Eric,

I am a huge proponent of stress echo but I also utilize nuclear stress rest perfusion imaging for lots of reasons:  LBBB patients, sedentary or diabled patients, folks with no echo windows, patients with SVT/Vtach in whom I don't relish dobutamine stress.  Additionally, stress echo is wonderful for patients with normal wall motion at rest when comparing normal resting to abnormal stress images BUT, I find nuclear more easily interpretable in patients with baseline wall motion abnormalities and infarct zones. Peri-infarction ischemia seems more precisely evaluated and far less subjecive with nuclear assessment.

As with all testing, the risk benefit ratio must be considered.  For patients and physicians who are concerned about radiation exposure, one can go to the ASRT (x-ray risk.com) website to calculate the risk of testing. Women have an inherent 37.5% risk of developing solid tumors in their ifetime due to background exposure (without nuclear testing of any type) and men 44.9%.  I calculated the risk of 10 nuclear stresses by age 50 and for my gender, my risk of cancer went from 37.5% to 38.135%.  If I had signifcant coronary disease, ongoing chest pain difficult to define, diabetes with potential for silent ischemia, etc. I would think the risk of adding only 0.635% risk of Cancer per lifetime would be worth it to assist in my coronary artery disease evaluation and management.

Having said that, indiscreminate testing of any type should be condemned. If anyone is aware of abuses in the system we should all make efforts i to combat that. I am especially concerned about patients incredibly undergoing serial exams on every six months basis or ambulatory folks undergoing a Lexiscan due to the convenience of being able to have physician extenders supervise the exams, etc.   In my very young patients who have  CAD, I've tried to utilze as much stress echo as possible and in those in which nuclear is the necessary modality, I've gone to every 2-3 years depending upon their symptomatology and risk factor profile. 

To combat radiation exposure, reimbursement for stress cine should match that of nuclear imaging. It takes just as long to train to read one as the other, both require techs and the benefit for the patients is the same. Perhaps adequate stress echo reimbursement might curb a tendency toward indiscriminate nuclear testing, 

Thanks for focusing on this absolutely necessary and interesting topic. 

Melissa 

As a non-invasive cardiologist and cardiac imager from a different healthcare environment (in the UK), I find your introduction to perpetuate the dogma against radiation based procedures that is gathering strength in the USA, particularly from those with vested interests in non-radiation based procedures.  

For instance, you state that myocardial perfusion scintigraphy exposes patients to ~40mSv, but in the UK and Europe diagnostic studies are readily achieved with exposures of ~8mSv.  Much as with CT, these figures are decreasing further as software and hardware development allow equivalent information with lower doses.  Of course, the USA enviroment appears to use many unecessary procedures, which should be condemned, but in a non-profit driven system, appropriate use of tests of coronary function can provide great benefit and shield patients from the even greater danger of unecessary invasive tests.  You suggest that the 43% normal coronary angiography rate recently reported in the USA is driven by prior functional testing but this is not the case since most of the prior tests were resting tests aimed at assessing LV function, such as resting echocardiography, and not ischaemia tests.  In London some call the strategy of direct to angiography without prior ischaemia testing the "Harley St" strategy, after the centre of London's private medical care.  

Remember also that we have little evidence that low exposures (<100mSv) are harmful and we simply adopt the linear no-threshold hypothesis for radiation harm in order to assume the worst on behalf of our patients.  The concept of hormesis and even Darwinian evolution would support an alternative view, that low doses of radiation may not be as harmful as we assume and may even be beneficial.  We have evolved for millions of years in an environment exposed to ~2mSv per year and it would be odd if our DNA repair mechanisms had not also evolved to adapt to this level of exposure.  

However, there is doubt and so no-one would argue against using a non-radiation based test if identical information with identical reliability can be provided otherwise. Unfortunately, that is often not the case and few institutions are lucky enough to have all techniques available at expert level.  I would therefore argue that the new and growing breed of cardiac imagers with expertise in a number of techniques should be our patients' guardians in directing them to the most appropriate test for their circumstances, and that these decisions should operate in an environment as far as possible removed from conflict of interest emanating from some single technique imagers.  

Having said all of that, thanks for initiating what I hope will be a stimulating and influential discussion, even if from a (deliberately?) polarised introduction.  

