Calcium Score (Heart Scan): What You Need To Know
New Interest in a (Very) Old Test
A calcium score or heart scan or CAC is not a new test. In fact, it’s a very old test that has been available since 1980. In 2005 the calcium score was already outdated with the advances in cardiac CT angiography.
Over 25 years ago, when I started practicing in Hawaii, I recommended to asymptomatic patients or those who had a negative stress test but who had risk factors of HTN, hypercholesterolemia, diabetes, smoking, or family history of heart disease--to consider paying for a calcium score or heart scan--as a part of their preventive evaluation.
In those days, a calcium score (CAC) was considered a ‘rich and famous’ person’s test. For example, if you were the President of the US, had a private jet at the airport, the CEO of fortune 500 company, owned a bank or were a celebrity—you’d get a calcium score. Because the calcium score wasn’t covered by insurance, only the very wealthy would consider paying the ‘high’ $400 cost.
In the past decade and half, the somewhat antiquated calcium score fell out of the limelight and would cost around $50 dollars in most cities. In Hawaii, our hospitals charge around $100-150 dollars, unfortunately.
Note: As of October 2019, certain private insurance carriers began authorizing calcium scores. This was not preventive reasons, but their hope was to demonstrate a patient had no CAD and, therefore, would not quality for more expensive cholesterol medications known as PCSK9 inhibitors.
What is a Calcium Score?
I have previously discussed what a calcium score is and what role it plays in statin and aspirin use on other posts, so there’s no need to repeat that here. This is an excellent overview on the CAC from the Mayo Clinic.
There is also an excellent summary and video by a colleague of mine Dr. Matt Budoff (Chief of UCLA/Harbor) discussing the role of the calcium score and statin use/predicting future risk of cardiac events. (Click here). Dr. Budoff is the leading authority on calcium scoring and cardiac CT imaging.
Predicting Future Risk of a Heart Attack
The calcium score is only for patients without symptoms. The calcium score has no role if you have angina.
Be sure you understand the difference on how cardiologists evaluate symptomatic vs. asymptomatic patients.
In the asymptomatic patient, the CAC helps predicts future risk for a cardiac event (heart attack, stent, CABG, cardiac death). This is known as risk stratification.
I previously outlined the 6 tests that cardiologists use to evaluate for CAD in the symptomatic patient, so I won’t repeat that here. (Please refer to my post on ‘How Cardiologists Evaluate Chest Pain’). These same 6 tests are used in asymptomatic patients for stratification.
Calcium Score vs. Other Predictors of Cardiac Events: LDL Sub-fractionation or CIMT?
The calcium score is the most accurate method of determining if you have heart disease or not.
It is superior to blood tests such as LDL sub-fractionation and CIMT (carotid intimal medial thickness) studies.
Both LDL sub-fractionation (including CRP, lp(a), homocysteine and CIMT are routinely performed as a part of programs such as MDVIP, yet both are inferior to the calcium score and they often cost more.
For many, many decades doctors have been trying to find biological markers (biomarkers in the blood) that can predict which asymptomatic patient is going to have a heart attack. (See my post on Bernie Sanders.)
In the future, tools such as genetic testing will be used for what is known as ‘personalized medicine’.
As of 2020, the simple, old-fashioned calcium score is the most accurate (sensitive) means for detecting CAD. Everything else is second place.
How the Calcium Score Integrates with Stress Testing
So let’s recap.
For the asymptomatic patient with risk factors for CAD (HTN, hypercholesterolemia, smoking, family history, etc.); men over 45 and women over 50—the calcium score is used to further stratify risk for future cardiac events and determine appropriate physiologic (stress) testing including the necessity for statin/asa therapy.
If you have no CAD, calcium score is zero, then you don’t need statins, aspirin. If your stress test is negative you don’t even need a cardiologist.
If you have a small amount of CAD, a low CAC, statins and aspirin are recommended, but there are options given your risk of cardiac complications are much lower. Annual follow ups and less frequent surveillance testing would be recommended.
If you have a high calcium score, then your treatments and evaluation are upscaled.
Detecting CAD in the Asymptomatic Patient: Calcium Scoring and TSA.
To better help you understand how cardiologists integrate the various of tests in a preventive evaluation, I like to use a TSA/airport security analogy. Pretend for a moment that you are a passenger making your way through airport security. Your cardiologist is like a TSA screener.
The role of the TSA agent is to make sure you are not carrying a weapon or a bomb.
Your cardiologist needs to make sure your heart is not a ‘ticking time bomb’.
The TSA screener asks questions about your bags, reviews documents—looking for nefarious activity. The cardiologists inquires about risk factors and then uses a risk calculator to determine the extent of your evaluation and what interventions you need. (See my post on Cholesterol).
The Calcium Score/Heart Scan is akin to a metal detector. It doesn’t tell you the severity of blockages but only determines the burden of heart disease. The higher the burden, the higher the risk (MESA Trial). An excellent summary of the utility of the calcium score is found here.
Based upon the amount of heart disease you have, the cardiologists then chooses the most appropriate stress test. Stress Testing is basically a ‘pat down’ or ‘frisk’. If your risk for CAD is low, you can get a low- level test. If you risk is high, you will have a higher version of ‘pat down’ aka stress testing performed.
The CCTA would be like the CT scanner at TSA where you hold your hands above your head. This is the most accurate of the noninvasive tests.
Since 1980, it is obvious that cardiologists have been performing the ‘wrong test’ on the asymptomatic patient.
Rather than starting with a stress test, we should have performed a calcium score. Based upon the calcium score, the complexity of the stress test would be chosen.
In fact, the 2009 Appropriate Use Criteria for Nuclear Imaging reiterates that patients who have a high CAC should have higher forms of testing.
Better Late Than Never....40 Years Late!
November 2018: In the 2018 Cholesterol Management Guidelines, for the first time, both societies advocated the calcium score. In other words, it has taken 38 years for the AHA/ACC to admit the benefits of the calcium score. Talk about being late to the party!
October 2019: Blue Cross/Blue Shield announces coverage for the calcium score.
What are the Limitations of a Calcium Score?
A calcium score is only a screening tool. It should not be used for symptomatic patients. If you have symptoms you either need a stress test, CCTA or cardiac catheterization. There is no role for a CAC in the ER, for example.
If you are younger in age, you may not have developed calcified plaques. If so, even a calcium score of 0 may be misleading giving you a false sense of security. That is why I typically favor calcium scoring to be performed in ‘older’ individuals.
A CAC is not a stand-alone test for most people.
How Do I Suggest Evaluating the Asymptomatic Patient (M>45 F>50) with Intermediate/high Pretest likelihood for CAD?
Perform a calcium score prior to stress testing.
If you have a high calcium score, for example CAC>400, a higher level of testing (e.g. nuclear imaging or stress MRI) would be indicated.
If you have a low calcium score (or a zero calcium score), than a simple form of stress testing (for example, a stress echo) may suffice.
The need for aspirin and cholesterol medications would be dictated by the calcium score. (See my posts on how cardiologists determine if you should be on aspirin or cholesterol medications for further information).
Gregg M. Yamada MD FACC
Disclaimer: I hope you find my medical blogs to be educational, pertinent, interesting, and thought provoking. The information provided is educational and should not be taken as medical advice. I am a doctor, but I am not your doctor. Please schedule an appointment with your doctor to discuss these issues and to determine what is right for you.
© 2020. Gregg M. Yamada, MD FACC. All rights reserved