Category Archives: Coronary Artery Calcium Scan

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

Should All Patients With A High Coronary Calcium Score Undergo Stress Testing?

Coronary artery calcium (CAC) scans are an excellent tool for better defining coronary heart disease risk in many individuals. In light of the recent ACC/AHA guidelines endorsement of CAC, the skeptical cardiologist anticipates that primary care physicians will be ordering more and will often be faced with the question of what to do with abnormally high results.

There are two, diametrically opposed viewpoints which have been taken on this issue.

The Argument For Stress Testing

The majority of cardiologists are likely to fall into the camp of “more testing is good” which was summarized in a  State of The Art article that Dr. Harvey Hecht wrote in JACC recently.

The argument appears logical and is as follows:

  1. There is a high yield of abnormal results from stress testing when done on patients with high CAC.

The appropriateness of stress testing after CAC scanning in asymptomatic patients is directly related to the CAC score. The incidence of abnormal nuclear stress testing is 1.3%, 11.3%, and 35.2% for CAC scores 400, respectively .

2. The higher yield for ischemia/abnormal tests in patients with >400 CAC implies the ability to further risk stratify patients thus leading to guideline recommendations:

It is only in the >400 group that the pretest likelihood is sufficiently high to warrant further evaluation with myocardial perfusion imaging, for which there is a IIb recommendation

Hecht references a 2010 guideline issued by ACC/AHA (2010 ACCF/AHA Guideline for Assessment of Cardiovascular Risk in Asymptomatic Adults) which states

1. Stress myocardial perfusion imaging (MPI) may be considered for advanced cardiovascular risk assessment in asymptomatic adults with diabetes or asymptomatic adults with a strong family history of CHD or when previous risk assessment testing suggests a high risk of CHD, such as a coronary artery calcium (CAC) score of 400 or greater. (Level of Evidence: C)

Stress MPI testing is more sensitive than stress ECG testing alone but in clinical practice I see a very high rate of false positive stress MPI results. Stress MPI is also much more expensive than stress ECG testing and delivers significant radiation exposure to patients.

Thus if stress MPI is performed on all individuals with CAC>400 we are likely to generate lots of abnormal tests followed by lots of unnecessary down-stream testing.

Further support for the stress test approach comes from a 2013 report on appropriate use issued by an alphabet soup of cardiovascular professional organizations

Below is the incredibly complicated chart summarizing what tests can follow another abnormal test. Interestingly, in this chart the report consider it appropriate (A) to perform stress tests on individuals with calcium scores >100

Stress Testing-Costs and Downsides

The cynic in me has to point out that the average CAC score  for white males of 67 years is 98 and that of 68 years is 115. Thus, this algorithm has the potential to recommend stress testing be performed on half of all white males with no symptoms over the age of 67.

The costs of this approach would be astronomical.

This guideline supports stress ECG, stress MPI and stress echo as appropriate.  Stress MPI is considerably more expensive than stress ECG and carries substantial radiation burden. Stress echo in my experience,  if performed and read properly has the lowest incidence of false positives and is more appropriate therefore for screening asymptomatic individuals.

All this stress testing stands to benefit the various members of the alphabet soup above, especially those who read nuclear stress tests or stress echo or who do catheterizations with stents. (Full disclosure I am board certified in nuclear cardiology and echocardiography and read both stress MPI and stress echos. I don’t do catheterizations.)

It’s also important to point out that these appropriate usage criteria, with rare exceptions are based primarily on the expert opinion of the stakeholders who stand to benefit from the additional testing.

The unspoken third leg of the argument for stress testing is that once an abnormal stress test is found and the patient is noted to be in a higher risk category for events, therapy will be changed and this therapeutic intervention will improve outcomes.

This therapeutic intervention could be more intense management of risk factors for CAD but in most cardiologist’s and patient’s minds the next step is coronary angiography with the potential to stent blocked coronaries or to perform coronary bypass surgery.

Diabetic Patients With High CAC

Asymptomatic individuals with diabetes are recognized as intrinsically higher risk for cardiac events and commonly do not experience symptoms even with advanced CAD.

Thus, they are often the focus of more intense screening recommendations.

In 2017, The Imaging Council of the American College of Cardiology published their review of evidence regarding the use of noninvasive testing to stratify asymptomatic patients with diabetes with regard to to coronary heart disease, ultimately coming up with the algorithm below.

