Coronary artery calcium scoring
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Fahad AlKhalfan, M.D.,Tarek Nafee, M.D. [2]
Overview
The presence of coronary artery calcification indicates underlying CHD.[1] The coronary artery calcium (CAC) scan is a non-contrast CT scan used to visualize the extent of calcification in the coronary vessels.[2] While there is a strong correlation between CAC burden and coronary plaque area, CAC scans do not identify noncalcified plaques that are capable of erosion or rupture and therefore may not be a good predictor of luminal obstruction. [1]
The role of CAC in patients with low or intermediate risk of developing a CHD event is uncertain. However, it is not indicated for patients at high risk of CHD as aggressive preventative measures would have already been initiated.
Coronary Artery Calcium Scoring Systems
Agatston Method
 |
- The Agatston score is a scoring system that uses images obtained from a non-contrast CT.
- It is determined by the number of calcific lesions, the area of each lesion and the peak HU of each lesion detected. The score for every calcific lesion is based on its density score and area (mm2).[3]
- The density score is determined by the peak HU and is as follows:
- 1 = 130 - 199 HU
- 2 = 200 - 299 HU
- 3 = 300 - 399 HU
- 4 = >399 HU
- If a lesion had a peak HU of 250 and an area of 4 mm2, it would receive a score of 8.
- The CAC is the sum of the scores assigned to each calcific lesion.
- The degree of calcification has also been shown to vary depending on certain demographic factors including age, gender and ethnicity.
- Taking this into consideration, the CAC score using the Agatston method can either be presented as an absolute value or as a percentile after adjusting for these three factors.[4] Percentiles can be obtained from the Multi-Ethnic Study of Atherosclerosis (MESA) website.
The CAC can be stratified as the following:[4][5]
| Coronary Artery Calcium Score | CAC Score Percentile
(after adjustment) |
Calcification Grade | Interpretation |
|---|---|---|---|
| 0 | 0 | None | Very low risk of future CHD event |
| 1-10 | ≤75 | Minimum | Low risk of future CHD event, low probability of MI |
| 11-100 | Mild | ||
| 101-400 | 76-90 | Moderate | Increased risk of future CHD event |
| >400 | >90 | Severe | Increased probability of MI |
Calcium Volume Score
- The calcium volume score is calculated by multiply the number of voxels with calcification by the volume of each voxel. This would include all voxels with a HU score of greater than 130.[4]
Relative Calcium Mass Score
- The relative calcium mass score is calculated by multiplying the mean attenuation of the calcified plaque by the plaque volume in each image. [4]
Role of CAC score in Clinical Practice
- The presence of CAC indicates underlying CHD.
- While there is a strong correlation between CAC burden and coronary plaque area, CAC scans do not identify noncalcified plaques that are capable of erosion or rupture. Therefore, CAC is not a good predictor of luminal obstruction.[1]
- CAC scores have been shown to improve upon the current Framingham Risk Score, providing a significant increase in the accuracy of risk stratification.[4][1] However, there is no prospective data that indicates that CAC screening results in a reduction of coronary events.[1]
- CAC has also been demonstrated to be an independent predictor of major cardiovascular events.[4]
CAC Scores in Asymptomatic Patients
- Various studies have shown that asymptomatic patients with a CAC score of zero have a low risk of CHD event in the long term.[4]
- The use of the CAC score is not indicated in asymptomatic high risk patients as aggressive preventive measures would have already been initiated.[4]
- Guidelines regarding the use of CAC in low and intermediate risk individuals have not been consistent.
- In 2010, the American College of Cardiology stated that the use of CAC is appropriate in asymptomatic, low risk individuals with a family history of CHD and in individuals with an intermediate risk of CHD (10%-20% 10 year risk of CHD).[6] However, this has changed in the 2013 guidelines.
- The latest recommendation by the ACC is that CAC can be used to guide risk based decision making if after quantitative risk assessment, a risk based decision is uncertain.[7]
- Due to concerns related to cumulative radiation exposure, routine serial CAC scans are not currently recommended.[1]
CAC Scores in Symptomatic Patients
- The use of the CAC score alone is limited in symptomatic patients.
- The pretest probability of a CHD event should always be considered when interpreting a CAC score.[4]
- The ACCF/AHA Expert Consensus suggests that the CAC score can be used to help rule out obstructive coronary disease in low risk patients presenting with atypical chest pain.[8]
- The National Institute for Health and Care Excellence (NICE) recommends that a CAC score can be used in patients with chest pain and a 10% to 29% estimated likelihood of CAD (based on the modified Diamond and Forrester Criteria).[9] If the CAC is:
- 0: Consider other causes of chest pain
- 1-400: Offer CT coronary angiography
- >400: Offer invasive coronary angiography.