The original comment is rather selective of the facts, and leads to an inappropriate conclusion.

If you trawl through sufficiently old data, you will include patients who were assessed with thallium myocardial perfusion scans. The radiation does is at least 3x that of technetium based agents which give superior results. Thus if you wish to, you can generate some spectacularly bad statistics for radiation dose exposure.

However, as one of the writers above has noted, the risk is dwarfed by the cardiac event risk. In addition, if you are realistic and only include technetium based agents then the dose becomes reasonable. However, some of the readers may not be aware there has been a revolution in processing software which allows half or quarter dose. This software can be obtained as an upgrade from the vendor (e.g. GE) or from a third party source - for any, including older, equipment. There is plenty of evidence that it works.

 In addition, if the patient has normal coronary arteries this should be obvious from a single "stress" study, thus avoiding the second "rest" study. There is good evidence that this approach works. Finally, sensitivity is significantly improved by using sophisticated wall motion analysis (which is how stress echo works exclusively).

Thus good, robust results can now be obtained with 4mSv (perhaps 2mSv?), which 15 years ago took 30mSv. There is now no reason to avoid myocardial perfusion scanning because of dose considerations.

 

We always welcome new information and recommendations.  I would like to share with your reaaders our studies in the US and now in ANZ.  A single injection of sestamibi with multiple measurement of activity post stress is more accurate than two injection rest and stress approach.  This has the double benefit of reducing the amount of radiation administered to the patient and also staff, with improved diagnostic accuarcy.  RMF

QUESTION FOR DR. TOPOL-- WILL SCIENCE TRUMP POLITICS

     Professor Richard Underwood states, "we have little evidence that low exposures (<100mSv) are harmful and we simply adopt the linear no-threshold hypothesis for radiation harm in order to assume the worst on behalf of our patients.  The concept of hormesis and even Darwinian evolution would support an alternative view, that low doses of radiation may not be as harmful as we assume and may even be beneficial." This statement is highly misleading!  The hormesis thesis has been thoroughly discounted by most  leading medical physicists and radiologists.  He then claims the linear no-threshold model overstates the risk when, in fact, it understates risk. The BEIR VII committee reported there is no safe dose, right down to zero, and 15 cancer experts, including the UK's Richard Doll and Dudley Goodhead and Dale Preston, head of the A-bomb Life Span Study, concluded there is good epidemiological evidence for increased cancer risk at acute doses of 10-50 mSv and at protracted doses of 50-100 mSv (PNAS 2003;100:  13761-13766).

      The ECRR (European Committee on Radiation Risk 2010), composed of 45 low-dose  experts from 12 countries, has published its recommendations on health effects from exposures at low dose and challenges the widely accepted linear model used in standard-setting by the International Commission on Radiological Protection. This model has been adopted by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation and the IAEA (International Atomic Energy Agency). ECRR points out that the ICRP model is based solely upon external radiation doses and "falsely uses data from one set of conditions-- high-level, acute, external exposure-- to model low-level, chronic, internal exposure, a procedure that is scientifically bankrupt, and were it not for political considerations, would have been rejected long ago."  ECRR proposes a supralinear or biphasic cell-response model with a sharply higher risk curve at low-dose exposures, one that independent scientists are beginning to embrace.

     In our paper on excess lifetime fatal cancer yield attributable to 6.5 million abdominal CT scans in the pediatric age-band (this medical reporter is corresponding author) we used 2006 data and estimated 58,000 future fatalities at 10 mSv per scan and 116,000 at 20 mSv. From a study by Fred Mettler et al on multiple scans we found a mean organ dose of 28 mSv (Bertell R, Ehrle LH, Schmitz-Feuerhake I. Int J Health Services 2007;37(3):419-439). Clearly, very low dose poses a significant public health risk, particularly since there were at least 75 million CT examinations in 2010, not including multiple scans at the same examination.

