Beware the "false positive" stress test

There's a widely-known (among cardiologists) problem with nuclear stress tests. It's called the "false positive." (Nuclear stress tests are known as stress Cardiolites, stress thalliums, stress Myoviews, persantine stress tests, adenosine stress tests)

Stress tests, nuclear and otherwise, are helpful for identifying areas of poor blood flow. If an area of poor blood flow is detected and the area is substantial, then there may be greater risk of heart attack and other undesirable events in the relatively near future.

What "false positive" means is a stress test that shows an abnormality but it's not true--it is falsely abnormal. There are a number of reasons why this can happen. The problem is that this phenomenon is very common. Up to 20% of nuclear stress tests are false positives.

There are indeed situations where there may an abnormality and it is not clear whether it is true or false. This may lead to a justifiable heart catheterization or CT coronary angiogram. But, given the extraordinary number of false positives, there's a lot of gray in interpreting these tests. Hospital staff, in fact, call nuclear medicine "unclear" medicine. It's common knowledge that you can often see just about anything you want to see on a nuclear image of the heart. Abnormalities in the bottom of the heart, the "inferior" wall, are especially common due to the overlap of the diaphragm with the heart muscle, yielding the appearance of reduced blood flow. Defects in the front of the heart heart are common in females with large breasts for the same reasons.

The problem: The uncertainty inherent in nuclear stress tests opens the door to the unscrupulous or lazy practitioner. Any blip, tick, or imperfection on the nuclear images serve as carte blanche to drag you into the hospital for procedures.

This abusive practice is, in my experience, shockingly common for two reasons: 1) It pays better to do heart catheterizations, and 2) Defensive medicine.

What's the disincentive? Only doing the right thing and maintaining a clear conscience. Slim reasons for many of my colleagues--and a lot less money.

If you are without symptoms and feel fine, and a nuclear stress test is advised by your doctor, followed by a discussion of an abnormality, insist on a discussion of exactly what is abnormal, just how abnormal, and what the alternatives might be. If you receive unsatisfactory or incomplete answers despite your best effort, it's time for another opinion.

Don't neglect your magnesium

Magnesium is kind of boring. So most people don't pay too much attention to it.

Magnesium can be important, however. I saw an interesting phenomenon recently. A type I diabetic patient of mine (that is, an adult who developed diabetes as a child), Mitch, was experiencing wide swings in blood sugar: low low's and very high high's (300-400 mg/dl). Mitch's magnesium was only marginally low at 2.0 mEq/L. (Ranges for normal magnesium blood levels are usually 1.3–2.1 mEq/L or 0.65–1.05 mmol/L.) Note that Mitch's blood levels fall within "normal." I do not agree with these "normal" ranges. I shoot for 2.1 to 2.4 mEq/L, which I think is the truly normal range.

In addition to eating plenty of raw nuts and green vegetables, Mitch began supplementing magnesium with magnesium citrate, 200 mg twice a day (our preferred supplement form). He reported that the wide swings in blood sugar were nearly eliminated.

Mitch's dramatic benefit is just a great illustration of how magnesium can help control blood sugar metabolism. A type I diabetic is more sensitive to the effects, but anyone with type II (adult) diabetes, metabolic syndrome, or just a slightly high blood sugar could benefit from magnesium supplementation.

There's a number of ways to accomplish getting sufficient magnesium in your daily regimen. Track Your Plaque members, Be sure to read:


Your water may be killing you at
http://www.cureality.com/library/fl_03-002magnesium.asp

Magnesium: Water to the rescue! at http://www.cureality.com/library/fl_03-010magnesium2.asp

Third heart scan a charm

It struck me recently that, for many people, it's not the second but the third heart scan that more commonly shows a reduction in score.

I think this is because many people's reaction to their first heart scan is "This can't be. There's no way my arteries have that much plaque." They then follow a half-hearted program to correct their patterns.

When the second heart scan shows a significantly higher score, that really catches their attention. This is when they finally buckle down and give it their all.

Only the occasional person will, after the first heart scan, seize full control and take their program very seriously. These tend to be highly motivated people.

Don't feel too bad if your second heart scan score shows an increase. Look at it for what it represents: feedback on the adequacy of your program.

Metabolic syndrome--cured

Peter started out at age 59 at 248 lbs, standing 6 ft tall (BMI = 33.6!).

