The skeptical cardiologist’s first post on coronary artery calcium (CAC) scan was posted in 2014 and had the wordy title “Searching for Subclinical Atherosclerosis: Coronary Calcium Score-How Old Is My Heart?”
This post still serves as a good introduction to the test (rationale, procedure, risks) but in the 5 years since it was published there has been a substantial body of data published on CAC and in 2018 it was embraced by major organizations.
Overall, I’ve written 20 posts in which CAC plays a predominant role since then and I feels it’s time to put the most important changes and concepts in one spot.
Detection Of Subclinical Atherosclerosis: What’s Your Risk of Dropping Dead?
First, the rationale for using CAC (also known as a heart scan) is detection of “subclinical atherosclerosis”, a non-catchy but hugely important process which I describe in an early post on who should take aspirin to prevent heart attack or stroke:
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 here, 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 they have had a clinical event due to atherosclerotic cardiovascular disease (stroke, heart attack, coronary stent, coronary bypass surgery, documented blocked arteries to the legs) I recommend they take one 81 milligram (baby) uncoated aspirin daily. If they have not had a clinical event but I have documented by either
- vascular screening (significant carotid plaque)
- coronary calcium score (high score (cut-off is debatable, more on this in a subsequent post)
- Incidentally discovered plaque in the aorta or peripheral arteries (found by CT or ultrasound done for other reasons)
then I recommend a daily baby aspirin (assuming no high risk of bleeding).
Help In Deciding Who Needs Aggressive Treatment
Second, CAC is an outstanding tool for further refining risk of heart attack and stroke and helping better determine who needs to take statins or undergo aggressive lifestyle reduction, something I described in detail in my post “Should All Men Over Sixty Take a Statin Drug”.
After working with them for 9 months and using the iPhone app 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 “on the fence” about taking them when standard risk factor calculations suggest they would benefit.
In 2015 I wrote about a documentary entitled “The Widowmaker” (see here and here) which is about the treatment and prevention of coronary artery disease and what we can do about the large number of people who drop dead from heart attacks, some 4 million in the last 30 years:
The documentary, as all medical documentaries tend to do, simplifies, dumbs down and hyperbolizes a very important medical condition. Despite that it makes some really important points and I’m going to recommend it to all my patients.
At the very least it gets people thinking about their risk of dying from heart disease which remains the #1 killer of men and women in the United States.
Perhaps it will have more patients question the value of stents outside the setting of an acute heart attack. This is a good thing.
Perhaps it will stimulate individuals to be more proactive about their risk of heart attack. This is a good thing.
Although CAC has some similarities to mammography (both utilize low dose radiation, 0.5 mSV) I concluded that CAC was not “the mammography of the heart” as the documentary proclaims.
What We Can Learn From Donald Trump’s CAC?
In 2018 I noted that “Donald Trump Has Moderate Coronary Plaque: This Is Normal For His Age And We Already Knew It.”
In October, 2016 the skeptical cardiologist predicted that Donald Trump’s coronary calcium score, if remeasured, would be >100 . At that time I pointed out that this score is consistent with moderate coronary plaque build up and implies a moderate risk of heart attack and stroke.
Trumps’ score gave him a seven-fold increase risk of a cardiovascular event in comparison to Hilary Clinton (who had a zero coronary calcium score) .
Yesterday it was revealed by the White House doctor , Ronny Jackson, that Trump’s repeat score was 133.
I was able to predict this score because we knew that Trump’s coronary calcium was 98 in 2013 and that on average calcium scores increase by about 10% per year.
What is most notable about the Trump CAC incident is that Trump, 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 Joe Q Public?
At a mininum we should consider what is recommended for aircrew to 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.
The 2018 guidelines Take A Giant Step Forward
In late 2018 I noted that CAC had been embraced by major guidelines:
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 <40 years with a strong family of early sudden death or heart attack and often we find very abnormal values (see here for my discussion on CAC in the youngish.)
If heart disease runs in your family or you have any of the “risk-enhancing” factors listed above, consider a CAC, nontraditional lipid/biomarkers, or vascular screening to better determine were you stand and what you can do about it.
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 the test at my hospital is money well spent.
The Importance of Proactivity
In “The MESA App-Estimating Your Risk of Cardiovascular Disease With And Without Coronary Calcium Score” I recently wrote that:
If you want to be proactive about the cardiovascular health of yourself or a loved one, download the MESA app and evaluate your risk. Ask your doctor if a CACS will help refine that risk further.
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 “Should All Patients With A High Coronary Calcium Score Undergo Stress Testing?
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 of my patients is at high risk for sudden death. You only get one chance to stop a death.