Tag Archives: coronary calcium scan

How Common Are Inaccurate Coronary Artery Calcium Scans?

One reason the  skeptical cardiologist has been so enthusiastic about coronary calcium (CAC) scans is that I have found them to be highly reproducible and highly accurate.

Unlike most  imaging tests in cardiology if we perform a CAC on the same individual in the CT scanner of hospital A and then repeat it within a few days in the CT scanner of hospital B we expect the scores to be nearly identical.

Also, unlike most other imaging tests we don’t expect false negatives or false positives. If the CAC score is zero there is no coronary calcification-high sensitivity. If the score is nonzero there is definitively calcium and therefore atherosclerotic plaque in the coronaries-high specificity.

This is  because calcium as defined in the Agatson score is literally black and white-a pixel is either above or below the cut-off. Computer software automatically identifies on the scan. A reasonably trained CT tech should be able to identify the calcium that is residing in the coronary arteries based on his or her knowledge of the coronary anatomy as registered on CT slices. Using software the total Agatson score is calculated.

A physician reader (either cardiologist or radiologist) (who should have a very good understanding of the cardiac and coronary anatomy ) should review the CT techs work and verify accuracy.

A recent case report, however, has demonstrated that the above  assumptions are not always true.

Franz Messerli, a pre-eminent researcher in hypertension and a cardiologist describes in fascinating detail a false-positive CAC scan he underwent in 2013.  He was told he had a score of 804 putting him in a high risk category consistent with extensive plaque formation.

After consulting with cardiologist friends and colleagues he decided to put himself on a statin and aspirin despite having an excellent lipid profile.

Messerli assumed that the CAC score was not a false positive (although later in his article he indicates he had questioned the reading) writing:

“although one can always quibble with ST segments or wall motion abnormalities, on the CAC the evidence is rock-hard, you actually with your own eyes can see the white calcium specks! ‘Individuals with very high Agatston scores (over 1000) have a 20% chance of suffering a myocardial infarction or cardiac death within a year’—although I did not quite classify, this patient information coming from esteemed Harvard cardiology colleagues3 was hardly reassuring.

(His reference 3 for the 20% risk of MI or cardiac death in a year for CAC score >1000 is suspect. It is a 2003 “patient page” on coronary calcium in Circulation which does not have a reference for that statistic.)

A more recent study found patients with extensive CAC (CAC≥1000) represent a unique, very high-risk phenotype with CVD mortality outcomes (0.80%/yr) commensurate with high-risk secondary prevention patients (0.77%/yr) from the FOURIER trial)

Six years after the diagnosis Messerli was at a Picasso exhibition, “leisurely ambling between his Blue and Pink Period “when he developed chest pain.

To further evaluate the chest pain he underwent a coronary CT angiogram and this demonstrated pristine and normal coronary arteries, totally devoid of calcium.

He did have a lot of mitral annular calcification (MAC). The CCTA images below show how close the MAC is to the left circumflex coronary artery (LCX).


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The slice above shows how the MAC would appear on the CT scan designed to assess coronary calcium.  It’s position is very close to that of the circumflex but an experienced reader/tech  should have known this was not coronary calcification.

MAC is a very common finding on echocardiograms, especially in the elderly and it is likely that this error is not an isolated one.

Dr. Messerli writes

After relating these findings to the cardiologist who did the initial CAC, he indicated that most likely someone mistook mitral annular calcification as left circumflex calcium. This was hardly reassuring, since I specifically had asked that obvious question after receiving the initial CAC

Around the time I read Messerli’s case report I encountered a similar, albeit not as drastic case. A CAC scan showed a significant area of calcification near the left circumflex coronary artery which was scored as circumflex coronary calcification.

image001

The  pattern of this calcification is not consistent with the known path of the circumflex coronary in this case. When it was eliminated from the scoring the patient had a zero score. The difference between a nonzero score and a zero score is hugely significant but for patients with scores >100 such errors are less critical.

I have also encountered cases where extracardiac calcium mimics right coronary calcification.

There are some important take-home points from my and Dr. Messerli’s experience.

  1. False positive CAC scans do occur. We don’t know the frequency. If the scans are not overread by a competent cardiologist or radiologist with extensive experience in cardiac CT these mistakes will be more common

When I asked Dr. Messerli about this problem he responded

I am afraid you are correct in that CAC scores are generated by techs and radiologists and cardiologist simply sign the report without verifying the data. Little doubt that MAC is most often missed.
     2. Like other cardiac imaging tests (such as echocardiography) having an expert/experienced/meticulous  tech and reader matters.
    3. Dr. Messerli and I agree that a research project should be done to ascertain how often this happens and to evaluate the process of reading and reporting CAC.
4. Patients should look at the breakdown of the calcium in the CAC by coronary artery. Whereas it is not uncommon to see most of the calcium in the LAD it is rare to see a huge discrepancy in which the circumflex coronary artery score is very high and the LAD score zero. Such a finding should warrant a review of the scan to see if MAC was included in error.
Skeptically Yours
-ACP
N.B. Dr. Messerli’s report can be read for free and makes for entertaining reading.
I was very intrigued by two comments he made at the end:
  1. “Had my CHD been diagnosed a decade earlier, guidelines might well have condemned me to taking beta-blockers for the reminder of my days.6 This, as Philip Roth taught us in ‘The Counterlife’, might have had rather unpleasant repercussions.7

Until recently I had never read anything by Philip Roth but when he died last year I read his Pulitzer Prize winning  1987 novel American Pastoral and liked it. Given this Roth reference involving beta-blockers I felt compelled to get my hands on “The Counterlife.” The book is a good read (much better IMHO than American Pastoral) and one of the main plot points relates to the side effects (see my post on feeling logy) a character suffers from a beta-blocker. Stimulated by a desire to be able to perform sexually if taken of the medication, the character undergoes coronary bypass surgery and dies.