Along with his weight, Peter had the entire panel of phenemena of the so-called "metabolic syndrome", or pre-diabetes:

--Triglycerides 238 mg/dl and associated with extremes of excess VLDL and IDL
--High blood pressure
--Blood sugar 115 mg/dl
--High c-reactive protein
--Small LDL particles 99% of total LDL

Interestingly, Peter's HDL was a surprisingly favorable 58 mg/dl (HDL is usually low in this syndrome). However, when broken down by size, he had nearly zero large, healthy HDL (sometimes called HDL2b). Though total HDL was favorable, most of it was simply ineffective.

Peter eliminated snacks and processed foods, particularly bread; increased his reliance on healthy oils and lean proteins; incorporated soy protein; increased vegetables. He added 30 minutes of a rapid walk on a treadmill every day. He added vitamin D to achieve a blood level of 50 ng/dml. He added a magnesium supplement.

Peter has lost 31 lbs. in the last year. Weight 207 lbs., BMI 28.1 (desirable <25). Blood sugar: 96 mg/dl; triglycerides: 56 mg/dl; HDL 71 mg/dl with 35% in the large fraction; small LDL 45% of total. Not perfect, but a damn site better.

Control of metabolic syndrome is an achievable goal for over 90% of people, just with these simple efforts. We haven't yet had a chance to assess the effect on the progression or regression of Peter's heart scan score, but he has, at the very least, spared himself a future of diabetes and all its complications.

Heart Scan Curiosities #6
















This is a "slice" from a normal heart scan in a 58 year old woman. Heart scan score zero. Look at the lungs, the dark areas left and right of the heart in the center. The lungs are also normal. Black represents normal density, healthy lung tissue. The white streaking is just normal lung blood vessels. This person doesn't smoke.


















This woman smokes a pack of cigarettes a day and has done so for 45 years ("45 pack-years"). She had a surprisingly low heart scan score (at age 64) of only 71, despite the smoking. However, look at this woman's lungs. It's a little tough to make out, since the computer graphics loses some of the resolution. But you can see the near absence of lung tissue on both sides. This is an advanced phase of the destructive lung disease, emphysema, from smoking. Even if she quit smoking today, the destroyed lung tissue never grows back. She literally has huge gaps or holes in her lungs where lung tissue used to be.

Smoking is among the most destructive, terrible things you can do to your body, short of swallowing strychnine or jumping off a building. Stay as far the heck away from cigarettes as you possibly can. If you are exposed to "secondary" smoke, insist that the person never smoke in your presence. It's not the smell that destroys your lungs or causes coronary plaque (though it is indeed foul), it's the actual smoke.

Should you become a vegetarian?

Do you need to become a vegetarian in order to reduce your heart scan score?

No. Plain and simple. We’ve had many non-vegetarians drop their scores.

That said, are there still advantages to following a vegetarian diet, or some variation on the vegetarian theme?

Yes, there are. Let’s put aside the moral or religious arguments in favor of not eating animals—the need to eliminate killing animals for food, elimination of suffering common in modern livestock practices, Kosher considerations, etc. (Not that there aren’t real arguments here. Our focus for this conversation is not, however, the moral dilemma, but the health argument.)

Some of the most unhealthy people I’ve ever met, mostly males, are proud carnivores who boast of their prodigious capacities to eat meat. Unfortunately, it’s hard to tease out the ill-effects of excessive meat eating, since these same men also tend to be substantially overweight, smoke, drink excessively, and fail to get exercise unless their job is physically demanding. You know the type.

What advantages does a vegetarian obtain? A number of studies have suggested that the reduced saturated fat, reduced exposure to parasites, as well as reduced exposure to the antibiotics and hormones now used routinely in livestock-raising practices, do indeed provide benefits to the vegetarian. Thus, vegetarians tend to be substantially thinner, experience less bowel cancer, have less diabetes and heart disease, and live longer.

(If you are interested in reading or seeing more about just how inhumane modern livestock practices are, take a look at the video, "Meet Your Meat" at meat.org. Be sure not to view this after dinner.)

Of course, some of the disadvantages of eating animal products diminish when free-range livestock are eaten, i.e., livestock not raised in the inhumane cramped, filthy conditions of livestock factories, but in the open, grazing or rooting freely. These animals tend to have different fat compositions and taste different.

The advantages of vegetarianism, however, have blurred in recent years, since many so-called vegetarians have failed to maintain the distinction between naturally-occurring foods and processed foods. So, Ritz Crackers, Oreo cookies, whole wheat bread, and Raisin Bran fit into a vegetarian program, but they’re awful for your health. I’ll occasionally meet a self-proclaimed vegetarian who looks every bit as unhealthy as a conventionally eating American, that is, overweight, pre-diabetic person with a developing heart scan score.

