The Skeptical Cardiologist's in 2014 still serves as a good introduction to the test's rationale, procedure, and risks. But in the 5 years since it was published, the body of data published on CAC has expanded substantially and, in 2018, the test was embraced by major organizations.
Overall, I've written 20 posts in which CAC plays a predominant role since then. I feel it's time to put the most important changes and concepts in one spot.
Subclinical Atherosclerosis: What's Your Risk of Dropping Dead?
First, the rationale for using CAC (also known as a coronary calcium score or heart scan) is detection of "subclinical atherosclerosis," a not-so-catchy but hugely important process which I described in an early post on . To recap:
We have the tools available to look for atherosclerotic plaques before they rupture and cause heart attacks or stroke. Ultrasound screening of the carotid artery, as I discussed , is one such tool. Vascular screening is an accurate, harmless and painless way to assess for subclinical atherosclerosis.
In my practice, the answer to the question of who should or should not take aspirin is based on whether my patient has or does not have significant atherosclerosis. If a patient had a clinical event due to atherosclerotic cardiovascular disease (stroke, heart attack, coronary stent, coronary bypass surgery, or documented blocked arteries to the legs) I recommend one 81 milligram (baby) uncoated aspirin daily.
I also recommend a daily baby aspirin (assuming no high risk of bleeding) for patients without a clinical event but significant carotid plaque documented by vascular screening or a high coronary calcium score or incidentally discovered plaque in the aorta or peripheral arteries found by CT or ultrasound done for other reasons.
Help In Deciding Who Needs Aggressive Treatment
Second, CAC is an outstanding tool for further refining risk of heart attack and stroke and helping determine who needs to take statins or undergo aggressive lifestyle reduction, something I described in detail in :
"The updated came out in 2013.
"After working with them for 9 months and using the to calculate my patients' 10 year risk of atherosclerotic cardiovascular disease (ASCVD, primarily heart attacks and strokes) it has become clear to me that the new guidelines will recommend statin therapy to almost all males over the age of 60 and females over the age of 70.
"As critics have pointed out, this immediately adds about 10 million individuals to the 40 million or so who are currently taking statins.
"By identifying subclinical atherosclerosis, CAC scoring identifies those who do or don't need statins."
This is particularly important for patients who have many reservations about statins or who are about taking them when standard risk factor calculations suggest they would benefit.
Although CAC has some similarities to mammography (both utilize low dose radiation, 0.5 mSV), CAC is as the documentary .
What We Can Learn From Donald Trump's CAC?
In 2018, I that "Donald Trump Has Moderate Coronary Plaque: This Is Normal For His Age And We Already Knew It."
What is most notable about the Trump CAC incident is that he, like all recent presidents and all astronauts, underwent the screening. If the test is routine for presidents, why is it not routine for Mr. and Mrs. John Q. Public?
At a minimum we should consider for the general public :
"A three-phased approach to coronary artery disease (CAD) risk assessment is recommended, beginning with initial risk-stratification using a population-appropriate risk calculator and resting ECG. For aircrew identified as being at increased risk, enhanced screening is recommended by means of Coronary Artery Calcium Score alone or combined with a CT coronary angiography investigation."
Guidelines Take A Giant Step Forward
In late 2018, I noted that :
"I was very pleased to read that the newly updated AHA/ACC lipid guidelines (full PDF available here) emphasize the use of CAC for decision-making in intermediate risk patients."
"For those patients aged 40-75 without known ASCVD whose 10 year risk of stroke and heart attack is between 7.5% and 20% (intermediate, see here on using risk estimator) the guidelines recommend 'consider measuring CAC.'"
"If the score is zero, for most consider no statin. If score >100 and/or >75th percentile, statin therapy should be started."
A Few Final Points On CAC
First, it's never too early to start thinking about your risk of cardiovascular disease. I have been using CAC more frequently in the last few years in individuals younger than 40 with a strong family history of early sudden death or heart attack and often we find very abnormal values. See for my discussion on CAC in the youngish from earlier this year.
This image shows a coronary calcium scan with post-processing on a 45-year-old, white male with strong history of premature heart attacks in mother and father. The pink indicates the bony structures of the spine at the bottom and of the sternum at the top. Extensive calcium in the LAD coronary artery is highlighted in yellow and in the circumflex coronary artery in teal. His score was 201, higher than 99% of white male his age.
As I wrote before: "Included in my discussions with my patients with premature ASCVD is a strong recommendation to encourage their brothers, sisters and children to undergo a thoughtful assessment for ASCVD risk. With these new studies and the new ACC/AHA guideline recommendations if they are age 40-75 years there is ample support for making CAC a part of such assessment.
"Hopefully very soon, CMS and the health insurance companies will begin reimbursement for CAC. As it currently stands, however, the $125 you will spend for is money well spent."
The Importance of Proactivity
"If you want to be proactive about the cardiovascular health of yourself or a loved one, and evaluate your risk. Ask your doctor if a CACS will help refine that risk further," I recently wrote.
There are many other questions to answer with regard to CAC: Should they be repeated? How do statins influence the score? Is there information in the scan beyond just the score that is important? Is a scan helpful after a normal stress test?
I've touched on some of these in the past, including the really tough question "
Like most things in cardiology, we have a lot to learn about CAC. There are many more studies to perform. Many questions yet to be answered.
A study showing improved outcomes using CAC-guided therapy versus non-CAC-guided therapy would be nice. However, due to the long time and thousands of patients necessary, it is unlikely we will have results within a decade.
I don't want to wait a decade to start aggressively identifying who among my patients is at high risk for sudden death. You only get one chance to stop a death.
is a private practice noninvasive cardiologist and medical director of echocardiography at St. Luke's Hospital in St. Louis. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at , where a version of this post first appeared.