Category Archives: Cardiac Tests

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

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

One Question On A Borderline Stress Test and One Comment About Me , Gundry And BIG PHARMA

A reader asks me the following question:

I’m 35 years old male and was positive for myocardial ischemia during stress test. The cardiologist said that my result was borderline. I’m not sure what does he meant by “borderline”. Also does it help if I do CAC score since my stress test already came out with positive MI?

Good questions.

First off, to understand what any stress test means we have to know the pre-test probability of disease. For example, in 35 year old males without chest pain the likelihood of any significantly blocked coronary artery is very low. This means that the vast majority of positive or borderline tests in this group are false positives, meaning the test is abnormal but there is no disease.

Even if we add exertional chest pain into the mix the probability of a tightly blocked coronary in a 35 year year old is incredibly low (but there are some congenital coronary anomalies that occur.)

The accuracy of stress tests varies depending on the type. The standard treadmill stress test with ECG monitoring is about 70% sensitive  and 70% specific. Adding on a nuclear imaging component improves the sensitivity (it makes it more likely we will pick up a blockage if it is present) to about 85% however, in the real world, the specificity (chance of a false positive) is still quite high. Accuracy varies a lot depending on how good the study is and how good the reader is.

Borderline for either the stress ECG the stress nuclear (or stress echo) means that the test wasn’t clearly abnormal but it wasn’t clearly normal. It is in a grey zone of uncertainty.

Given your low pre-test probability of disease it is highly likely your “borderline” test result is a false positive. Whether anything else needs to be done at this point depends on many factors (some from the stress test)  but most importantly, the nature of the symptoms that prompted the investigation in the first place.

If there are no symptoms and  you went for more than 9 minutes on the treadmill likely nothing needs to be done.

Would a coronary calcium scan add anything?

A very high score (>let’s say 100 for age 35) would raise substantial concerns that you have a coronary blockage.

A zero score would be expected in your age group and probably wouldn’t change recommendations .

A score of 1 up to let’s say 100  means you have a built up a lot more plaque than normal and should look at aggressive modification of risk factors but likely wouldn’t change other recommendations.

So the CAC might be helpful but most likely it would be a zero and not helpful.

A Nasty Comment.

The skeptical cardiologist gets lots of nasty comments about his post on the bad science behind Dr. Esselstyn’s diet and another post on the totally bogus Plant Paradox book/diet by Stephen Gundry. I don’t think Esselstyn is a quack but he pretends that there is scientific support for his wacky diet when all he has is anecdotes.

With Gundry, on the other hand, there is a strong smell of quackery.

With this new book he’s developed a line of ridiculous foods that he’s approved.

Gundry will sell you a 75$  piece of chocolate with resveratrol added to it. Despite the multiple health claims for this antioxidant (found in red wine) there are no proven health benefits.

 

Snake oil and supplements abound in all of his presentations and there is much promotion of useless expensive skincare products and  foods that only he sells.

I’m thinking of  adding promotion of special, super-charged olive oil to the red flags of quackery.

There’s no health  reason to get extra-virgin olive oil adulterated with anything. Just make sure you are actually getting EVOO.


Here’s one of Gundry’s supporters comments.

Thank you for your opinion and that’s exactly what it is YOUR OPINION. I suggest you try the Plant Paradox. You sound like someone from a pharmaceutical company. Why don’t you write about how BIG PHARMA is deceiving the public along with how they are keeping people sick.

People who leave nasty comments on my blog typically don’t identify themselves. I can’t tell if this is an authentic comment or someone paid by Gundry’s vast snake oil empire.

They really like using ALL CAPs.

And they like to accuse me of being from BIG PHARMA or in the pay of BIG PHARMA.

BIG PHARMA and I, apparently, have the goal of misleading the populace about the benefits of Gundry’s BS diet and useless supplements so that they will remain sick and require drugs that  gain us huge profits.

I’m still waiting for the checks from BIG PHARMA to roll in. In the meantime I am scrupulously avoiding lunch with pharmaceutical reps and drug/device sponsored boondoggles.

Pharmalargically Yours,

-ACP

N.B. If you’d like to see how much money BIG PHARMA is paying me (or any doctor) you can go to the Dollars for Docs website run by Pro Publica here.