Latest Guidelines
| Guideline | Recommendation | Class | Level of Evidence |
|---|---|---|---|
| 2013 ACC/AHA Guideline on the Assessment of Cardiovascular Risk [7] | If after quantitative risk assessment, a risk-based decision is uncertain, one or more of the following tools may be used to aid in decision making: family history, hs-CRP, CAC score or ABI. | IIb | B |
| 2016 European Guidelines on Cardiovascular Disease Prevention In Clinical Practice [10] | CAC may be considered as a risk factor in CV risk assessment in patients with a calculated SCORE risk between 5% to 10%. | IIb | B |
| Guideline | Recommendation | ||
| ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR
2010 Appropriate Use Criteria for Cardiac Computed Tomography [11] |
CAC would be appropriate in patients with a 10-20% 10-year risk of CHD. | Appropriate | |
| CAC would be appropriate in low risk patients (<10% 10-year risk of CHD) with a family history of premature CHD. | Appropriate | ||
| The usefulness of CAC is uncertain in patients with peripheral arterial disease or other coronary risk equivalents, or have a 10-year CHD risk greater than 20%, or who are 40 or older with diabetes. | Uncertain | ||
| CAC would be inappropriate in low risk patients (<10% 10-year risk of CHD). | Inappropriate | ||
| National Institute for Health and Care Excellence (NICE) Guidance.
Chest Pain of Recent Onset: Assessment and Diagnosis of Recent Onset Chest Pain or Discomfort of Suspected Cardiac Origin. (2010)[9] |
The CAC score can be used in patients with chest pain and a 10% to 29% estimated likelihood of CAD. | ||
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Shah NR, Coulter SA (2012). "An evidence-based guide for coronary calcium scoring in asymptomatic patients without coronary heart disease". Tex Heart Inst J. 39 (2): 240–2. PMC 3384065. PMID 22740742.
- ↑ Hecht HS (2015). "Coronary artery calcium scanning: past, present, and future". JACC Cardiovasc Imaging. 8 (5): 579–96. doi:10.1016/j.jcmg.2015.02.006. PMID 25937196.
- ↑ Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Viamonte M, Detrano R (1990). "Quantification of coronary artery calcium using ultrafast computed tomography". J Am Coll Cardiol. 15 (4): 827–32. PMID 2407762.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Neves PO, Andrade J, Monção H (2017). "Coronary artery calcium score: current status". Radiol Bras. 50 (3): 182–189. doi:10.1590/0100-3984.2015.0235. PMC 5487233. PMID 28670030.
- ↑ van der Bijl N, Joemai RM, Geleijns J, Bax JJ, Schuijf JD, de Roos A; et al. (2010). "Assessment of Agatston coronary artery calcium score using contrast-enhanced CT coronary angiography". AJR Am J Roentgenol. 195 (6): 1299–305. doi:10.2214/AJR.09.3734. PMID 21098187.
- ↑ Greenland P, Alpert JS, Beller GA, Benjamin EJ, Budoff MJ, Fayad ZA; et al. (2010). "2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines". J Am Coll Cardiol. 56 (25): e50–103. doi:10.1016/j.jacc.2010.09.001. PMID 21144964.
- ↑ 7.0 7.1 Goff DC, Lloyd-Jones DM, Bennett G, Coady S, D'Agostino RB, Gibbons R; et al. (2014). "2013 ACC/AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines". Circulation. 129 (25 Suppl 2): S49–73. doi:10.1161/01.cir.0000437741.48606.98. PMID 24222018.
- ↑ Greenland P, Bonow RO, Brundage BH, Budoff MJ, Eisenberg MJ, Grundy SM; et al. (2007). "ACCF/AHA 2007 clinical expert consensus document on coronary artery calcium scoring by computed tomography in global cardiovascular risk assessment and in evaluation of patients with chest pain: a report of the American College of Cardiology Foundation Clinical Expert Consensus Task Force (ACCF/AHA Writing Committee to Update the 2000 Expert Consensus Document on Electron Beam Computed Tomography) developed in collaboration with the Society of Atherosclerosis Imaging and Prevention and the Society of Cardiovascular Computed Tomography". J Am Coll Cardiol. 49 (3): 378–402. doi:10.1016/j.jacc.2006.10.001. PMID 17239724.
- ↑ 9.0 9.1 Skinner JS, Smeeth L, Kendall JM, Adams PC, Timmis A, Chest Pain Guideline Development Group (2010). "NICE guidance. Chest pain of recent onset: assessment and diagnosis of recent onset chest pain or discomfort of suspected cardiac origin". Heart. 96 (12): 974–8. doi:10.1136/hrt.2009.190066. PMID 20538674.
- ↑ Piepoli MF, Hoes AW, Agewall S, Albus C, Brotons C, Catapano AL; et al. (2016). "2016 European Guidelines on cardiovascular disease prevention in clinical practice: The Sixth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of 10 societies and by invited experts)Developed with the special contribution of the European Association for Cardiovascular Prevention & Rehabilitation (EACPR)". Eur Heart J. 37 (29): 2315–81. doi:10.1093/eurheartj/ehw106. PMC 4986030. PMID 27222591.
- ↑ Taylor AJ, Cerqueira M, Hodgson JM, Mark D, Min J, O'Gara P; et al. (2010). "ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomography. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance". J Cardiovasc Comput Tomogr. 4 (6): 407.e1–33. doi:10.1016/j.jcct.2010.11.001. PMID 21232696.