2. “As stated by Mandrola and true in the present case, ‘given the (lucrative) downstream testing that often occurs when coronary calcium is found in asymptomatic people, the biggest winners from CAC screening may be the testers rather than the tested’.”

I feel the CAC in the right hands should not lead to (lucrative or inappropriate) downstream testing in the asymptomatic (see my discussion on this topic here.)

 

 

The Ultimate Guide To The Coronary Artery Calcium Scan (Score) Circa 2019

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 coronary calcium score or 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”.

The updated AHA/ACC Cardiovascular Prevention Guidelines came out in 2013.

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.


The Widowmaker

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.)

coronary calcium scan with post-processing on a 45 year old white male with very strong history of premature heart attacks in mother and father. The pink indicates the bony structures of the spine (bottom) and the sternum (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.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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.

Apothanasically Yours,

-ACP


 

Donald Trump Has Moderate Plaque Buildup In His Coronary Arteries and his Risk For A Cardiac Event Is Seven Times Hilary Clinton’s Risk

Donald Trump recently appeared on the Dr. Oz show and handed a letter to the celebrity medical charlatan and TV host, Mehmet Oz.

The letter was written by his personal physician , Dr. Harold Bornstein,  screen-shot-2016-10-04-at-3-21-11-pm
and summarized various  laboratory and test  results which led Bornstein to conclude  that Mr. Trump is in excellent health (Bornstein did not repeat his earlier, bizarre statement that “If elected, Mr. Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency.”)

From a cardiovascular standpoint the following sentence stood out:

“His calcium score in 2013 was 98.”

Regular readers of the skeptical cardiologist should be familiar with the coronary calcium scan or score (CAC) by now.  I’ve written about it a lot (here, here, and here) and use it frequently in my patients, advocating its use to help better assess certain  patient’s risk of sudden death and heart attacks.

coronary calcium
Image from a patient with a large amount of calcium in the widowmaker or LAD coronary artery (LAD CA).

The CAC scan utilizes computed tomography (CT)  X-rays, without the need for intravenous contrast, to generate a three-dimensional picture of the heart. Because calcium is very apparent on CT scans, and because we can visualize the arteries on the surface of the heart that supply blood to the heart (the coronary arteries), the CAC scan can detect and quantify calcium in the coronary arteries with great accuracy and reproducibility.

Calcium only develops in the coronary arteries when there is atherosclerotic plaque. The more plaque in the arteries, the more calcium. Thus, the more calcium, the more plaque and the greater the risk of heart attack and death from heart attack.

What Does Donald’s Trump’s Calcium Score Tell Us About His Risk Of A Major Cardiac Event?

We know that, on average, even if you take a statin drug (Trump is taking rosuvastatin or Crestor), the calcium score goes up at least 10% per year which means that 3 years after that 98 score we would predict Trump’s calcium score to be around 120.

Based on large, observational studies of asymptomatic patients, Calcium scores of 101 to 400 put a patient in the moderately high risk category for cardiovascular events.

When I read a calcium score of 101-400, I make the following statements (based on the most widely utilized reference from Rumberger

This patient has:

-Definite, at least moderate atherosclerotic plaque burden

-Non-obstructive CAD (coronary artery disease) highly likely, although obstructive disease possible

-Implications for cardiovascular risk: Moderately High

Patients in this category have a 7-fold risk of major  cardiac events (heart attack or death from coronary heart disease) compared to an individual with a zero calcium scorescreen-shot-2016-10-04-at-3-16-25-pm

 

 

Clinton versus Trump: Zero is Better

Since we know that Hillary Clinton recently had a calcium scan with a score of zero, we can estimate that Trump’s risk of having a heart attack or dying from a cardiac event is markedly  higher than Clinton’s.

Clinton, born October 26, 1947 is 68 years old and we can enter her calcium score into the MESA calcium calculator to see how she compares to other women her age. A  coronary calcium score of 6 is at the 50th percentile for this group.

Interestingly, Trump’s score of 98 at age 67 years was exactly at the 50th percentile. In other words half of all white men age 67 years are below 98 and half are above 98, creeping into the moderately high risk  category.

(This should not be surprising, I touched on the high estimated cardiovascular risk of all aging men in my post entitled “Should all men over age sixty take a statin drug?”)

So, based on his coronary calcium score from 2013, Donald Trump has a  moderate build up of atherosclerotic plaque in his coronary arteries and is at a seven-fold higher risk of a cardiac event compared to Hilary Clinton.

Let the law suits and tweets begin!

Electorally Yours,

-ACP