So it is not necessary to be vegetarian to reduce your score. You might consider vegetarianism for other reasons, such as moral considerations, or to reduce your risk for cancer. But it is not necessary to drop your heart scan score. A non-processed food diet? Now that's is worth giving serious consideration.

Let's make it a lot easier

The American Heart Association just released a new set of consensus guidelines on heart disease prevention in women: Evidence-Based Guidelines for Cardiovascular Disease Prevention in Women: 2007 Update

For those of you following the Heart Scan Blog and the Track Your Plaque program, there will be little new in the guidelines. In fact, you'll wonder if the date on the front of the report should be 1987, rather than 2007. Did you know that you should exercise and eat healthy?

Take a look at the list of risk factors for coronary vascular disease (CVD) listed in the report:

Major risk factors for CVD, including:
Cigarette smoking
Poor diet
Physical inactivity
Obesity, especially central adiposity
Family history of premature CVD (CVD at <55>

Progress: You'll notice that buried inside the list is "Evidence of subclinical vascular disease (e.g., coronary calcification)". Just a few short years ago that wouldn't have even been included.

The Track Your Plaque contention is that, for the great majority of women, this list could be shortened to one item: coronary calcification. As time goes on, the people who argue and draft these guidelines will come to the realization that coronary calcification is the disease--it's not a risk for the disease, a predictor of the disease. Coronary calcification is the disease itself. The other items on the list recede way into the background when you know whether or not coronary atherosclerosis is present, i.e., you know your heart scan score (of coronary calcium).

The report goes to say such things as taking a little bit of fish oil is a good idea, maintaining a normal blood pressure is desirable. . . yada yada yada. You've heard this all before.

A major part of the treatment guidelines are devoted to LDL cholesterol reduction with statin agents. You shouldn't be surprised. It's amazing what $22 billion dollars in revenues will buy.

A closing paragraph reads:

'Population-wide strategies are necessary to combat the
pandemic of CVD in women, because individually tailored
interventions alone are likely insufficient to maximally prevent
and control CVD. Public policy as an intervention to
reduce gender-based disparities in CVD preventive care and
improve cardiovascular outcomes among women must become
an integral strategy to reduce the global burden of
CVD.'


Say that again? If you understood that bit of gobbledygook, you're a lot smarter than me.

Don't look to the American Heart Association report for any new ideas. It reminds me of the politician who reminds everybody of what a devoted family man he is: It has nothing to do with his policies. It just makes him look good. If compared to prior report, the 2007 report does indeed represent progress--but just oh so little.

No wonder nobody talks about real prevention

Take a look at this eye-opening statement taken from a well-written NY Times article about Dr. Arthur Agatston, the South Beach Diet and now South Beach Heart Program books:


'We have made major improvements in prevention,” Dr. Gregg W. Stone, the director of cardiovascular research at Columbia University, says. “But it’s difficult. It takes frequent visits, a close relationship between a physician and a patient and a very committed patient.'

Which is exactly the atmosphere Dr. Agatston’s practice tries to create. Nurses there give patients specific cholesterol goals to meet and help them deal with the side effects of the drugs they are taking. A nutritionist, Marie Almon, meets with patients frequently enough to discuss real-life issues like how to stick to a high-fiber Mediterranean diet even on a cruise or a business trip.

There is only one problem with this shining example of a medical practice: it is losing money.



From NY Times, January 24, 2007. What’s a Pound of Prevention Really Worth? (Find the full text at http://www.nytimes.com/2007/01/24/business/24leonhardt.html?ex=1172379600&en=4268a738e82857da&ei=5070.)

It gets at one of the fundamental reasons why your cardiologist will probably never talk to you about an intense approach to prevention: it doesn't pay. Because John Q. Cardiologist focuses, instead, on how to increase procedural volume, train how to put in the next best defibrillator, etc., there is little consciousness about preventive issues. Just the simple matter of taking fish oil causes their eyes to glaze over.

That's why the Track Your Plaque program exists: it is a portal for the kind of information you cannot get. Of course, you could read all the scientific studies, attempt years of trial and error, and try to gain a sense of how to do this yourself. Or you could follow this program. We are proud to not worry about generating procedural profits. We ar unbiased by drug or medical device money. We say exactly what we mean.

