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..
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.
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.
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.
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)
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.
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.
I 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.
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.
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.
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
-18.104.22.168. 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 (S22.214.171.124-1–S126.96.36.199-8). 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 (S188.8.131.52-9–S184.108.40.206-12). 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 (S220.127.116.11-13). With increasing age, 10- year risk accompanying CAC scores of 1 to 99 rises, usually crossing the 7.5% threshold in later middle age (S18.104.22.168-13). When the CAC score is zero, some investigators favor remeasurement of CAC after 5 to 10 years (S22.214.171.124-14–S126.96.36.199-16). 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 (S188.8.131.52-17). A prospective randomized study of CAC scoring showed improved risk factor modification without an increase in downstream medical testing or cost (S184.108.40.206-18). 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 (S220.127.116.11- 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
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?
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.
Based 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.
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.
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.
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.