Tag Archives: CAC

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.)

 

 

Are You Taking A Statin Drug Inappropriately Like Eric Topol Because of the MyGeneRank App?

The skeptical cardiologist was listening to a podcast discussion between Sam Harris and Eric Topol recently and became  flabbergasted.

Topol, the “world-renowned cardiologist” who is seemingly everywhere in media these days was discussing what he considers the overuse of imaging technology during the podcast which Harris’s website describes as follows:

In this episode of the Making Sense podcast, Sam Harris speaks with Eric Topol about the way artificial intelligence can improve medicine. They talk about soaring medical costs and declining health outcomes in the U.S., the problems of too little and too much medicine, the culture of medicine, the travesty of electronic health records, the current status of AI in medicine, the promise of further breakthroughs, possible downsides of relying on AI in medicine, and other topics.

Personally, I have been amazed at the hype and promotion that artificial intelligence (AI) has been getting given the near total absence in cardiology of any tangible benefits from it and I wanted to hear what the man who wrote ” Deep Medicine: How Artificial Intelligence Can Make Healthcare Human Again ” had to say about it.

About 28 minutes into the podcast, Harris, who has lately been preoccupied with promoting meditation as a cure for all ills, begins describing a procedure he underwent:

I’ve had a few adventures in cardiology. CT scan, calcium score scan.

Harris, who in neuroscience and philosophy might speak precisely, here is very vague. Did he get a coronary calcium scan (CAC) or a coronary CT angiogram? There is a huge difference and he is conflating the two imaging procedures.

Apparently he is unhappy with having undergone it but:

I might be telling a different story if my life was saved by it.

And his doctor’s rationale  for getting the scan was lacking:

The way this was dispensed to me. We now have this new tool, let’s use it.

Let me just say at this point that if your doctor’s rationale for performing a test is that he has a machine that performs the test just say no. Or demand an explanation of how the results will change your management or prognosis.

Apparently the scan that Harris had didn’t turn out either horrifically worse than expected or remarkably better and didn’t change management:

In my case at the end it didn’t make sense.

Now, I can forgive Sam Harris for being somewhat naive and misguided when it comes to coronary artery scans or coronary CT angiograms but Eric Topol , the world’s leading talking cardiology head should fully understand the value of coronary artery calcium scans.

This is where I first become flabbergasted.

Topol says in response at this point that coronary artery calcium scans are “terribly overused” and that “I’ve never ordered one.”

Eric, you cannot be serious!

Are you telling me that you wouldn’t order one on your 60 year old airline pilot friend whose father dropped dead of a massive MI at age 50 but whose lipids look fine?

Why doesn’t Eric order CACs?

Because “There are so many patients who have been disabled by the results of their calcium score even though they have no symptoms.”

This is where the degree of my flabbergastment increased by an order of magnitude.

Our job as preventive cardiologists is to identify those at high risk and lead them to lifestyle choices and medicine that dramatically lowers that risk.  We educate them that the large build up of subclinical atherosclerosis we identified does not have to result in sudden death, crippling heart attacks or strokes. We reassure them that with the right tools we can help them live a long, productive and happy life.

Eric, what do you tell these people? The calcium score is irrelevant? You’re fine. You shouldn’t have gotten it. Surely not! This would be the preventive cardiology equivalent of sticking one’s head in the sand.

This is not the first time Topol has opined on the dangers of CAC. An excerpt from his book, ‘The Patient Will See You Now: The Future of Medicine Is in Your Hands” posted on Scientific American describes the ills created in a 58 year old man who had a CAC score of 710.

My patient was told that he had a score of 710—a high calcium score—and his physician had told him that he would need to undergo a coronary angiogram, a roadmap movie of the coronary anatomy, as soon as possible. He did that and was found to have several blockages in two of the three arteries serving his heart. His cardiologists in Florida immediately put in five stents (even though no stress-test or other symptoms had suggested they were necessary), and put him on a regimen of Lipitor, a beta-blocker, aspirin and Plavix.

This case is not an example of inappropriate usage of CAC it is an example of really bad doctoring and failure to utilize the CAC information properly.

One should never order a cardiac catheterization/coronary angiogram solely on the basis of a high CAC score. Even ordering a stress test in this situation is debatable as I discuss here.

And Topol’s patients symptoms were most likely related to a beta-blocker that he didn’t need (see here).

My Gene Rank

Later in the podcast I reached maximum flabbergast  levels when Topol announced that as a result of a high score for CAD risk he received using an iPhone app called MyGeneRank he had started taking a statin drug.

He enthusiastically promoted the app which his Scripps Translational Science Institute developed and urged listeners to utilize this approach to better refine the estimate of their risk of heart attack and stroke.

Per the Scripps website:

The MyGeneRank mobile app is built using Apple’s ResearchKit, an open source framework that enables researchers and programmers to build customized mobile apps for research purposes. With user permission, the app connects with the 23andMe application program interface and automatically calculates and returns a genetic risk score for coronary artery disease.