“Should You Get A Routine Annual Electrocardiogram?”, Revisited

Four years ago the skeptical cardiologist wrote a post which outlined the reasons why most people should avoid getting a routine annual electrocardiogram.

I pointed out that

If you …feel fine (meaning without symptoms or asymptomatic), exercise regularly, have never had heart problems,  and have a pulse between 60 and 90, the value of the routine annual ECG is very questionable. In fact, the United States Preventive Services Task Force (USPFTF)

“recommends against screening with resting or exercise electrocardiography (ECG) for the prediction of coronary heart disease (CHD) events in asymptomatic adults at low risk for CHD events”

(for asymptomatic adults at intermediate or high risk for CHD they deem the evidence insufficient). The USPSTF feels that that the evidence only supports an annual BP screen along with measurement of weight and a PAP smear.

Yesterday, the USPSTF published an updated analysis which confirmed this recommendation:

The U.S. Preventive Services Task Force (USPSTF) recommends against preventative screening with resting or exercise electrocardiography (ECG) in asymptomatic adults at low risk of cardiovascular disease events in an updated recommendation statement published June 12 in the Journal of the American Medical Association (JAMA).

I should point out that I still believe (although some would disagree) screening for atrial fibrillation with methods other than a 12-lead ECG (including taking the pulse or checking a single lead ECG with a Kardia device) is worthwhile.

Below, I’ve reposted relevant sections of my 2014 post which emphasizes the problem of false positives and false negatives which are quite frequent with any screening test but are particularly worrisome with the routine 12-lead ECG.

 


To many, this seems counter-intuitive: how can a totally benign test that has the potential to detect early heart disease or abnormal rhythms not be beneficial?

There is a growing movement calling for restraint and careful analysis of the value of all testing that is done in medicine. Screening tests, in particular are coming under scrutiny.
Even the annual mammogram, considered by most to be an essential tool in the fight against breast cancer, is now being questioned.

My former cardiology partner, Dr. John Mandrola, who writes the excellent blog at http://www.drjohnm.org, has started an excellent discussion of a recent paper that shows no reduction of mortality with the annual mammogram. He looks at the topic in the context of patient/doctor perception that “doing something” is always better than doing nothing, and the problem of “over-testing.”

In my field of cardiology there is much testing done. It ranges from the (seemingly) benign and (relatively) inexpensive electrocardiogram to the invasive and potentially deadly cardiac catheterization. For the most part, if patients don’t have to pay too much, they won’t question the indication for the tests we cardiologists order. After all, they want to do as much as possible to prevent themselves  from dropping dead from a heart attack and they reason that the more testing that is done, the better, in that regard.

The Problem of False Positives and False Negatives

But all testing has the potential for adverse consequences because of the problem of false positives and negatives. To give just one example: ECGs in people with totally normal hearts are regularly interpreted as showing a prior heart attack. This is a false positive. The test is positive (abnormal) but the person does not have the disease.

12 lead ECG routinely performed prior to surgery and interpreted by computer as ASMI or anteroseptal myocardial infarction ( heart attack).Patient with totally normal heart. Often such false positives are due to poor placement of the ECG leads

False positives lead to unnecessary worry, anxiety, and testing. More testing is highly likely to be ordered; specifically, a stress test. Stress tests in low risk, asymptomatic individuals often result in false positive results. After a false positive stress test, it is highly likely that a catheterization will be ordered. This test carries potential risks of kidney failure, heart attack, stroke and death. It is bad enough that the cascade of testing initiated by an abnormal, false positive,  screening test results in unnecessary radiation, expense and bother but  in some cases it end up killing patients rather than saving lives.

On the other end of the spectrum is the false negative ECG. Most of my patients believe that if their ECG is normal then their heart is OK. Unfortunately the ECG is very insensitive to cardiac problems that are not related to the rhythm of the heart or an acute heart attack.

Patients who have 90% blockage of all 3 of their major coronary arteries and are at high risk for heart attack often have a totally normal ECG. This is a false negative. The patient has the disease (coronary artery disease), but the test is normal. In this situation the patient may be falsely reassured that everything is fine with their heart. The next day when they start experiencing chest pain from an acute heart attack, they may dismiss it as heart burn instead of going to the ER.

More and more, screening tests like the ECG and the mammogram  are rightfully being questioned by patients and payers. For a more extensive discussion about which tests in medicine are appropriate check out the American Board of Internal Medicine’s http://www.choosingwisely.org.

