What does coronary calcium score mean?

Dr. Jayanth H. K. MD.Department of Radiology

Augusta University.

How to calculate cardiovascular risk?

• Do you know your own CV risk? If you do not go to this site below to calculate.

• http://cvdrisk.nhlbi.nih.gov/• Framingham CV risk calculator uses age,

gender, total cholesterol, HDL cholesterol, smoking history, systolic BP and if on medications for hypertension.

What is the science behind coronary artery calcium (CAC)?

• CAC is pathognomonic for coronary artery atherosclerosis.

• Multiple studies have validated the risk of CV event increases linearly with high CAC scores.

• CAC scoring is the most powerful predictor of subclinical atherosclerosis and it is underused clinically.

Who should get coronary calcium score?

• Guidelines for coronary calcium scoring by 2010 ACCF task force.

• Intermediate cardiovascular risk and asymptomatic adults- Class IIA.

• Low to intermediate risk and asymptomatic adults-Class- IIB.

• Low risk and asymptomatic-class III.• Asymptomatic adults with diabetes, 40 years of

age and older- Class IIA.

History of looking for CAC.

• Chest radiographs• Fluoroscopy• Cardiac catheterization• EBCT• MDCT

Background

• MI as you all know is a silent killer.• 50% or more of these occur in individuals who

have no clue they are at risk of sudden cardiac event

• CAC score gives added benefit to traditional CV risk calculators

Procedure

• Noninvasive• Scan time 5-15 seconds• No contrast• Score is calculated on a workstation with

software

Coronary Calcium Score

• 0 none• 1-99 mild• 100-400 moderate• >400 severe• CAC score correlates linearly with risk of CV

events and obstructive CAD

http://www.mesa-nhlbi.org/calcium/input.aspx

• Input your age, select your gender and race/ethnicity, input (optionally) your observed calcium score and click “Calculate”

• This will convert the raw CAC score into a relative risk percentile

• No Indian race but chinese is there?

What does CAC score “0” mean?

• One may still have noncalcified atherosclerotic plaque

• Multiple studies have shown only a 0.11 % annual event rate and 1.1% 10 year risk in asymptomatic patients with 0 CAC scores.

Correlation with obstructive disease and symptomatic patients

• CAC presence indicates coronary atherosclerosis.

• Amount of CAC only weakly correlates with degree of luminal narrowing

• Likelihood of obstructive CAD certainly increases with increasing CAC scores

CAC score relative risks from MESA study

Hazard ratio

• 0 reference• 1-100 3.61• 101-300 7.73• >300 9.67• Similar prognostic value of CAC scoring has

been shown to be excellent in multiple large studies.

Advantages

• Easily to do and fairly highly reproducible• Identify at CV risk individuals earlier• If CAC present patient may be more compliant

with statins• Identify low risk patient who doesn’t need a

statin• Cost effective

Disadvantages

• Radiation• Cost• More testing

Radiation dose

• About 1mSv.• Background per year 3 mSv.• Mammogram 0.6 mSv.• CXR 0.04- 0.06 mSv.• Head CT 1-2 mSv.• Chest CT 5-7mSv.• Coronary catheterisation 3-5 mSv

Comparison to other biomarkers

• CAC scoring is superior to HS-CRP in predicting cardiac events

• CAC was more predictive of coronary disease than was carotid IMT

Conclusion

• CAC scoring is a well validated risk assessment tool that represents a major advance in screening for CAD

• The evidence is sound and physicians must be made aware on the ways to incorporate this screening tool into clinical practice

• More research is needed on CAC progression and regression using various treatments for CAD

Case 1

Impression•

1. There is calcified coronary plaque. Total calcium score = 235. Thehighest density of these calcifications are at the bifurcation of theleft main into LAD and circumflex coronary artery.

•2. Based on the MESA study, the calcium score is 67 percentile for ageand gender.

•3. The 5-year risk of cardiac events is estimated to be 78 % based onthis calcium score.

•4. Recommendations: Follow up with primary care provider. Primaryprevention for atherosclerotic cardiovascular disease as indicated byclinical measures.

• 5. Subsequent stress echocardiogram showed no functional stenosis.

• No data available to get repeat CAC scores after starting treatment

References

• 1. Detrano R, Guerci AD, Carr JJ et-al. Coronary calcium as a predictor of coronary events in four racial or ethnic groups. N. Engl. J. Med. 2008;358 (13): 1336-45.

• 2. http://cvdrisk.nhlbi.nih.gov/• 3. 2010 ACCF/AHA Guideline for Assessment

of Cardiovascular Risk in Asymptomatic Adults.

• 4. Agatston AS, Janowitz WR, Hildner FJ et-al. Quantification of coronary artery calcium using ultrafast computed tomography. J. Am. Coll. Cardiol. 1990;15 (4): 827-32.

• 5. Problem solving in Cardiovascular imaging by Suhny Abbara and Sanjeva P.Kalva.