In addition, the app calculates a 10-year absolute risk estimate for an adverse coronary event, such as heart attack, using a combination of genetic and clinical factors. Users are able to adjust behavioral risk factors to see the influence of lifestyle habits on their overall risk.

Elsewhere, Topol, has stated

“We are excited to launch a unique study that combines an iOS app and genomics to help guide important health decisions,” says Eric Topol, MD, Founder and Director of the Scripps Translational Science Institute and Professor of Molecular Medicine at The Scripps Research Institute. “Not only does participating in the study arm individuals with their own data, but it also gives them the opportunity to participate in new type of research – one that is driven by and for patients.”

Curious, I downloaded the MyGeneRank app, answered some questions and gave it permission to access my 23 and Me data. After requiring me to complete a survey on my health it then  yielded  my coronary artery disease risk score.

 

 

 

 

 

 

 

Oh, no! My genetic risk score was at the 81st percentile! In the red zone.  According to Eric Topol I should take a statin like him. Based on these results I probably should be incredibly anxious and crippled by fears of cardiac death.

Fortunately, I have superior information to allay my fears. I’ve had CAC scans in the past which are well below average for men my age. Despite my dad’s history of early CAD, a recent coronary CT angiogram showed minimal plaque. I know exactly where I stand risk-wise.

How many cardiac cripples has Topol’s MyGeneRank inappropriately created?

Is the data that MyGeneRank utilizes superior to that from CAC scans?

For coronary artery calcium scanning there is a wealth of data supporting improved risk prediction and we are looking directly at the atherosclerotic process that eventually causes the diseases we want to prevent.

It’s interesting that a recent study looking at a polygenetic risk score’s ability to predict cardiac events was comparing the risk score’s ability to predict subclinital atherosclerosis:

Each 1-SD increase in the polygenic risk score was associated with 1.32-fold (95% CI, 1.04-1.68) greater likelihood of having coronary artery calcification and 9.7% higher (95% CI, 2.2-17.8) burden of carotid plaque.

In the Scientific American article Topol quotes Mark Twain:, “To a man with a hammer, a lot of things looks like nails that need pounding.”

Topol’s hammer is artificial intelligence. We eagerly await the day he discovers a nail that he can bang on that  significantly advances medical care.

In the meantime I and the vast majority of progressive preventive cardiologists will be utilizing CAC scores intelligently to identify both those patients at high risk for cardiovascular events who need more aggressive treatment and those at low risk who can be reassured and have treatment de-escalated.

Polygenetic CAD risk scores do show promise to improve our predictive powers but more study is needed in this are before we make clinical treatment decisions based on the results.

Astoundingly Yours,

-ACP

Ilene Has High Cholesterol With A “Wonderful Ratio” And A Branch Retinal Vein Occlusion: Should She Take A Statin?

Recently the skeptical cardiologist was asked by Ilene, a reader with an HDL almost as high as her LDL and a history of branch retinal vein occlusion (BRVO) whether she should take the statin her cardiologist had prescribed.

I enjoy reading your articles and would appreciate your opinion on my situation.  I recently took a lipid panel blood test: total cholesterol: 244 HDL:112 LDL:121 VLDL:11  CRP: 1.77 Triglycerides: 57.  Also my Cardiac Agatston  score is 21.
I had a Branch Retinol Vein Occlusion a year ago in my left eye  (it’s healing beautifully) and as a precaution  am now taking Amlodipine 5mg daily (my blood pressure was never too high to begin with) along with a daily baby aspirin.
I am otherwise a healthy 72 year old woman, exercise and eat healthy.
My regular doctor (Integrative MD) says my cholesterol ratio is wonderful….my cardiologist wants me to take a statin (Atorvastatin) in a low dose.  The ONLY med I take is Amlodipine and I am not one to be taking a plethora of meds for the rest of my life (unless “absolutely” necessary.  What is your suggestion…take a statin or not.
While I can’t provide medical advice to Ilene specifically it is worthwhile  to ponder  the general aspects of her case and how I would approach it as it likely applies to thousands of other patients including many of my own.
In my mind there are two questions here: 1) Should Ilene and patients like her take a statin to prevent future heart attacks and strokes and 2) Do statins  effect the Branch Retinal Vein Occlusion (BRVO)?
Although I’m not a fan of integrative or functional medicine Ilene’s integrative MD is correct in saying that her ratio of total cholesterol to HDL cholesterol is wonderful. Perhaps that high  HDL is protecting her from a build-up of atherosclerotic plaque.
On the other hand, Ilene tells me that  “My father did have a heart attack in his 60’s”.  Perhaps she inherited something from him that puts her in a higher than average risk category.
With the information from the CAC we don’t have to guess about the influence of the high HDL and the family history of CAD. Her score is at the 48th percentile, slightly below average for white women her age, thus it would appear she is not destined for her father’s fate.
Frequent readers of skepcard (especially my posts on statin fence sitters) will know I  plug all these numbers (preferably with the calcium score available) into the MESA coronary calcium risk calculator
In this case, the CAC score does not significantly alter our risk estimate as it is so close to the average for her age
Even if we count her as having hypertension because she is on the amlodipine her 10 year risk of heart attack and stroke is low at 3.2%.
Guidelines don’t recommend statin treatment unless risk is >7.5%.
Also, note that I answered yes to “Family history heart disease” but most studies generally only consider this a risk factor if father had heart attack prior to age 55 years. If we make that a no the risk drops to <3%.
Now that we’ve answered Ilene’s real question let’s see if the BRVO warrants statin therapy.
Branch Retinal Vein Occlusion
BRVO is the blockage of a vein from the retina and the second most
common cause of vision loss from retinal vascular disease, following diabetic retinopathy. It typically  results in the painless loss of vision in one portion of one eye due to hemorrhage and edema in the retina.
A reasonable summary of BRVO provided by the American Academy of Ophthalmology can be found here.
BRVO is not clearly related to atherosclerosis or hyperlipidemia and there is no evidence that taking a statin would prevent recurrence or help the condition.