Keep in mind: not uncommonly,  doing more testing can result in worse outcomes than doing less.

Skeptically Yours,

-ACP

h/t Jerry , the life coach of the skeptical cardiologist , who originally posed this question to me.

 

The Skeptical Cardiologist Answers Good Questions: Retesting For Symptomatic Benign PVCs?

One of the many things I enjoy about writing this blog is the interesting comments and questions that readers post. Many of them stimulate me to better answer and inform my patients.

Here’s one such question (about premature ventricular contractions):

Wondering your opinion on retesting. I’ve had PVCs since I was 15 (63 now) and they have come and gone over the years, attributed to hormones, low potassium, stress, and dehydration/bad diet. Recently they started again and are driving me insane and none of the usual fixes are working. Two ER visits with normal EKGs and my cardiologist all say no worries. I’m thinking maybe I should have another ultrasound, buy MD doesn’t think it’s necessary. I had a perfectly normal cath in 2015 but no tests since. Your thoughts? Thank you.

This was the response I typed off the top of my head:

Good question. I consider retesting for patients who have not had documentation of “structurally normal heart” for some time and who have a significant change in their symptoms. You would qualify since no testing in 3 years and worsened symptoms.
Typically I would order a stress echocardiogram which allows a reassessment of both LV structure and function and for any blockage in the coronary arteries and I would consider some kind of monitor-a 24 hour Holter would be fine if you are having daily symptoms.
You might also consider acquiring an AliveCor device to monitor your rhythm with symptoms. I’ve written a lot about this elsewhere on this site. Unfortunately AliveCor does not identify PVCs but if you connect via KardiaPro with your physician your recordings can be viewed and interpreted by him/her.

The answer reflects my clinical practice, which is based on 30 years of experience taking care of patients with PVCs, in conjunction with regularly reading papers, reviews and guidelines in this area.

Periodically, both for specific patient problems and for blog questions, I will search the medical/scientific literature and review guideline publications to see if there is any new information that I am unaware of to ensure that my recommendations are scientifically grounded.

In this case, a more prolonged search of the literature did not yield precise guidance on the frequency of retesting of patients with benign PVCs.

This 2014 guideline comments briefly on the evaluation and treatment of PVCs without structural heart disease (SHD):

In the absence of SHD, the most common indication for treating PVCs remains the presence of symptoms that are not improved by explanation of their benign nature and reassurance from the physician.

In addition, some patients may require treatment for frequent asymptomatic PVCs if longitudinal imaging surveillance reveals an interval decline in LV systolic function or an increase in chamber volume.

For patients with  >10,000 PVCs/24 h, follow-up with repeat echocardiography and Holter monitoring should be considered.

In patients with fewer PVCs, further investigation is only necessary should symptoms increase.

It should also be recognized that PVC burden often fluctuates over time.

This initial testing approach corresponds closely to what I wrote in my post on benign PVCs here.

Retesting with echocardiography and Holter monitoring is advised for those few patients who have lots of PVCs, but the frequency of this retesting is not specified and cardiologists have to use their best judgement, balancing the cost (to patient and to society) and patient safety.  Most cardiologists will err on the side of more frequent repeat testing for a variety of reasons.

Personally, I will advise an annual echocardiogram to such patients since they are at a higher risk of developing a cardiomyopathy.

In the absence of really frequent PVCs (>10,000 per 24 hours is a nice round number, but the precise cut-off is debatable), we should probably only repeat testing if the patient recognizes a significant change in their symptoms.

The reader clearly fits into that category, and retesting in her will provide reassurance that all is still good with her heart. This, in turn, should help with managing symptoms and preventing recurrent ER visits.

The final question (and the toughest) that we could pose related to retesting is “What is the time interval that one should wait before retesting in a patient with worsened symptoms?”

For example, if the reader had a normal echocardiogram 6 months ago should we repeat it when symptoms worsen? My reflex answer would be no, but at some time interval depending on the individual characteristics of the case-patient risks for heart disease, patient anxiety levels, patient symptom severity and frequency, the answer would become yes.

Cardiologists have to answer dozens of questions like this daily.  There is no science to inform a precise answer, consequently the answers will vary wildly from one cardiologist to another depending on a variety of factors specific to the cardiologist.