Their arguments were similar to Hecht’s for the general population:

Asymptomatic patients with diabetes who have high CAC scores have a high prevalence of inducible ischemia on stress imaging. In a prospective study, 48% of patients with diabetes with a CAC score of 400 had silent ischemia on SPECT imaging, and in those with a score of 1000, 71.4% had inducible ischemia . The majority of the defects were moderate to severe. Patients with diabetes with inducible ischemia have a higher annual death

Despite higher rates of ischemic stress test results in diabetics they did not recommend stress testing for all:

the data in DM suggest that routine screening with MPI of all asymptomatic patients is likely to have a low yield and have a limited effect on patient outcome. The yield of MPI can be improved by selecting a higher-risk group of patients with symptoms, peripheral vascular disease, CKD, an abnormal ECG, or a high CAC score (e.g., >400) (83,84). In such patients, intense medical therapy appears to retard progression of asymptomatic and symptomatic CAD (72).

Importantly, they noted the absence of evidence for revascularization in this population:

Whether coronary revascularization offers additive prognostic benefit to medical therapy when the ischemic burden exceeds any particular threshold is still unclear for the asymptomatic diabetic population.

The Argument Against Stress Testing

The argument for stress testing for high CAC rests on the assumption that identifying those individuals with significant ischemia due to tightly blocked coronary arteries can improve outcomes. This hypothesis has never been tested, let alone proven.

It may seem logical that those asymptomatic individuals with high risk CAC scores >400 and ischemia would benefit from an invasive strategy with coronary angiography followed by either stenting or bypass surgery but it is entirely possible that such an invasive strategy could cause more harm than good.

Harm comes from subjecting those individuals with abnormal stress tests to a potentially lethal procedure-cardiac catheterization.

David Schade, an endocrinologist, has opined persuasively on the inadvisability of either stress testing or cardiology referral in those with high CACS.

He correctly points out the limitations of coronary angiography which some cardiologists are very eager to perform

In many locations, stress testing is performed after referring the asymptomatic patient to a cardiologist. After a positive stress test, the next step is usually coronary angiography to identify obstructive lesions. A recent review of coronary angiography recommends caution in the use of this test because (1) the resolution of coronary angiography is low; (2) the obtained images are two dimensional, making it difficult to define the shape of the vessel; and (3) the assessment of obstruction does not include the presence of previously developed collateral vessels, which may provide adequate blood flow past the obstruction 

He quotes the USPSTF on the possible harm of this approach:

And he correctly points out that since the 2007 publication of the COURAGE trial we have known that catheterization followed by stenting does not improve outcomes in patients with stable CAD

Accord to the US Preventive Services Task Force: “The primary tangible harm of screening exercise tolerance testing is the potential for medical complications related to cardiac catheterization done to further evaluate a positive result. Coronary angiography is generally considered a safe procedure. Of all persons undergoing outpatient coronary angiography, however, an estimated 0.08% will die as a result of the procedure and 1.8% will experience a complication. Complications of coronary angiography include myocardial infarction, stroke, arrhythmia, dissection of the aorta and coronary artery, retroperitoneal bleeding, femoral artery aneurysm, renal dysfunction, and systemic infection”

In many locations, stress testing is performed after referring the asymptomatic patient to a cardiologist. After a positive stress test, the next step is usually coronary angiography to identify obstructive lesions. A recent review of coronary angiography recommends caution in the use of this test because (1) the resolution of coronary angiography is low; (2) the obtained images are two dimensional, making it difficult to define the shape of the vessel; and (3) the assessment of obstruction does not include the presence of previously developed collateral vessels, which may provide adequate blood flow past the obstruction 

Schade’s algorithm for management of a high CAC specifically recommends against referral to a cardiologist or performance of a stress test.

It emphasizes very intense management of risk factors with lifestyle changes and medical therapy with LDL goal <70.

As a cardiologist with a strong interest in prevention of atherosclerosis I agree with many of Schade’s points. I do, however, believe that high risk patients can benefit from seeing a cardiologist who is very focused on prevention of atherosclotic complications rather than performing procedures.

I don’t routinely recommend stress testing for my patients with high CAC but I have a low threshold for recommending stress testing in them based on worrisome symptoms, especially in those who are more sedentary or are diabetic.