The leading theory for what causes BRVO is that the more delicate and distensible retinal veins are squished or compressed at points where the stiffer and thicker retinal arteries cross them.  Up to Date notes:

Whereas branch retinal vein occlusion (BRVO) appears to be related to compression of the branch vein by retinal arterioles at the arteriovenous crossing points, central retinal vein occlusion (CRVO) is usually associated with primary thrombus formation.

Although BRVO is more common in patients with hypertension and atherosclerosis it is not clear that one causes the other or that treatment of hypertension or atherosclerosis diminishes the risk of BRVO.  So statins are not recommended.
More Questions
Every patient case for me leads to more questions,  more investigations and more knowledge. Here are some questions that occurred to me from ilene’s case.
-Why would someone with no symptoms and no heart problems be seeing a cardiologist?
(“I started seeing a cardiologist just to make sure all systems were “go” and stayed that way!… we take care of our cars so why not my body. )
I kind of like this answer and I definitely see lots of patients with that philosophy but if we extrapolate the car analogy: going to a cardiologist would be like taking your car to a mechanic who only works on engines or perhaps one specific part of the engine (help me out here people who know about cars.)
-Why was Ilene unwilling to take a statin? (I pretty much know the answer to this (see here) for most patients.
‘m just afraid of the horrible muscle related side effects of statin drugs…and that’s why I’m taking Berberine 500mg twice a day.
Yep. I feel a post abut Berberine may be in the works!
-Finally, should a 72 year old with a CAC score of 21 and BRVO be taking a baby aspirin?
I’ve generally advocated aspirin in primary prevention for scores >100  so wouldn’t advise it for prevention of cardiovascular events in this situation.
In addition, I have seen nothing in the literature that recommends aspirin for BRVO. These two BRVO experts do not recommend either aspirin or anticoagulants.
Proretinally Yours,
-ACP
N.B. If you have a blockage of the the artery that supplies blood to the retina or a branch retinal artery occlusion ( BRAO)
you might benefit from a statin as this is often caused by a clot or plaque flying out of the heart or the carotid artery.

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


 

A Voodoo Coronary Calcium Scan Could Save Your Life

The skeptical cardiologist received this reader comment recently:

So I went and got a Cardiac Calcium Score on my own since my cardiologist wouldn’t order one because he says they are basically voodoo.. Family History is awful for me.. I got my score of 320 and I’m 48 years old.. Doc looked at it and basically did the oh well.. so I switched docs and the other doc basically did the same thing.. I try so very hard to live a good lifestyle..I just don’t understand why docs wait so long to actually take a look at your heart.. I would have thought a score of 320 would have brought on more testing.. It did not..

I was shocked that a cardiologist practicing in 2019 would term a coronary artery calcium (CAC) scan (aka, heart scan or calcium score) “voodoo.”

I’m a strong advocate of what I wrote in a recent post with the ridiculously long title, “Prevention of Heart Attack and Stroke-Early Detection Of Risk Using Coronary Artery Calcium Scans In The Youngish“:

It’s never too early to start thinking about your risk of cardiovascular disease. 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 where you stand and what you can do about it.

Here’s what I told this young man:

If your cardiologist tells you coronary calcium scores are voodoo I would strongly consider changing cardiologists.

A score of 320 at age 48 puts you in a very high risk category for stroke and heart attack over the next 10 years.

You need to find a physician who understands how to incorporate coronary calcium into his practice and will help you with lifestyle changes and medications to reduce that risk


Let’s analyze my points in detail and see if these off the cuff remarks are really justified

1,  Changing cardiologists.