Those cardiologist-specific factors are complex and sometimes controversial. Part of this makes up the art of medicine and part reflects the business of medicine. They are definitely worthy of another post when time permits.

Questioningly Yours,

-ACP

N.B. The Eternal Fiancee’ (my layperson surrogate) expressed surprise that one could have 10 000 PVCs per day. I told her that if your heart beats roughly once per second (6o beats per minute) since there are  60 x 60 x 24 = 86400 seconds in a day, your heart beats almost 90 000 times in 24 hours.

Thus, roughly  1 in 9 beats is a PVC.

AliveCor Mobile ECG : Ways To Minimize Low Voltage and Unclassified Recordings

Sometimes AliveCor’s Mobile ECG device yields unclassified interpretations of recordings. Understandably if you want to know whether your rhythm is normal or atrial fibrillation, the unclassified  classification can be very frustrating.

There are various caues of an unclassified tracing with different solutions.  Some unclassified recordings are due to a heart rate over 100 BPM or under 50 BPM and cannot be fixed. Similarly, some patients with ectopic beats like PVCS may consistently generate unclassified interpretations (see my discussion here).

Artifacts induced by poor recording techniques are common as a cause and almost always can be fixed.

These can be reduced by minimizing motion, extraneous noise, and maximizing contact with the electrodes.  Follow all the steps AliveCor lists here.

For me, the following step is crucial

  • If your fingers are dry, try moistening them with antibacterial wipes or a bit of lotion

And be aware the device needs to be near the microphone of your iPad or smartphone.

Low Voltage As Cause of Unclassified Kardia Recordings

Another cause of unclassified interpretations is a low voltage recording (which I initially discussed here.).

At the recent ACC meeting I asked Alivecor inventor and CEO David  Albert if he had any solutions to offer for those who obtain unclassified low voltage AliveCor tracings.

He told me that the cause is often a vertically oriented heart and that recording using the lead II technique can often solve the problem.

Lead II involves putting one electrode on your left knee and one your right fingers as described in this video:

Reader “J”  recently sent me a series of Kardia ECG recordings,  some of which were unclassified , some normal and one read as possible atrial fibrillation.

The unclassified and possible AF tracings looked like this:

 

They were very regular with a rate between 80 and 100 BPM but they totally lacked p waves. It was not clear to me what the rhythm was on these tracings.

Other tracings had lowish voltage but the p waves were  clearly visible  and Kardia easily classified them as normal

Lowish voltage with p waves (Type B)

 

Good QRS voltage with clear p waves ( Type B

 

Still others had improved QRS voltage with clear p waves and were also classified  appropriately as normal

 

After some back and forth emails we discovered that the ECG recordings with no p waves were always  made using the chest lead recording.   AliveCor-describes this as follows:

  • For an Anterior Precordial Lead, the device can be placed on the lower left side of the chest, just below the pectoral muscle. The bottom of the smartphone or tablet should be pointing towards the center of the body.

Mystery solved!

There is an abnormal cardiac rhythm that is regular between 80 and 100 BPM with no p waves and normal QRS called junctional tachycardia but in J’s case the absent p waves are related to the recording site.

Also, note that for this young woman the lead II voltage (Type B tracing) is much higher than the standard, lead I voltage (type A tracing).

Lead II With Pants On

After Dr. Albert told me of the advantages of Lead II I responded that it seemed somewhat awkward to take one’s pants off in order to make an ECG recording.

He immediately reached in his suit pocket and pulled out a pen-shaped device and began spraying a liquid on his left knee.

To my surprise he was able to make a perfect Lead II recording without taking his pants off!

Lessons learned from reader J and Dr. A:

  • Consider trying different leads if the standard Lead I (left hand, right hand) is consistently yielding unclassified ECG recordings
  • Try Lead II (left knee, right hand) to improve voltage and recording quality
  • You can record off your knee even with your pants on if you are prepared to spray liquids on your pants

Pantsonically Yours,

-ACP

What Should Your Maximal Exercise Heart Rate Be?: The Importance Of Using The Right Age-Predicted HRmax Formula

A reader who runs 5Ks posted a question recently which indicated concern that his heart rate during intense exercise was much higher than his age-predicted heart rate.  He writes

I’m 65, exhaustion HRmax is 188, HRave for 5k is usually 152-154 and interval HRmax is usually 175-179 depending on how hard I push”

He wondered if he should be concerned about being a “high-beater.”