A randomized trial comparing the outcomes of stress testing versus aggressive optimal medical therapy for the asymptomatic individual with high CAC is sorely needed. Until then, I remain

Skeptically Yours,

-ACP

 

The MESA App-Estimating Your Risk of Cardiovascular Disease With And Without Coronary Calcium Score

Yesterday, I laid out the case for utilizing coronary artery calcium score (CACS) to further refine the assessment of youngish patients risk of developing cardiovascular disease (ASCVD). I referenced the ACC/AHA ASCVD risk estimator tool (app available here) as the starting point but if I have information on my patient’s CACS I use a new and improved tool called the MESA risk score calculator.

It is available online and through an app for Apple and Android (search in the app store on “MESA Risk Score” for the (free) download.)

The MESA tool allows you to easily calculate how the CACS effects you or your patient’s 10 year risk of ASCVD.

The Multi-Ethnic Study of Atherosclerosis (MESA) is a study of the characteristics of subclinical cardiovascular disease (disease detected non-invasively before it has produced clinical signs and symptoms) and the risk factors that predict progression to clinically overt cardiovascular disease or progression of the subclinical disease. MESA researchers study a diverse, population-based sample of 6,814 asymptomatic men and women aged 45-84. Approximately 38 percent of the recruited participants are white, 28 percent African-American, 22 percent Hispanic, and 12 percent Asian, predominantly of Chinese descent.

To use the score you will need information on the following risk factors:

age, gender, race/ethnicity, diabetes (yes/no), current smoker (yes/no), total and HDL cholesterol, use of lipid lowering medication (yes/no), systolic blood pressure (mmHg), use of anti-hypertensive medication (yes/no), any family history of heart attack in first degree relative (parent/sibling/child) (yes/no), and a coronary artery calcium score (Agatston units).

In many cases the CACS dramatically lowers or increases the risk estimate.

In this example a 64 year old man with no discernible risk factors has a CACS of 175
The 10 year risk of a CHD event almost doubles from 4.7% to 7.6% when the CACS is added to the standard risk factors and moves into a range where we need much more aggressive risk factor modification.

On the other hand if we enter in zero for this same patient the risk drops to a very low 1.9%.

It’s also instructive to adjust different variables. For example, if we change the family history of heart attack (parents, siblings, or children) from no to yes, this same patient’s risk jumps to 7.2% (2.6% with zero calcium score and to 10.4% with CACS 175.)

It can also be used to help modify risk-enhancing behaviors. For example if you click smoker instead of non-smoker the risk goes from 4.7% to 7.5%. Thus, you can tell your smoking patient that his risk is halved if he stops.

Discussions on the value of tighter BP control can also be informed by the calculator. For example, if  our 64 year old’s systolic blood pressure was 160 his risk has increased to 6.8%.

How Does Your CACS Compare To Your Peers?

A separate calculator let’s you see exactly where your score stands in comparison individuals with your same age, gender, and ethnicity

The Coronary Artery Calcium (CAC) Score Reference Values web tool will provide the estimated probability of non-zero calcium, and the 25th, 50th, 75th, and 90th percentiles of the calcium score distribution for a particular age, gender and race. Additionally, if an observed calcium score is entered the program will provide the estimated percentile for this particular score. These reference values are based on participants in the MESA study who were free of clinical cardiovascular disease and treated diabetes at baseline. These participants were between 45-84 years of age, and identified themselves as White, African-American, Hispanic, or Chinese. The current tool is thus applicable only for these four race/ethnicity categories and within this age range.

The calculator tells us that 75% of 64 year old white males have a zero CACS and that the average CACS is 61.

Unlike SAT scores or Echo Board scores you don’t want your CACS percentile status to be high. Scores >75th percentile typically move you to a higher risk category, whereas scores <25th percentile move you to a lower risk category, often with significant therapeutic implications.

Scores between the 25th and 75th percentile typically don’t significantly change the risk calculation.

Exploring Gender Differences In CACS

If we change the gender from male to female on our 64 year old the risk drops considerably from 4.7% down to 3.3%. This graph demonstrates that over 20% of women between the ages of 75 and 84 years will have zero calcium scores.

The graph for men in that same range shows that only around 10% will have a zero CACS.

I’ve been asked what the upper limit is for CACS but I don’t think there is one. I’ve seen numerous patients with scores in the high two thousands and these graphs show individuals in the lowest age decile having scores over 2981.

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.

Antiatherosclerotically Yours,

-ACP