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CAC Score (Coronary Calcium) Longevity-Medicine Target Ranges

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At a glance

  • CAC 0 / unfavorable modeled aspirin balance [1]
  • CAC 100 or higher / favorable modeled aspirin balance [1]
  • Aspirin estimates / 5-year number needed to treat 2,036 and 808 at CAC 0; 173 and 92 at CAC 100 or higher [1]
  • Number needed to harm / 442 for a major bleed in the same model [1]
  • Adding CAC to risk factors / net reclassification improvement 0.25 [2]
  • Rapid progression / among people who already had CAC, 300 or more Agatston units a year carried HR 6.3 for hard CHD [3]

What a CAC Score Measures

A CAC score is measured by computed tomography and reported in Agatston units [2][3]. Zero means no coronary calcium was detected.

Where the MESA Data Separate: Zero and 100

A modeling study followed 4,229 MESA participants free of diabetes and not taking aspirin at baseline for a median of 7.6 years, then applied an 18% relative reduction in coronary heart disease events to the observed event rates [1]. The estimated 5-year numbers needed to treat with aspirin were:

  • CAC 0, 10-year Framingham risk below 10%: 2,036 [1]
  • CAC 0, risk 10% or higher: 808 [1]
  • CAC 100 or higher, risk below 10%: 173 [1]
  • CAC 100 or higher, risk 10% or higher: 92 [1]

Against an estimated 5-year number needed to harm of 442 for a major bleed, CAC 0 had an unfavorable balance and CAC 100 or higher a favorable one in both risk strata [1]. These are modeled estimates, not a randomized trial that assigned aspirin by CAC score, and sex-specific and age-stratified analyses gave similar results [1].

Does Adding CAC Improve Risk Prediction?

MESA measured CAC in 6,814 participants without known cardiovascular disease, recruited between July 2000 and September 2002. The primary analysis excluded participants with diabetes and included a final cohort of 5,878. Over a median 5.8 years there were 209 coronary heart disease events, 122 of them myocardial infarction, CHD death or resuscitated cardiac arrest [2]. Adding CAC to standard risk factors improved classification, with a net reclassification improvement of 0.25 (95% CI 0.16 to 0.34, P<0.001) [2].

Does Progression Add Information?

In 6,778 MESA participants aged 45 to 84, 5,682 had a second scan about 2.5 years after the first, with median follow-up of 7.6 years and 206 hard CHD events. The average annual change in CAC was 24.9 Agatston units [3]. Among participants who already had detectable calcium at baseline, an increase of 300 or more Agatston units per year was associated with an adjusted hazard ratio of 3.8 (95% CI 1.5 to 9.6) for total CHD and 6.3 (1.9 to 21.5) for hard CHD compared with no progression [3].

Frequently asked questions

Is there a longevity-medicine CAC target range?
The MESA data do not define one. The MESA aspirin model compared CAC 0 with CAC 100 or higher [1].
What does a CAC score of zero mean in this data?
Zero means no coronary calcium was detected, and in the MESA aspirin model it was the value with an unfavorable estimated balance: a 5-year number needed to treat of 2,036 at Framingham risk below 10% and 808 at 10% or higher, against a number needed to harm of 442 [1].
What does a CAC score of 100 or higher mean?
In the same model, CAC 100 or higher had a favorable estimated aspirin benefit-to-bleeding balance, with a 5-year number needed to treat of 173 at Framingham risk below 10% and 92 at 10% or higher [1].
How fast should a CAC score rise?
The progression data report risk by size of change, not an acceptable cut-off. The average annual rise in MESA was 24.9 Agatston units, and among people who already had calcium at baseline, 300 units or more per year carried a hazard ratio of 6.3 for hard CHD compared with no progression [3].
Does adding CAC to standard risk factors improve prediction?
Yes, in MESA it improved risk classification, with a net reclassification improvement of 0.25 (95% CI 0.16 to 0.34, P<0.001) [2].

References

  1. Miedema MD, Duprez DA, Misialek JR, Blaha MJ, Nasir K, Silverman MG, et al. Use of coronary artery calcium testing to guide aspirin utilization for primary prevention: estimates from the multi-ethnic study of atherosclerosis. Circ Cardiovasc Qual Outcomes. 2014;7(3):453-60. Use of coronary artery calcium testing to guide aspirin utilization for primary prevention: estimates from the multi-ethnic study of atherosclerosis
  2. Polonsky TS, McClelland RL, Jorgensen NW, Bild DE, Burke GL, Guerci AD, et al. Coronary artery calcium score and risk classification for coronary heart disease prediction. JAMA. 2010;303(16):1610-6. Coronary artery calcium score and risk classification for coronary heart disease prediction
  3. Budoff MJ, Young R, Lopez VA, Kronmal RA, Nasir K, Blumenthal RS, et al. Progression of coronary calcium and incident coronary heart disease events: MESA (Multi-Ethnic Study of Atherosclerosis). J Am Coll Cardiol. 2013;61(12):1231-9. Progression of coronary calcium and incident coronary heart disease events: MESA (Multi-Ethnic Study of Atherosclerosis)
Evidence overview for CAC Score (Coronary Calcium) Longevity-Medicine Target Ranges