Recent studies and recent guideline recommendations (see here) all support utilization of CAC in this kind of patient. If you have a strong family history of premature heart disease or sudden death you want a cardiologist who is actively keeping up on the published literature in preventive cardiology,  Such cardiologists are not dismissing CAC as “voodoo” they are incorporating it into their assessment of patient’s risk on a daily basis.

2. High risk of CAC score 320  at age 48

I plugged normal numbers for cholesterol and BP into the MESA risk calculator (see my discussion on how to use this here) for a 48 year old white male.

As you can see the high CAC score puts this patient at almost triple the 10 year risk of heart attack and stroke.

Immediate action is warranted to adjust lifestyle to reduce this risk! This high score will provide great motivation to the patient to stop smoking, exercise, lose excess weight, and modify diet.

Hidden risk factors such as lipoprotein(a),  hs-CRP and LDL-P need to be assessed.

Drug treatment should be considered.

3. Find physician who will be more proactive in preventing heart disease

This may be the hardest part of all my recommendations. On your own you can get a CAC performed and advanced lipoprotein analysis.

However, finding progressive, enlightened, up-to-date preventive cardiologists can be a challenge.

We need a network of such cardiologists.

I frequently receive requests from readers or patients leaving St. Louis for recommendations on cardiologists.

If you are aware of such preventive cardiologists in your area email me or post in comments and I will keep a log and post on the website for reference.

Voodoophobically Yours,

-ACP

Prevention of Heart Attack and Stroke-Early Detection Of Risk Using Coronary Artery Calcium Scans In The Youngish

Since 1/3 of Americans die from atherosclerotic cardiovascular disease (ASCVD, mostly heart attacks and strokes) and dropping dead is often the first symptom of ASCVD it’s incredibly important to identify early, “subclinical” ASCVD and begin measures to reduce risk.

How early to begin that process is open to debate. The recent sudden death of the 41-year old son of a patient of mine, however, has reinforced to me how crucial it is to begin risk assessment and potential treatments as early as possible, especially in individuals with a strong family history of premature ASCVD.

We use standard risk factors like lipids, smoking, age, gender and diabetes to stratify individuals according to their 10 year risk of ASCVD (using this online risk calculator) but many apparent low risk individuals (often due to inherited familial risk) drop dead from ASCVD and many apparent high risk individuals have no subclinical ASCVD and don’t need preventive therapy.

Recent studies provide compelling support for the early utilization of cardiac imaging in to identify high risk individuals.

Heart attacks and most sudden cases of sudden death are due to rupture of atherosclerotic plaques. Thus, it makes sense to seek out  such plaques, a process I call searching for subclinical atherosclerosis. There are a number of ways to search for sublinical plaques but the two most widely studied are carotid ultrasound screening and coronary artery calcification (CAC) measurement.

I’ve been utilizing CAC (also termed  heart scan, coronary calcium score, or cardioscan) to help assess my patient’s risk of ASCVD for years although the procedure is not covered by insurance and until recently was not strongly endorsed by major guidelines. (For a complete description of the test and the risks/benefits see here). As I pointed out here, in November the new ACC/AHA guidelines finally embraced CAC for

adults 40 to 75 years of age without diabetes mellitus and with LDL-C levels ≥70 mg/dL- 189 mg/dL (≥1.8-4.9 mmol/L), at a 10-year ASCVD risk of ≥7.5% to 19.9%, if a decision about statin therapy is uncertain

Typically, if we have calculated (using the ASCVD risk estimator) a 10 year risk >7.5% we have a discussion with the patient about beginning drug treatment to reduce risk.

To inform the decision and help us “get off the fence” I usually recommend a CAC. To see how this works in a typical sixty something see my posts here and here.

Significant Of CAC Score

As the new ACC/AHA guidelines state:

If CAC is zero, treatment with statin therapy may be withheld or delayed, except in cigarette smokers, those with diabetes mellitus, and those with a strong family history of premature ASCVD.

A duo of studies from Walter Reed Army Hospital have provided more support for the value of the zero CAC for risk prediction and identifying who should get treatment for prevention of both heart attacks and strokes.

Over 10,00 subjects underwent CAC and were assessed for the primary outcomes of all-cause mortality, incident MI, stroke, and the combination of major adverse cardiovascular events (MACE), defined as stroke, MI, or cardiovascular death over an average 11.4 years

Patients were classified on the basis of the presence or absence of calcium and further subdivided into CAC score groups of 0, 1 to 100, 101 to 400, and >400

Patients without a zero CAC had a very low number of events , with a 1.0% rate of mortality and 2.7% rate of MACE over a 10-year period.