This prompted the skeptical cardiologist to examine the literature on age-predicted maximal heart rate which led to the shocking discovery that the wrong formula is being utilized by most exercise trainers and hospitals.

First , some background.

The peak heart rate achieved with maximal exertion or HRmax has long been known to decline with aging for reasons that are unclear.

The HR achieved with exercise divided by the HRmax x 100 (percentage HRmax) is widely used in clinical medicine and physiology as a basis for prescribing exercise intensity in cardiac rehab programs, disease prevention programs and fitness clinics.

During stress tests we seek to have patients exercise at least until  their heart rate gets to at 85% of HRmax.

The Traditional Formula For HRmax

The formula that is widely used for HRmax is

HRmax = 220-age

It appears to have originated from flawed studies in the early 1970s. These studies included subjects with cardiovascular disease, smokers and patients on cardiac medications.

The Improved HRmax Formula

Tanaka, et al in 2001 performed a meta-analysis of previous data on HRmax along with accumulating data in their own lab. This was the first study to examine healthy, unmedicated, nonsmokers. In addition each subject achieved a verified maximal level of effort as documented by metabolic stress testing.

Their analysis obtained the regression equation (which I term the Tanaka equation)

HRmax = 208-(0.7 x age) 

Below is the graph of the laboratory measurements from which the regression equation was obtained.

Relation between maximal heart rate (HRmax) and age obtained from the prospective, laboratory-based study.(Tanaka, et al)

This graph shows how  inaccurate the traditional equation is, especially in older  individuals like my reader:

Regression lines depicting the relation between maximal heart rate (HRmax) and age obtained from the results derived from our equation (208 − 0.7 × age) (solid linewith 95% confidence interval), as compared with the results derived from the traditional 220 − age equation (dashed line). Maximal heart rates predicted by traditional and current equations, as well as the differences between the two equations, are shown in the table format at the top.(from Tanaka, et al)

The traditional equation in comparison to the Tanaka equation  overestimates HRmaxin young adults, intersects with the present equation at age 40 years and then increasingly underestimates HRmaxwith further increases in age. For example, at age 70 years, the difference between the two equations is ∼10 beats/min. Considering the wide range of individual subject values around the regression line for HRmax(SD ∼10 beats/min), the underestimation of HRmaxcould be >20 beats/min for some older adults.

There are likely lots of perfectly healthy individuals in their sixties and seventies then who have heart rates at maximal exertion that exceed by 10 to 20 beats per minute the HR max predicted by the traditional formula.

This is due to a combination of the inaccuracy of the traditional formula and the wide variation in normal HR max at any given age (standard deviation (SD) of approximately 10 beats/min.)

Thus, my reader at age 65 would have a HRmax predicted by the Tanaka equation as

208-0.7 x 65=162

If we allow for a 10 BPM range of normality above and below 162 BPM we reach 172 BPM which gets close to  but doesn’t reach the reader’s 188 BPM.

If you examine the scatterplot of the Tanaka data you can see that several of the points for age 65 reach into the 180s so chances are my reader is still within normal limits

The Bottom Line on HRmax

The widely used traditional formula for predicting HR max is inaccurate.

Athletes, trainers, physicians and hospitals should switch to using the superior Tanaka HR max formula.

Individuals should keep in mind that there is a wide range of HR response to exercise in normals and variations of 10 BPM above and below the predicted response are common and of no concern.

Chronotropically Yours

-ACP

Addendum. The 220-age formula is so heavily etched into my brain that I used 220 instead of 208 when I initially calculated the predicted max HR for my reader. this has been corrected.Thanks to Chris Sivewright for pointing this out.

Can AliveCor’s Mobile ECG Device Combined With Its Kardia Pro Cloud-Based Platform Replace Standard Long Term Rhythm Monitors?

In March of 2017 AliveCor introduced Kardia Pro, a cloud-based software platform that allows physicians to monitor patients who use the Kardia mobile ECG device.

I have been utilizing the Kardia mobile ECG  device since 2013 with many of my atrial fibrillation (AF)  patients and have  found it be very useful as a personal intermittent long term cardiac monitor. (see here and here)

I signed up for the Kardia Pro service about 3 months ago and all of my patients who purchased Kardia devices prior to March of 2017 have been migrated automatically to Kardia Pro by AliveCor.

