What Does My Calcium Score Mean?
Coronary artery calcification (CAC) is pathognomonic (specifically characteristic) for coronary artery atherosclerosis (plaquing). The calcified component represents about 20% of the overall plaque.
Testing for the presence of coronary artery calcification by way of a non-contrast CT scan with Agatston score is appropriate for adults at intermediate risk as well as low risk individuals with a family history of premature heart disease. It allows for more personalized risk assessment, rather than extrapolating population data composed of risk factors to the individual.
CAC Agatston Scoring
(Reference: Quantification of coronary artery calcium using ultrafast computed tomography | Journal of the American College of Cardiology
0: None
1-10: Minimal
11-100: Mild
101-300: Moderate
> 300: Severe
> 1000: Very severe
The power of 0:
A score of 0 imparts a very low risk, with a 10 year event rate of 1.1-1.7% (Circ Cardiovasc Imaging 2012;5:467–73). CAC testing can therefore prevent the overtreatment in up to 50% of individuals where traditional risk calculators would have otherwise directed towards treatment with statin therapy. The time-frame for repeat scanning is unclear, but a repeat scan at 5 years seems to provide additional value, as those with 2 consecutive "0" scores have the lowest risk. However those with other high risk features, to include strong family history, may consider shorter intervals at 3-5 years.
Score 1-100:
In MESA, individuals with a calculated 10 year risk of a cardiovascular event between 5 and 7.5% (borderline for considering a statin) with any CAC score > 0 was associated with a risk > 7.5% (above the threshold for statin benefit). Therefore, the presence of any calcification in this group may justify treatment with lipid lowering therapy using a statin (J Am Coll Cardiol 2015;66:1657–68).
Score > 100:
This is considered to be a "coronary artery disease risk equivalent", meaning your 10-year risk of a future cardiovascular event is equivalent to someone who has already suffered an event (secondary prevention). Such individuals may benefit from lowering LDL-C < 70 mg/dL or even lower (< 55 mg/dL) by some guidelines (Circulation 2014;129: 77–86). Symptomatic individuals ought to be considered for nuclear stress imaging.
Score >220: may warrant more aggressive blood pressure goals, as it identifies patients with "SPRINT-equivalent risk." SPRINT Trial: A Randomized Trial of Intensive versus Standard Blood-Pressure Control | New England Journal of Medicine
Score > 300:
This represents severely elevated cardiovascular risk. In the large multinational CONFIRM registry, CAC scores > 300 imparts equivalent risk for ASCVD events as heart attack survivors, which was 9% over 4 years (When Does a Calcium Score Equate to Secondary Prevention?)
Experts recommend utilization of secondary prevention measures in such patients. This includes high intensity lipid lowering therapy aimed at > 50% LDL-C reduction from baseline and threshold LDL-C < 55 mg/dL (< 40 mg/dL for "extreme" risk patients, defined as secondary prevention with multiple additional risk factors), nonHDL-C < 80 mg/dL. NonHDL-C should be employed for any patient with triglycerides (TG) > 150 mg/dL. Apolipoprotein B or "Apo B" is considered to be at least an equivalent or superior biomarker to either LDL- C or nonHDL-C and should be treated to a level < 60 mg/dL (< 50 mg/dL in extreme risk patients).
Score > 400:
Very high risk. Very high annual event rate of 4.8%. Up to 35% of such individuals have been found to have an abnormal stress test, despite the absence of symptoms. Nuclear stress imaging should be considered in such patients. (J Nucl Cardiol 2011;18:700–11).
Diffuse CAC:
For a given CAC score, a more diffuse CAC distribution (2 or 3 coronary involvement vs. 1 coronary) is associated with higher risk The National Lipid Association scientific statement on coronary artery calcium scoring to guide preventive strategies for ASCVD risk reduction
High Left Main CAC:
"for a given CAC score, greater left main CAC predicts risk beyond the total CAC score, particularly when > 25% of the total score" and "should generally be viewed as an additional factor favoring more aggressive preventive pharmacotherapy." The National Lipid Association scientific statement on coronary artery calcium scoring to guide preventive strategies for ASCVD risk reduction
MESA Percentile Rank:
This is derived from the National Heart Lung and Blood Institute's MESA (Multi-Ethnic Study of Atherosclerosis) CAC Score Reference Values database. This is a percentile that compares you to other individuals of the same age, gender and race. MESA Calcium Calculator
> 75th: High risk, regardless of CAC score. It represents premature coronary artery disease. (Differences in prevalence and extent of coronary artery calcium detected by ultrafast computed tomography in asymptomatic men and women)
> 90th: Very high risk with an annual event rate of 6.5%.
Does calcification mean I have a blockage?
Although calcification increases with age, it has been developing for several decades.
While CAC is essentially definitive for the detection of coronary atherosclerosis, it does not always indicate that there is a blockage in a major artery large enough to create a drop in blood flow to the heart muscle tissue. A 70% blockage in the diameter of a major coronary artery is usually required to cause one to have symptoms of chest discomfort, tightness, shortness of breath or other limiting symptoms with exertion (angina). A 90% diameter blockage may cause such symptoms at rest.
While major blockages are important to diagnose, studies have shown that younger patients admitted to the hospital for their "first heart attack" were the result of rupture from a "nonobstructive" plaque (< 70%). The majority of such patients would not have met criteria for placement on prevention therapy based upon conventional risk calculators lacking coronary artery calcium score input. Presently there is no reliable clinical test for detecting such "vulnerable plaque". However, coronary artery calcium score testing, when added to conventional risk calculators, has been shown to improve our ability to "reclassify" an individual's risk for such events better than any other available screening tool.
Do I need to take Aspirin?
In MESA, in those free of diabetes a CAC = 0 predicted net harm with aspirin. Conversely, a CAC > 100 predicted net benefit, regardless of risk factors. The Society of Cardiac CT recommends consideration of aspirin for all with CAC >100. Circ Cardiovasc Qual Outcomes 2014;7: 453–60.
What about Repeat Testing?
The National Lipid Association scientific statement on coronary artery calcium scoring to guide preventive strategies for ASCVD risk reduction coronary artery calcium (CAC) scoring may be repeated in 3 years to assess for accelerated progression (>20-25% per year) and/or an increase to >300, findings that favor more aggressive lipid lowering (Class IIb recommendation).
Do I need to see a specialist?
As with all such studies we recommend discussing these results with your primary care or ordering provider. If specialty services are recommended, Summit Medical Group has a cardiology department offering general and preventive cardiology services to include a board certified Clinical Lipidologist.
