Coronary Artery Calcium Score
Understand Coronary Artery Calcium Score in Heart Cardiac CT imaging, what it means, and next steps.
30-Second Overview
High-attenuation plaques (>130 HU) in coronary artery distribution; Agatston score calculated: 0 (none), 1-10 (minimal), 11-100 (mild), 101-400 (moderate), >400 (severe)
CAC score is the single best predictor of coronary events. Score >100 indicates 10-year cardiac event risk ~7-10%. Zero score confers very low risk (NPV 95-99%)
benignRate
followUp
Imaging Appearance
Cardiac CT FindingHigh-attenuation plaques (>130 HU) in coronary artery distribution; Agatston score calculated: 0 (none), 1-10 (minimal), 11-100 (mild), 101-400 (moderate), >400 (severe)
Clinical Significance
CAC score is the single best predictor of coronary events. Score >100 indicates 10-year cardiac event risk ~7-10%. Zero score confers very low risk (NPV 95-99%)
Understanding Coronary Artery Calcium Score
Coronary artery calcium (CAC) scoring is a non-invasive CT scan that measures the amount of calcified plaque in your coronary arteries. The calcium score helps predict your risk of heart attack and guides decisions about preventive therapy.
Agatston score quantifies coronary calcium: 0 (none), 1-10 (minimal), 11-100 (mild), 101-400 (moderate), ＞400 (severe)
Here's how accurate CAC scoring is for predicting cardiac risk:
Zero score = very low risk; ＞400 = high risk
Correctly rules out healthy patients
Annual new cases
Think of coronary calcium like rust in a pipe—calcified plaque is a sign of long-standing atherosclerosis. The more calcium present, the more plaque burden in your arteries, and the higher your risk of heart attack.
What Is Coronary Artery Calcium?
Coronary artery calcium is a marker of atherosclerotic plaque buildup. Calcium develops in plaques as they age and stabilize. While calcified plaque itself may not be the most dangerous type, it serves as a useful marker of overall plaque burden.
Understanding the Agatston Score:
| Score Category | Agatston Score | Plaque Burden | 10-Year Risk Category | |----------------|----------------|---------------|----------------------| | Zero | 0 | No calcified plaque detected | Very low risk | | Minimal | 1-10 | Small amount of calcium | Low risk | | Mild | 11-100 | Mild plaque burden | Moderate risk | | Moderate | 101-400 | Moderate plaque burden | Moderate to high risk | | Severe | ＞400 | Extensive plaque burden | High risk |
Why CAC scoring is valuable:
- Non-invasive and quick (5-10 minute scan)
- No IV contrast needed
- Low radiation dose (~1 mSv)
- Excellent risk stratification tool
- Helps guide statin and aspirin decisions
- Motivates lifestyle changes
How CAC Scoring Is Performed
A coronary calcium score is obtained using a specialized cardiac CT scan with ECG gating to minimize motion artifact from the beating heart.
What Zero Calcium Score Looks Like
No high-attenuation lesions (＞130 HU) visualized along the course of coronary arteries. LAD, LCX, and RCA are followed throughout their course. No calcifications detected. Agatston score = 0. This indicates very low risk of cardiac events.
What Elevated Calcium Score Looks Like
Bright white (high attenuation) foci along coronary artery courses representing calcified plaque. Scored by area and density. Distribution: LAD most commonly affected. Agatston score calculated based on number, size, and density of lesions. Higher scores indicate more extensive atherosclerosis.
Key Findings Pattern
When interpreting CAC scoring, radiologists assess:
Key Imaging Findings
Agatston score
Quantitative score based on lesion area and density threshold (＞130 HU)
Number of calcified lesions
Count of distinct calcified plaques in coronary arteries
Distribution pattern
Which vessels are affected: LAD, LCX, RCA, or branches
Percentile ranking
Comparison to age, sex, and ethnicity-matched population
Non-calcified plaque
Soft plaque not detected on calcium scoring (requires CTA with contrast)
Extra-coronary findings
Incidental findings in chest (lung nodules, aortic aneurysm, etc.)
When Your Doctor Orders This Test
Here's a typical scenario where CAC scoring is ordered:
Clinical Scenario
Common indications for CAC scoring:
- Intermediate risk patients for risk reclassification
- Asymptomatic adults 40-75 years with family history of premature CAD
- Decision-making about statin therapy (borderline risk)
- Patients reluctant to start statins (visual evidence can motivate)
- Assessment before beginning intensive exercise programs
Who should NOT have CAC scoring:
- Patients with known coronary artery disease (already indicated for treatment)
- Low-risk patients (unlikely to change management)
- High-risk patients (already indicated for aggressive therapy)
- Pregnant women
- Patients with atrial fibrillation (irregular rhythm limits scan quality)
Differential Diagnosis
Several conditions can produce findings on calcium scoring:
What Else Could It Be?
High-attenuation lesions (＞130 HU) along coronary artery distribution. Scored using Agatston method. Indicates atherosclerosis. Management: statin, aspirin, lifestyle modification based on score and clinical risk.