On the other hand subjects without any traditional risk factors (n = 6,208; mean age 43.8 years), the presence of any CAC (>0) was associated with a 1.7 fold increased risk of MACE after adjustment for traditional risk factors.

f2.large-3
Patients with CAC who were prescribed a statin had a significantly reduced risk of MACE (aSHR: 0.76; 95% CI: 0.60 to 0.95; p = 0.015), whereas patients without CAC had no associated MACE reduction (aSHR: 1.00; 95% CI: 0.79 to 1.27; p = 0.99). p = 0.097 for interaction between statin treatment and CAC presence. aSHR = adjusted subhazard ratio; CAC = coronary artery calcium; CI = confidence interval; MACE = major adverse cardiovascular event(s)

The red line of the >400 score individuals has a much higher risk of death, stroke and heart attack (myocardial infarction) than the blue (CAC 1-100) or the gray line of the zero CAC scorers.

Furthermore, when these investigators looked at outcomes in those individuals who received statins versus those who didn’t, the zeros didn’t benefit from statin therapy over the 10 year follow-up.

f3.large
Benefit of statin therapy was significantly related to CAC group with benefit in patients with CAC score >100 but not in patients with CAC <100. aSHR = adjusted subhazard ratio; CAC = coronary artery calcium; CI = confidence interval; MACE = major adverse cardiovascular event(s).

But there was a tremendous reduction in bad CV events in those with scores >100 who received statin (red line) versus those who did not (blue line).

Here’s the figure which encapsulates both the risk prediction power of the CAC (and the benefits of statin treatment restricted to those with >0 (blue lines)

f2.large-4

 

Benefits of CAC Testing In The Young

So these new studies provide powerful data supporting the use of CAC in younger individuals to help us refine risk estimates and target the individual at high risk of MI and sudden death. It seems highly appropriate to consider CAC testing beginning at age 40 years as the AHA/ACC guidelines suggest.

But what about the individual who has a strong family history of premature CAD and is age say 35 or 39 years of age. Do we ignore advanced risk assessment? Very few individuals die in their 30s from ASCVD but I have a number of patients who suffered heart attacks in their forties. In addition, the earlier we can start risk modification the better as the process begins very early in life and accumulates over time.

The Coronary Artery Risk Development in Young Adults (CARDIA) Study published in 2017 has demonstrated the early development of nonzero CAC score in the youngish and the predictive value of the high CAC score for mid life ASCVD events.  It was  a prospective community-based study that recruited 5115 black and white participants aged 18 to 30 years from March 25, 1985, to June 7, 1986. The cohort has been under surveillance for 30 years, with CAC measured 15 (n = 3043), 20 (n = 3141), and 25 (n = 3189) years after recruitment. The mean follow-up period for incident events was 12.5 years, from the year 15 computed tomographic scan through August 31, 2014.

The conclusions:

Any CAC in early adult life, even in those with very low scores, indicates significant risk of having and possibly dying of a myocardial infarction during the next decade beyond standard risk factors and identifies an individual at particularly elevated risk for coronary heart disease for whom aggressive prevention is likely warranted.

screen shot 2019-01-19 at 12.36.44 pmI read CAC scans every day and it is not uncommon to see a non-zero scores in individuals in their late 30s or early 40s.

The two sons of another one of my patients both in their late 50s with unremarkable risk factor profiles and both developing anginal type symptoms limiting their activities each underwent multi vessel stent procedures in the last month. If I had seen them  10 to 20 years ago we would have identified the subclinical atherosclerosis building up in their coronaries, started treatment and avoided the need for invasive, expensive procedures.

Other Risk-Enhancing Factors To Consider In The Young

The ACC/AHA guidelines list some “risk-enhancing factors” some of which I find useful.

screen shot 2019-01-19 at 7.33.39 am

Clearly family history of premature ASCVD is important but the devil is in the details. What relatives count? What was the event in the family member? If it was sudden death was an autopsy done?

What about nontraditional lipid/biomarkers?  I consider an assessment of Lp(a) and some more sophisticated measurement of atherogenic dyslipidemia (apoB, LDL-P) and inflammation (CRP) essential.

Interestingly the guidelines include ABI (which I do not find helpful) but not carotid vascular screening which has frequently guided me to earlier therapy in youngish individuals with abnormal biomarkers or strong family history.

Vascular screening in young subjects may detect subclinical atherosclerosis as measured by thickening of the carotid wall (IMT) or early carotid plaque prior to the formation of calcium in the coronary arteries. Advanced IMT precedes the formation of soft plaque in arteries and only later is calcium deposited in the plaque.

It’s never too early to start thinking about your risk of cardiovascular disease. 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.

Skeptically Yours,

-ACP

Coronary Artery Calcium Scan Embraced By New AHA/ACC Cholesterol Guidelines: Will Insurance Coverage Follow?

The skeptical cardiologist has been utilizing coronary artery calcium (CAC) scans to help decide which patients are at high risk for heart attacks, and sudden cardiac death for the last decade. As I first described in 2014, (see here) those with higher than expected calcium scores warrant more aggressive treatment and those with lower scores less aggrressive treatment.