     A further challenge to the conventional wisdom is contained in a meta-analysis of 2000 papers by Russian biologist Alexey V. Yablokov and two colleagues (ANNALS of the New York Academy of Sciences, November 2009, Chernobyl: Consequences of the Catastrophe for People and the Environment, available free full text at university libraries. It estimates non-cancer diseases and cancer as well as radioactive impact on flora, fauna, microbial biota, air, water, and soil over a wide area, including Europe, the UK, and Scandinavia

     Dr. Topol is spot on with his concerns relating to increased exposures from nuclear scintigraphy. Radiation workshops and CMEs should be manditory for all cardiologists, and radiation issues should be part of the medical school armamentaria, not just for medical physicists and radiologists. Ever since Hiroshima and Nagasaki, along with the ascendancy of nuclear power, radiation issues have been highly controversial. Now radiologists and medical physicists have raised the bar with consensus at some conventions with agreement that about one-third of all CTs are unnecessary.

Keep the pressure on, Eric. Science may yet trump politics!

Lynn Howard Ehrle, M.Ed, consumer law / economics teacher (ret)                            Senior Biomedical Policy Analyst (pro bono), Organic Consumers Association            Founder and Chair, International Science Oversight Board (INSIGHT), composed of 43 physicians, scientists, and policy analysts from 11 countries, including 17 low-dose radiation experts                                                                                          Memberships:  Radiation Research Society; National Writers Union; AFT & NEA(ret); American Association for the History of Medicine                                                  E-mail:  ehrlebird@organicconsumers.org                                                           Based in Plymouth, Michigan

 

 

 

 

 

This is a very complicated issue.My opinion is that all the diagnostic armamentarium should be used with wisdom and according to the single cases. I would like to add a few more points:

1. plain ecg exercise has still its role in the appropriate situations (most)
2. in the eligible patient stress echo is useful if the post test decision is made by the stress operator. I very rarely have surprises when I decide after a stress echo performed by myself or by another cardiologist I know very well. If you are performing a stress echo and don’t “see” very well and you have also to take the consequent decision on that particular patient, you are more prone to admit that you need an additional test. On the contrary myocardial perfusion scintigraphy comes with static images, and can be easily evaluated even on paper and the cardiologist may disagree with the nuclear physicians about the diagnostic conclusions.
3. perfusion scintigraphy is often superior in patients with poor echo window, as many coronary patients have. Yes, you have the radiation burden, but you may avoid coronary angiography (or have it, often with benefits).
4. individualize tests for the single patient. Diagnostic question, patients’ age, gender, symptoms, patients’ occupation, co-pathologies, disease stability, who is performing the tests, availability and comparability of previous tests, potential litigations, efficiency of the available equipments, etc.. should all be taken into account. With the great availability of tests, the right one should not be missed
5. outside cardiology, I also see too many tests, often repetitive, especially in oncology. My personal idea is that this attitude might depend from strict adaptation to “protocols”, defensive medicine and multiple physicians patients’ management.

A few reasons why:

1) Despite the "data" my experience (and that of my colleagues in very different institutions and locations) is that perfusion imaging has greater sensitivity than stress echo (and plain treadmill stress testing of course as well).  A false positive test with subsequent normal angiography is far better accepted by the patients than a false negative.

2)Reimbursement, reimbursement, reimbursement: Now this is not only because of the high reimbursement for nuclear imaging, but the incredibly low (below cost if opportunity cost of time is factored in) reimbursement for all other forms of evaluation.

If we wanted to be accurate, prospective gated multislice CTA in the appropriate patient with the appropriate protocols is not far different exposure-wise, and is proving to be more accurate than nuclear or echo imaging. It is cheaper by far than nuclear imaging, but because it is a newer test, the insurance companies crack down on it. In my practice, I find I have far fewer repeat tests or subsequent "negative" caths when I can start with CTA. Of course this is dictated by the insurance companies policies, though of course, they are "just dictating reimbursement, not practicing medicine."

The big question is should we do stress tests at all?

Have they ever been shown to save lives or decrease heart attacks?

Risk stratification is the worst argument I have heard to justify these tests.

How many patients that undergo stress test know that the test is being done only to tell them of their 10 year risk of cardiovascular events and performing that test has never in any randomizedd study shown to decrease their chance of having a heart attack? Look at all the preoperative stress testing data for example.

People argue aggressive risk factor reduction, for high risk patients- but where is that data. You have to show me a randomized study where aggressive risk factor modification did not benefit/harmed people with normal stress test, for me to believe this argument. Plus the argument of lipid goals is also very wrong because all lipid trials were done with fixed dose pills and not treating to a certain target. Why not use maximal LDL reduction in patients who have more clinical risk factors.