Now (post March 2017),  patients who acquire a Kardia device must sign up for the Kardia Pro service at $15 per month to connect with a  physician.

I think this is money well spent and I’ll demonstrate how the service works with a few examples.

Monitoring Patients With Atrial Fibrillation

 I saw a 68 year old man with persistent atrial fibrillation that was first diagnosed at the time of pneumonia in late 2017.

He underwent a cardioversion after recovering from the pneumonia but quickly reverted back to AF. His prior cardiologist offered him the option of repeat cardioversion and long term flecainide therapy for maintenance of normal sinus rhythm (NSR) but he declined.

When I saw him for the first time in the office  a  month ago I  listened to his heart and to my surprise, noted a regular rhythm: an AliveCor recording in the office confirmed he was in NSR. The patient had been unaware of when he was in or out of rhythm

We discussed methods for monitoring his rhythm at this point which include a 24 Holter monitor, a 7 to 14 day Long Term Monitor, a Cardiac Event Monitor and a Mobile Cardiac Outpatient Telemetry device. These devices are helpful and although expensive are often covered by insurance.  They require wearing electrodes or a patch continuously and the results are not immediately available.

I also offered him the option of monitoring his AF using a Kardia device with the recordings connected to me by Kardia Pro.

He purchased the device on his own for $99, downloaded the app for his smartphone and began making recordings.

I enrolled him in my Kardia Pro account and he received an email invitation with a code that he entered which connected his account with mine, allowing me to view all of his recordings as they were made.

When I log into my Kardia Pro account I can now view a graphic display of the recordings he has made with color coding of whether they were considered normal or abnormal by Kardia.

The patient overview page also displays BP information if the patient is utilizing certain Omron devices which work with Kardia.

kardia pro wc monthly

The display shows that after our office visit he maintained NSR for 3 days (green dots) and then intermittently had ECG recordings classified as AF (yellow dots) or unclassified (black).

The more he used the device and got feedback on when he was in or out of rhythm the more he was able to recognize symptoms that were caused by AF.

I can click on any of the dots and six second strips of the full recording are displayed.  In the example below I clicked on 2/27 which has both an unclassified recording (which is atrial flutter) and an AF recording

Clicking on the ECG strips brings up  the full 30 second recording on a page that also allows me to assign my formal  interpretation. In the example below I added atrial flutter as the diagnosis, changing it from Kardia’s unclassified (Kardia’s algorithm calls anything it cannot clearly identify as AF that is over 100 BPM as unclassified.)

The ECG can then be archived or exported for entry into an EHR.

The benefits of this patient being connected
to me are obvious: we now  have an instantaneous patient-controlled method for knowing what his cardiac rhythm is doing whether he is having symptoms or not.

This knowledge allows me to make more informed treatment decisions.

The Kardia Pro Dashboard

When I  log into kardia pro I see this screen.

dashboard karia pro It contains buttons for searching for a specific patient or adding a new patient. Adding new patients is a quick and simple process requiring input of patient demographics including  email and birthdate.

From the opening screen you can click on your triage tab. I have elected to have all non normal patient recorded ECGS go into the triage tab.

Other Examples

Another patient’s Kardia Pro page shows that he records an ECG nearly every day and most of the time Kardia documents NSR in the 60s. Overall, he has made 773 recordings and 677 of them were NSR, 28 unanalyzed (due to brevity) , 13 unclassified and 55 showing AF.

Monitoring Rate  Control  In Patients With AF and Reversion Post-Cardioversion

Another patient I saw for the first time recently has had long-standing persistent AF.  His previous cardiologist performed an electrical cardioversion a year ago but the patient reverted back to AF in 40 hours.   Before seeing me he had purchased a Kardia mobile ECG device and was using it  to monitor his heart rate.

After he accepted my email invitation to connect via Kardia Pro I was able to see his rhythm and rate daily. The Kardia Pro chart belowshows his daily heart rate while in atrial fibrillation. We utilized this to guide titration of his rate controlling medications.  Such precise remote monitoring of heart rate in AF (which is often difficult to accurately assess by standard heart rate devices) obviates the need for office visits for 12 lead ECGs or periodic Holter monitors.

I performed a  second cardioversion on him after which he made  daily recordings documenting maintenance of NSR. With this system we can determine exactly when AF returns, information which will be very helpful in determining future treatment options.