Although , as I have discussed previously, CAC is not the “mammography of the heart” it is incredibly helpful in sorting out personalized cardiovascular risk. We use standard risk factors like lipids, smoking, age, gender and diabetes to stratify individuals according to their 10 year risk of atherosclerotic cardiovascular disease (ASCVD) but many apparent low risk individuals (often due to inherited familial risk) drop dead from ASCVD and many apparent high risk individuals don’t need statin therapy.

Previously, major guidelines from organizations like the AHA and the ACC did not recommend CAC testing to guide decision-making in this area. Consequently, CMS and major insurers have not covered CAC testing. When my patients get a CAC scan they pay 125$ out of their pocket.. For the affluent and pro-active this is not an obstacle, however those struggling financially often balk at the cost.

I was, therefore, 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.

I don’t agree totally with this use of CAC but it is a step forward. For example, how I approach a patient with CAC of 1-99 depends very much on what percentile the patient is at. A score of 10 in a 40 year old indicates marked premature build up of atherosclerotic plaque but in a 70 year old man it indicates they are at much lower risk than predicted by standard risk factors. The first individual we would likely recommend statin therapy and very aggressive lifestyle changes whereas the second man we could discuss  taking off statins.

Neil Stone, MD, one of the authors of the guidelines was quoted  as saying that the imaging technique is “the best tiebreaker we have now” when the risk-benefit balance is uncertain.

“Most should get a statin, but there are people who say, ‘I’ve got to know more, I want to personalize this decision to the point of knowing whether I really, really need it.’ … There are a number of people who want to be certain about where they stand on the risk continuum and that’s how we want to use it,”

Indeed, I’ve written quite a bit about my approach to helping patients “get off the fence” on whether or not to take a statin drug.

I recommend reading “Are you on the fence about taking a statin drug” to understand the details of using CAC in decision-making and the follow up post on a compromise approach to reducing ASCVD risk.

Deriskingly Yours,

-ACP

Full title of these new guidelines includes an alphabet soup of organization acronyms

2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol

N.B. For your reading pleasure I’ve copied the section in the new guidelines that discusses in detail coronary artery calcium.

Two interesting sentences which I’ll need to discuss some other time

-When the CAC score is zero, some investigators favor remeasurement of CAC after 5 to 10 years

CAC scans should be ordered by a clinician who is fully versed in the pros and cons of diagnostic radiology.

In MESA (Multi-Ethnic Study of Atherosclerosis), CAC scanning delivered 0.74 to l.27 mSv of radiation, which is similar to the dose of a clinical mammogram 

-4.4.1.4. Coronary Artery Calcium

Substantial advances in estimation of risk with CAC scoring have been made in the past 5 years. One purpose of CAC scoring is to reclassify risk identification of patients who will potentially benefit from statin therapy. This is especially useful when the clinician and patient are uncertain whether to start a statin. Indeed, the most important recent observation has been the finding that a CAC score of zero indicates a low ASCVD risk for the subsequent 10 years (S4.4.1.4-1–S4.4.1.4-8). Thus, measurement of CAC potentially allows a clinician to withhold statin therapy in patients showing zero CAC. There are exceptions. For example, CAC scores of zero in persistent cigarette smokers, patients with diabetes mellitus, those with a strong family history of ASCVD, and possibly chronic inflammatory conditions such as HIV, may still be associated with substantial 10-year risk (S4.4.1.4-9–S4.4.1.4-12). Nevertheless, a sizable portion of middle-aged and older patients have zero CAC, which may allow withholding of statin therapy in those intermediate risk patients who would otherwise have a high enough risk according to the PCE to receive statin therapy (Figure 2). Most patients with CAC scores ≥100 Agatston units have a 10-year risk of ASCVD≥7.5%, a widely accepted threshold for initiation of statin therapy (S4.4.1.4-13). With increasing age, 10- year risk accompanying CAC scores of 1 to 99 rises, usually crossing the 7.5% threshold in later middle age (S4.4.1.4-13). When the CAC score is zero, some investigators favor remeasurement of CAC after 5 to 10 years (S4.4.1.4-14–S4.4.1.4-16). CAC measurement has no utility in patients already treated with statins. Statins are associated with slower progression of overall coronary atherosclerosis volume and reduction of high-risk plaque features, yet statins increase the CAC score (S4.4.1.4-17). A prospective randomized study of CAC scoring showed improved risk factor modification without an increase in downstream medical testing or cost (S4.4.1.4-18). In MESA (Multi-Ethnic Study of Atherosclerosis), CAC scanning delivered 0.74 to l.27 mSv of radiation, which is similar to the dose of a clinical mammogram (S4.4.1.4- 19). CAC scans should be ordered by a clinician who is fully versed in the pros and cons of diagnostic radiology.

Downloaded from http://ahajournals.org by on November 11, 2018

from Grundy SM, et al.
2018 Cholesterol Clinical Practice Guidelines

Is Coronary Calcium Scanning the Mammography of the Heart?

