calcium scoring (CAC) is a low-radiation CT that measures calcified plaque in the heart arteries. It costs ₹3,000-6,000, takes 5 minutes, and gives a single number that predicts heart attack risk better than any other simple test. It is under-ordered in India because it's not part of routine health packages, but for anyone with cardiovascular risk factors it is worth asking about.
What the score means
- Score: 0 · Interpretation: No calcified plaque · Approximate 10-year event risk: < 1% (very low)
- Score: 1-99 · Interpretation: Mild plaque · Approximate 10-year event risk: 1-3%
- Score: 100-299 · Interpretation: Moderate plaque · Approximate 10-year event risk: 3-10%
- Score: 300-999 · Interpretation: Significant plaque · Approximate 10-year event risk: 10-20%
- Score: > 1000 · Interpretation: Extensive plaque · Approximate 10-year event risk: > 20%
Why the score is useful
Traditional risk calculators (Framingham, ASCVD) use age, sex, BP, cholesterol, smoking, diabetes to estimate risk. They work at the population level but are imprecise for individuals. Calcium scoring measures actual disease in your actual arteries. It reclassifies risk up or down for many people, particularly in the 'intermediate risk' band where treatment decisions are hardest.
Who benefits most from having one
- Age 40-70 with cardiovascular risk factors (family history, borderline lipids, hypertension) making statin decision unclear.
- Family history of premature heart disease.
- Diabetes without other symptoms.
- South Asian ancestry with any risk factors (elevated baseline risk).
- Anyone about to start or refuse a statin based on borderline risk numbers.
Who does NOT need one
- Under 40 without strong family history — calcium hasn't had time to accumulate.
- Known coronary artery disease — the answer is already yes.
- Very low overall risk with no risk factors.
- Very high risk with clear indication for aggressive treatment — the test wouldn't change the plan.
What a score of zero means
A score of zero is genuinely reassuring — 10-year event risk is under 1%. Many cardiologists defer statin therapy in patients with score zero even if traditional calculators suggested it. A score of zero does not mean 'no plaque forever' — it means no calcified plaque now. Soft (non-calcified) plaque exists that this test misses, but the correlation with events is still strong.
What a high score means
A score above 100 identifies someone whose arteries are diseased, regardless of how they feel or how their traditional risk factors look. The response is typically: statin therapy (often more aggressive), BP tighter control, aspirin discussion, and closer follow-up. It does NOT automatically mean they need angiography — high calcium can coexist with normal blood flow. Symptoms plus a high score is a different picture from a high score alone.
The radiation reality
A calcium score CT uses about 1 mSv of radiation — roughly equivalent to a mammogram, or 3-4 months of natural background exposure. This is much less than a full contrast CT (10-20 mSv). For a person over 45 with risk factors, the diagnostic value is worth the small dose.
Once you have a score, keep the report in your record permanently. It doesn't need repeating for 5-10 years typically — calcification is slow to progress. A single well-timed calcium score in your 50s often shapes the next 20 years of cardiovascular management.
References
Free for 90 days, no card needed. After that, keeping the record costs ₹349 for the year.
General information, not medical advice. Always talk to a qualified doctor about your own care. Where this and your doctor disagree, your doctor is right.