Kardia Pro Plus Kardia Mobile ECG Creates Personal Intermittent Long Term Rhythm Monitor

There are many potential applications of the Kardia ECG device beyond AF monitoring (assessing palpitations, PVCs, tachycardia, etc.) but they are all enhanced when the device is combined with a good cardiologist connected to the device by Kardia Pro.

I’ve gotten spoiled by the information I get from my AF patients who are on  Kardia Pro now. When they call the office with palpitations or a sense of being out of rhythm I can determine within a minute what their rhythm is wherever I am (excluding tropical beaches and mountain tops)  or wherever the patient is (for the most part.)

On the other hand patients who are not on Kardia Pro have to come into the office for  12-lead ECGs. When they call I feel like my diagnostic tools are limited. Such patients usually end up getting one of the standard Long Term Monitoring (LTM) Devices. If I am fortunate, after a  few days to weeks , the results of the LTM will be faxed to my office.

I am optimistic based on this early experience with Kardia Pro that ultimately this service in conjunction with the Kardia Mobile ECG device (or similar products) will replace many of the more expensive and inconvenient long term monitoring devices that cardiologists currently use.

Skeptically Yours,

-ACP

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.

I pointed out that his previous  score was average for white men his age and his repeat score is also similar to the average white male of 71 years.

Entering Trump’s numbers into the MESA coronary calculator shows us he is at the 46th percentile, meaning that 46% of white men his age have less calcium.We can also calculate Trump’s 10 year risk of heart attack and stroke using the app from the ACC (the ASCVD calculator) and entering in the following information obtained from the White House press briefing:

Total Cholesterol          223

LDL Cholesterol            143

HDL Cholesterol              67

Systolic Blood Pressure 122

Never Smoked Cigarettes

Taking aspirin 81 mg and rosuvastatin (Crestor) 10 mg.

His 10 year risk of heart attack or stroke is 16.7%.

Given that his calcium score is average it doesn’t change his predicted risk and the conclusion is that his risk is identical to the average 71 year old white man-moderate.

We also know that Trump had an exercise stress echocardiogram which was totally normal and therefore can be reasonably certain that the moderate plaque build up in his arteries is not restricting the blood flow to his heart.

Here is what Dr. Jackson said about the stress echo:

He had an exercise stress echocardiogram done, which demonstrated above-average exercise capacity based on age and sex, and a normal heart rate, blood pressure, and cardiac output response to exercise.  He had no evidence of ischemia, and his wall motion was normal in all images. the stress echo:

The New York Times article on this issue, entitled “Trump’s Physical Revealed Serious Heart Concerns, Outside Experts Say”  however, presents a dramatically worrisome and misleading narrative.

It quotes several cardiologists who were very concerned about Trump’s high LDL level, weight and diet.

It’s interesting that some of the experts quoted in the NY Times piece feel that Trump’s Crestor dose should be increased in light of the recent NY  Times piece questioning whether the elderly should take statins at all.

If we have serious concerns about Trump’s heart then we should have the same concerns about every 71 year old white man because he is totally average with regard to cardiac risk. In addition he is on a statin and on aspirin, the appropriate drugs to reduce risk.

In contrast to the average 71 year old male he has had a battery of cardiac tests which show exactly where he stands cardiac wise.

Most of these cardiac tests we would not recommend to an asymptomatic individual of any age. Jackson revealed that Trump had an EKG and an echocardiogram.

His ECG, or commonly EKG, was normal sinus rhythm with a rate of 71, had a normal axis, and no other significant findings.

He had a transthoracic echocardiogram done, which demonstrated normal left ventricular systolic function, an ejected fraction of 60 to 65 percent, normal left ventricular chamber size and wall thickness, no wall motion abnormalities, his right ventricle was normal, his atria were grossly normal, and all valves were normal.

So our President has a normal heart for a 71 year old white male. This automatically puts him at moderate risk for heart attack and stroke over the next 10 years but he is being closely monitored and appropriately treated and should do well.

Nonalarmingly Yours,

-ACP

N.B. I see that Trump’s LDL was reported previously as 93. The current LDL of 143 suggests to me that he has not been taking his Crestor.

N.B. Below is an excerpt from my prior post which explains coronary calcium

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

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

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

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