If you have watched The Widowmaker as suggested by the skeptical cardiologist you have likely been convinced that the developers and promoters of coronary artery calcium (CAC) scans, for the early detection of heart disease, are true heroes in the cardiology world.

These members of the “calcium club” are portrayed as unbiased self-less promoters of the prevention of heart attacks and sudden death, fighting an uphill battle against the evil procedure and money-driven forces who push coronary stents-greedy interventional cardiologists and the device, hospital and insurance industries.

A constant theme in the documentary is that CAC scanning should be to the heart what mammography is to the breast. It should be done on all patients over a certain age and should be covered by insurance.

As a non-invasive cardiologist with a strong interest in prevention, I am definitely a strong proponent of CAC scans in the right population. As the skeptical cardiologist, however, I find flaws with the mammography comparison.

Let’s review some of the established science regarding CAC scans.

What Is A CAC Scan?

coronary calcium
Coronary calcium scan from a 52 year old man I was seeing for palpitations. He had had an equivocal stress test but had a strong family history of CAD. Standard risk factors were unremarkable. As shown here, he has very extensive calcium in his coronary arteries. The left anterior descending (LAD) has lots of calcium (CA, indicated by arrows). His total score was 1798 which is at the 99th percentile for caucasian men his age. This means that his score is higher than 99% of caucasian men. Such a high score for age puts him in an extremely high risk category of heart attack and death.

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.

A preventive cardiologist, Dr. Arthur Agatson, who is interviewed in the film (and who is also the creator of the South Beach Diet, a low carbohydrate, high fat diet), developed a method for counting up the amount of calcium in the coronary arteries (the Agatson or calcium score).

Calcium only develops in the coronary arteries when there is atherosclerotic plaque. The more plaque in the arteries, the more calcium.

What Is The Risk Of  A High CAC Score

Multiple observational studies have shown that a high versus low calcium score is indicative of high risk for heart attack and death.

For example, a large study published in 2008 (the MESA study), followed 6,814 individuals for 3.8 years. Compared with patients with a CAC score of 0, patients with a CAC score of 101-300 had a 7.7 fold increase risk of a coronary event (heart attack). CAC score of >300 conferred almost a tenfold increase risk.

Screen Shot 2015-09-06 at 8.32.02 AMBased on data from 5 large studies and almost 15,000 patients, we can put patients with CAC score in very low to high risk categories for cardiac events over the next 10 years.

What Is The Value Of A Zero Calcium Score?

Just as important as identifying patients with advanced or premature atherosclerosis who should be getting intensive therapy  for prevention of cardiac events, is identifying those patients who may not warrant therapy.

A CAC score of zero puts a patient in an extremely low risk category.  A recent study, with the provocative title of:

A 15-Year Warranty Period for Asymptomatic Individuals Without Coronary Artery Calcium

…demonstrated that a zero calcium score confers this low risk of cardiac events for up to 15 years.

Thus, many patients, who are considered intermediate risk based on standard risk factors, do not have significant plaque by CAC score and may not need otherwise indicated statin therapy.

Mammography

The comparison of mammography to CAC scanning is appropriate in that both have created considerable controversy and are at the epicenter of discussions on the value of mass screenings in the prevention of life-threatening disease.

In contrast to CAC, mammography has been widely accepted and promoted by most professional organizations. In recent years, however, the value of mammography for all women over the age of 40 has been questioned.

In 1980, a randomized controlled trial of screening mammography and physical examination of breasts in 89, 835 women, aged 40 to 59, was initiated in Canada. It was called the Canadian National Breast Screening Study.

The findings published last year were:

Annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available. Overall, 22% (106/484) of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial.

Recently, the Swedish Medical Board recommended that all mammography screening be phased out in that country.

The US preventive services task force draft guidelines, updated earlier this year, will recommend screening for women aged 50-74 but not in those aged 40-49 years.

Downsides of breast cancer mammography screening include:

-Over-diagnosis: finding and treating breast cancer that would not have been a threat to the patient.

-False positives: the test identifies a possible cancer which is not subsequently confirmed. False positives lead to breast biopsies, which are not needed and often cause needless anxiety and stress.

-Radiation exposure.

Is CAC Screening The Cardiac Equivalent Of Mammography?

CAC scans differ fundamentally from mammography because atherosclerosis is a continuous and diffuse arterial process, whereas breast cancer is (most often) localized, and either present or not.

The development of atherosclerosis starts with fatty streaks in multiple arterial beds fairly early in life, followed by progressive plaque development with progressive build up of calcium in the plaques.

Thus, the CAC score ranges continuously from zero up to several thousand.

The calcium score is not subject to false positives-if calcium is detected, atherosclerotic plaque is present.

A mammogram is either abnormal, suggesting cancer and requiring a biopsy, or it is normal. There is no continuous grading of risk.