Soft plaque does not meet density threshold for detection. CAC score may be zero despite significant plaque burden, especially in younger patients. Consider coronary CTA if clinical suspicion high.
Very high density, typically cylindrical shape. History of prior PCI. Not scored as part of Agatston score but noted. Indicates known CAD already under treatment.
Calcification in mitral valve annulus, not coronary artery. Distinct location at base of heart. Associated with aging, kidney disease, hypertension. Not scored in CAC but reported.
Calcification in pericardium, not coronary arteries. May indicate prior pericarditis. Not included in Agatston score. Reported separately if present.
How Accurate Is CAC Scoring?
CAC scoring is a well-validated tool for cardiovascular risk assessment:
A zero calcium score indicates very low risk of cardiac events in the next 2-5 years. This high NPV makes CAC scoring an excellent rule-out test, allowing patients to avoid unnecessary medications if they have no calcified plaque.
Patients with Agatston score ＞400 have significantly elevated cardiovascular risk, comparable to patients with known CAD. This finding warrants aggressive preventive therapy including statin, aspirin, and lifestyle modification.
CAC scoring is particularly useful for patients at intermediate risk where treatment decisions are uncertain. Half of these patients are reclassified into lower or higher risk categories, guiding appropriate therapy.
What Happens Next?
Management depends on CAC score and overall cardiovascular risk:
What Happens Next?
Score interpretation and risk discussion
Zero score: low short-term risk, discuss preventive strategies. Mild score (1-100): consider statin based on risk factors. Moderate score (101-400): statin usually indicated. Severe score (＞400): statin + aspirin, consider cardiac evaluation.
Lifestyle modification (all patients)
Heart-healthy diet (Mediterranean pattern). Regular aerobic exercise (150 min/week). Weight management. Smoking cessation if applicable. Stress reduction. Sleep hygiene. These changes benefit all patients regardless of score.
Statin therapy decision
CAC=0 in low-risk: statin may be deferred. CAC 1-100: statin based on risk factors and preferences. CAC 101-400: statin typically recommended. CAC ＞400: high-intensity statin indicated. Score helps visualize risk and motivate adherence.
Aspirin consideration
Low scores: aspirin generally not indicated. Moderate scores: aspirin may be considered. High scores (＞400): low-dose aspirin often recommended unless contraindicated. Shared decision-making regarding bleeding risk.
Follow-up and surveillance
CAC=0: no repeat scanning needed for 5+ years. Low scores: repeat at 3-5 year intervals if clinical uncertainty. Moderate/high scores: focus on risk factor control rather than repeat scoring. Control cholesterol, blood pressure, diabetes.
What Your Score Means
- 0: No calcified plaque detected. Very low cardiac risk. Focus on maintaining healthy habits.
- 1-10: Minimal calcium. Low risk. Continue healthy lifestyle; discuss statin based on other risk factors.
- 11-100: Mild calcium. Moderate risk. Statin therapy often recommended; lifestyle modification essential.
- 101-400: Moderate calcium. Increased risk. Statin therapy indicated; consider aspirin; aggressive risk factor control.
- ＞400: Severe calcium. High risk. High-intensity statin, aspirin, cardiac consultation; treat as if you have known CAD.
Frequently Asked Questions
Does a zero score mean my heart is healthy?
A zero calcium score means no calcified plaque was detected, which indicates very low risk of heart attack in the next 2-5 years. However, it doesn't guarantee perfect heart health. You can still have non-calcified plaque (especially if young) or other cardiac conditions. Continue healthy habits and see your doctor regularly.
Do I need to be on a statin if my calcium score is high?
If your calcium score is elevated (＞100, and especially ＞400), statin therapy is typically recommended regardless of your cholesterol levels. Statins stabilize plaque and reduce cardiac events. The decision should be made with your doctor considering your overall risk, age, and preferences.
How often should I repeat calcium scoring?
Repeat scoring is not routinely recommended. If your initial score is zero, repeat at 5+ year intervals if clinical uncertainty remains. If you have an elevated score, the focus should be on risk factor control and preventive therapy rather than repeat scanning. The score primarily guides initial treatment decisions.
Can I lower my calcium score?
Once calcium deposits form, they don't disappear with treatment. However, statins and lifestyle changes can prevent progression and stabilize soft plaque before it calcifies. The goal is not to reduce the score but to prevent new calcium from forming and reduce overall cardiovascular risk.
Should I be worried about radiation exposure?
The radiation dose from CAC scoring is very low (~1 mSv), similar to a mammogram and far less than a diagnostic coronary CTA (~3-5 mSv). This small risk is generally outweighed by the benefit of accurate cardiovascular risk assessment, especially when the results will guide preventive therapy decisions.
References
Medical References
This content is referenced from authoritative medical organizations:
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Medical Disclaimer: This information is for educational purposes. Cardiovascular risk assessment requires guidance by a healthcare provider. Always seek medical care for cardiac symptoms.
Correlate with Lab Results
When Coronary Artery Calcium Score appears on imaging, doctors often check these lab tests:
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