In patients with true angina, proceed to cath and do an FFR if you are not sure. In patients with atypical chest pain, do no further invasive tests, because if they dont have true angina, the COURAGE trial would tell you that nothing else would improve for them if you stent anything you find.

I welcome your comments.

Then, you should define what is "true/untrue angina". You have someone in your office complaining of chest pain, I suppose you have to test that patient. There is also the chapter of silent ischemia to keep in mind. You don't need "heart attacks". A sufficiently long ischemic episode can trigger arrhythmias and sudden death. I try to avoid such problems to patients, this is what I am paid for. You don't need a trial to know that if you jump from an airplane with a parachute you have better chances to survive.

In Switzerland, nuclear cardiology is usually performed by radiologists and the false positive rate is relatively high, because obviously, there is a fear to miss coronary artery disease. I have performed - as a unique opportunity in Switzerland - more than 5'000 nuclear scans and I have the opportunity to perform stress echo, which I teached myself by doing a stress echo in all patients referred for a nuclear scan. Using this approach, my false positive rate dropped to about 10%, further I rarely use nuclear in my practice based work, but stress echo. I use a single rest/stress sestaMIBI protocol which exposes patients to radiation with about 8 mSv. At the University of Basle, about 2000 nuclear scans are performed, but when cardiologists come down to real world cardiology they simple have no idea how to perform a stress echo, because there was no teaching - e.g. same time imaging with nuclear. So the problem is teaching. I receive nuclear scans from about 20 referral centers and often I ask myself, why did they not perform a stress echo first as a gate keeper for nuclear. The answer is: no skills. Imaging cardiology - at least in Switzerland - is driven by fancy imaging techniques - such as hybrid imaging, but these guys do not know how to do a stress echo. At the large scale, population level, we need much more cardiologists who are able to perform a stress echo. If universities do not offer teaching in that field, nuclear and CT will win the battle. Sadly enough. Finally: to send a patient to the cath lab without relevant ischemia present, is not ethical (in view of stentomania and plaque sealing advocates among invasive cardiologists). 

reducing patient and staff radiation exposure
Apart from the general concern, we have been addressing the issue of actual reduction in patient radiation dosage with improved detection of heart disease. This work has been presented and published in multiple papers over the last decade showing that Sestamibi Redistribution evaluation allows for improved detection of disease. That prior methods for detecting this have failed to focus on comparing multiple post stress images which can unmask hidden ischemia is due to the failure to recognize this effect. By using this protocol we have both demonstrated a significant improvement in detection of severe disease while additionally reducing staff and patient radiation exposure. This work has been conducted at 5 different sites and this approach has been confirmed by multiple other studies including recent work performed at UCLA and Harvard.

This approach provides us with a new Standard of Care and can be used with both the older SPECT cameras and we believe the newer D-Spect cameras. The method employeed is simple and consistent with the original methodology described in 1925 by Blumgart, et al.

A sample of the work published in the U.S., Asia and Europe is presented below.

Fleming RM, Harrington GM, Baqir R, Jay S, Sridevi Challapalli, Avery K, Green J. The Evolution of Nuclear Cardiology takes Us Back to the Beginning to Develop Today’s “New Standard of Care” for Cardiac Imaging: How Quantifying Regional Radioactive Counts at 5 and 60 Minutes Post-Stress Unmasks Hidden Ischemia. Methodist DeBakey Cardiovascular Journal (MDCVJ) 2009;5(3):42-48.

Fleming RM, Harrington GM, Baqir R, Jay S, Challapalli S, Avery K, Green J. Renewed Application of an Old Method Improves Detection of Coronary Ischemia. A Higher Standard of Care. Federal Practitioner 2010;27:22-31.

Fleming RM. The Nuclear Imaging Uncertainty Principle. Do Nuclear Cameras Really Work? Nature Precedings 14 October 2010

Fleming RM. Inflammation and Heart Disease. The Wisdom of listening to our Colleagues! Ann Intern Med 19 October 2010.

Fleming RM, Harrington GM. Sestamibi Redistribution Identifies Vulnerable Coronary Plaques. The State of the Art! Ann Intern Med 21 October 2010.