The second fundamental difference in the two disease processes is that atherosclerosis can kill suddenly without warning.

As pointed out in numerous examples in The Widowmaker, an individual can seem fit and hearty one minute, and be dead the next, from a heart attack caused by a lethal abnormal rhythm.

Breast cancer deaths on the other hand, occur slowly after diagnosis, and are generally predictable.

Nuclear Stress Tests are the Mammography of the Heart

If we are looking for a cardiac test that has characteristics similar to mammography, the nuclear stress test is much closer than CAC.

With a nuclear stress test we are using a radio tracer injected intravenously, which subsequently traverses the coronary arteries into the heart muscle. Subsequent imaging of the photons emitted by the radio tracer allows assessment of the status of blood flow down the coronary arteries.

The test is designed to identify coronary arteries with flow limiting blockages (usually >70% blocked), caused by atherosclerotic plaques. Such blockages are more likely to be causing symptoms and therefore more likely to require treatment with coronary stents or bypass surgery.

Like mammography, then, nuclear stress tests are either abnormal or normal, and when abnormal they can be falsely abnormal.

Nuclear stress tests have a very high incidence of false positives. These false positives result in invasive catheterization procedures to more directly image the arteries, and may result in inappropriate coronary stenting or bypass procedures with associated risks.

It is because of the high risk of false positives and attendant harm that in the last decade, all cardiac societies recommend against the routine use of stress testing in asymptomatic patients.

As pointed out in the Widowmaker, there is no data which suggest that stress testing improves outcomes for cardiac patients.

Stress tests by design tell us nothing about the noncritical build up of atherosclerotic plaque. You can have a normal stress test and have a huge burden of plaque in your arteries.

It is this silent build up of atherosclerosis, with sudden rupture of plaque, which results in sudden death in most cardiac patients.

What Is The Breast Cancer Equivalent Of CAC?

A CAC of the breast would identify abnormal cells as soon as they began on the presumably multi-year road to becoming a full flown cancer.

To be fully equivalent to the CAC, the breast CAC would have to have a proven treatment that could be instituted once a certain stage of cell transformation had been reached.

For atherosclerosis, that treatment is statin drugs, which are recommended for those with high risk CAC scores.

For breast cancer, the treatment of choice is mastectomy.

 Would Widespread Institution of CAC Screening Save Millions of Lives?

For mammograms based on a review of all the evidence, the US PTF concluded:

Over a 10-year period, screening 10,000 women ages 50 to 59 years will result in 8 (95% confidence interval [CI], 2 to 17) fewer breast cancer deaths, and screening 10,000 women ages 60 to 69 years will result in 21 (95% CI, 11 to 32) fewer deaths.

To scientifically determine how many lives are saved by CAC screening, we would need an extremely large randomized controlled trial lasting for at least 6 years.

Individuals with low or intermediate risk from standard risk factors for atherosclerosis would receive a standard approach to management or would undergo CAC screening with treatment determined by calcium score.

Such trials have been proposed but to date have not been funded by the NIH thus we may not have a definite answer for a long time.

Should CAC Scans Be Covered Like Mammography?

I am very conflicted on this question.

On one hand I do believe that appropriate use of CAC scans prevents heart attacks and sudden death. How many, remains to be seen. As we saw for mammography, only large scale randomized trials will tell us for sure who will benefit and how much.

On the other hand, I can see potential for abuse, and in the wrong hands, excessive downstream invasive testing, which will minimize the benefits of early detection.

If CAC scans are covered by insurance and used widely, they could become a method for unscrupulous cardiology centers and doctors to proceed to unnecessary testing that would ultimately increase the amount of inappropriate coronary stenting.

Indeed, it is quite ironic that the major theme of The Widowmaker, that of the medical-industrial stent complex suppressing CAC scan usage, is quite illogical, for widespread, injudicious use of CAC scanning would be a boon for stent inserters and makers.

The inappropriate use of CAC scan information is limited currently because most of the doctors ordering them are primarily interested in prevention, not in generating more testing and procedures.

The other limit on its use is cost. For 99% of my patients the $125 for a CAC scan at my hospital is not a limiting factor.

On the other hand, in a less affluent population, this would be a large and limiting expense; the poor would be getting a lesser standard of care.

The cases of patients in The Widowmaker who feel like a CAC scan saved their lives are very similar to those of breast cancer patients who feel mammography saved theirs.

These patients often become passionate advocates for a specific test based on their own experience. The Widowmaker, in fact, was funded by David Bobbett, an Irish millionaire who discovered that he had an extremely high calcium score and now feels like everyone should get the test.

Bobbett is convinced that the test saved his life, but all anecdotal patient stories about CAC scans “saving their life” have to be taken with a grain of salt.

After this (far too long) discussion I have to conclude that although they share many features, CAC scans are not the mammography of the heart.

uncharacteristically verbosely yours,

-ACP