Fleming RM. Defining Dietary Outcomes Based Upon End Organ Damage. Annals of Intern Med 18 November 2010.

Fleming RM, Harrington GM. FHRWW stress SPECT protocol reduces radioactive dosage and increases ischemia detection. ANZ Nuclear Medicine 2010;41(4):18-26.

Fleming RM, Harrington GM, Jay S, Avery K. FHRWW Rest SPECT Viability Imaging – Cardiac viability measured using resting FHRWW Redistribution of Sestamibi: The Scientific Evidence proves “Sestamibi is not Superglue.” ANZ Nuc Med March 2011 (in press).

“Study: Nuclear stress tests need to be simplified.” SNM SmartBrief, July 23,2010.

WEB EXCLUSIVES Feature: “Single sestamibi injection may suffice for ischemic detection”. HealthImaging.com 4 August 2010.

I am surprised by the civility of this thread and am afraid that it understates the problem - so here goes...

I am a general and interventional cardiologist board certified with the subspecialty designation and I can comfortably state that more than 50% of nuclear stress tests are ordered for no good reason. Risk stratification in the absence of symptoms and angiographic evaluation and treatment has never been shown to be effective or cost beneficial.  Concocting symptoms (dyspnea on exertion as an ischemic equivalent) is another favorite.  I have on many occasions interviewed patients prior to referred procedures only to discover that they did not have any symptoms regardless of what was documented in the clinical record - it is clear that cardiologists have been trained to do nuclear studies and then to recommend revascularization based on those results.  Those who deny this are not living in the real world.  Some of the problem is monetary however with the steep decline in reimbursement I do not see a decline in testing so it is more than that.  Paranoia perhaps.  Patient expectation - most certainly.  It would be pretty simple to identify the outliers in nuclear stress testing (or any testing for that matter) using the Medicare database and then subject those outliers to a "morning report" type interrogation - if that makes you uncomfortable than you are part of the problem.  I was trained to be able to defend every action I take as a physician and to expect nothing less from my colleagues.  That is what our profession demands and our patients deserve.

One of the many problems that leads to overutilization is that guidelines are written by cardiologists who publish in the field, the "experts" whose enthusiasm promotes the utility of some diagnostic procedure.  This is an obvious conflict of interest.  A second problem is that writing guidelines to integrate information across fields (echo, nuclear, CTA, MR) is not seriously undertaken.  A third problem is that guidelines are incredibly and unnecessarily complex, and thus often rendered inapplicable.  Just look at the ACC guidelines. 

Instead, our college could state an integrated simple guideline like:

When suspecting ischemia, always start with a stress echo to avoid the radiation exposure of stress nuclear and CTA, the limited predictive value of plain treadmill exercise, and the expense and gadolinium exposure of MR stress studies.

In this way we could limit extraneous motivations for test ordering.

 

 

 

 

 

I am shocked by the numbers!  The sad reality is that nuclear stress tests and echo exams provide cardiologists with profits so that they can afford to loose money talking to patinets.  When testing is needed for existance, it is amazing how easy it becomes to justify testing.

 

Seven years ago, I used exercise stress testing to assess risk among my patients.  Eight exercise tests a week translated into two or three nuclear tests.  Then I discovered coronary calcium imaging.  

 

Today, I do about five stress tests a year.  I use coronary calcium imaging to identify subjects at risk and initiate preventive therapy prior to the onset of symptoms.  The result is that I have seen a 90% reduction in heart attacks and strokes over the last 6 years.  

 

The statistics sited in this study would show that for the cost of what we are spending on nuclear stress tests, we could afford to do calcium imaging on every adult above age 40 every three years and still have about six billion dollars left over at the end of the day.  Doing 30 million heart scans every year would give the population about one third of the radiation that is currently delivered by nuclear imaging.  

 

If we did calcium imaging and determined who does and who doesn't have risk for MI and treated those with risk and did not subject those without risk to the potential toxicity of statin medications, how different the outcomes would be! 

Eric - the theme is constant ...overuse of "technology" ( echo, nuc.,cath and stents).

Reasons :            1.Reward          2. Poor training/practice by doctors. 

Solution  :            Address  1 & 2 .

     ss