By the way, we are on a current push to really "beef-up" our online discussions via real-time chat. Long-term, we'd like to be able to offer chat with our staff many hours every day. Be patient. It will happen, but not today.

HDL and vitamin D

I know of no published reports on this question, but I've now seen numerous people experience significant jumps in HDL with raising blood vitamin D to 25-OH-vitamin D3.

Last week, for example, I had a man who had struggled with raising HDL from a starting level of 28 mg/dl. On niacin, exercise, weight loss, fish oil, red wine, and cilostazol (a prescription agent that I use occasionally that raises HDL), his HDL rose to 41 mg/dl--better, but hardly to our goal.

I added vitamin D, 4000 units, and raised his 25-OH-vitamin D3 level from 22 ng/ml to 53 ng/ml. Next HDL: 73 mg/dl! Small LDL improves along with a rise in HDL.

Not everybody's response is this dramatic. I see more typical rises of 5 to 10 mg/dl every day. I'm uncertain of why the response is inconsistent, though people who begin with lower vitamin D levels seem to experience a larger HDL increase. I wonder if the partial normalization of insulin and glucose responses is at work, or some anti-inflammatory effect.

Vitamin D provides so many other benefits, as well as HDL-raising. I hope you've gone to the effort to have your blood level checked to determine your replacement need. If not, now's the time. February represents your nadir (lowest point) for 25-OH-vitamin D3 blood levels.

Even more Michael Pollan

"Eat food. Not too much. Mostly plants.

That, more or less, is the short answer to the supposedly incredibly complicated and confusing question of what we humans should eat in order to be maximally healthy. I hate to give away the game right here at the beginning of a long essay, and I confess that I’m tempted to complicate matters in the interest of keeping things going for a few thousand more words. I’ll try to resist but will go ahead and add a couple more details to flesh out the advice. Like: A little meat won’t kill you, though it’s better approached as a side dish than as a main. And you’re much better off eating whole fresh foods than processed food products. That’s what I mean by the recommendation to eat “food.” Once, food was all you could eat, but today there are lots of other edible foodlike substances in the supermarket. These novel products of food science often come in packages festooned with health claims, which brings me to a related rule of thumb: if you’re concerned about your health, you should probably avoid food products that make health claims. Why? Because a health claim on a food product is a good indication that it’s not really food, and food is what you want to eat."


Michael Pollan, author of my latest favorite book, The Omnivore's Dilemma, wrote a wonderful piece for the New York Times entitled "Unhappy Meals". You can find the full text at http://www.nytimes.com/2007/01/28/magazine/28nutritionism.t.html?ex=1172120400&en=a78c20f4da0cdc7b&ei=5070. (Another favorite read of mine, The Fanatic Cook's Blog at , alerted me to Pollan's article. Incidentally, take a look at the Fanatic Cook's latest posts--very entertaining and informative. She's got incisive insight into foods as well as a great sense of humor.)

Pollan goes on to say that...

"...typical real food has more trouble competing under the rules of nutritionism, if only because something like a banana or an avocado can’t easily change its nutritional stripes (though rest assured the genetic engineers are hard at work on the problem). So far, at least, you can’t put oat bran in a banana. So depending on the reigning nutritional orthodoxy, the avocado might be either a high-fat food to be avoided (Old Think) or a food high in monounsaturated fat to be embraced (New Think). The fate of each whole food rises and falls with every change in the nutritional weather, while the processed foods are simply reformulated. That’s why when the Atkins mania hit the food industry, bread and pasta were given a quick redesign (dialing back the carbs; boosting the protein), while the poor unreconstructed potatoes and carrots were left out in the cold.

Of course it’s also a lot easier to slap a health claim on a box of sugary cereal than on a potato or carrot, with the perverse result that the most healthful foods in the supermarket sit there quietly in the produce section, silent as stroke victims, while a few aisles over, the Cocoa Puffs and Lucky Charms are screaming about their newfound whole-grain goodness."


Not everything Pollan says is new, but he says it so eloquently and cleverly that he's worth reading. If you haven't yet read Omnivore's Dilemma, or just want a condensed version of the book, the New York Times piece is a great piece of the world according to Michael Pollan.
"Heart scans" are not always heart scans

"Heart scans" are not always heart scans

Beware of the media reports now being issued that warn that "CT heart scans" pose a risk for cancer.

One report can be viewed at
http://www.webmd.com/cancer/news/20070717/ct-heart-scan-radiation-cancer-risk.

This was triggered by a Columbia University study of risk for cancer based on the dose of radiation used in CT coronary angiograms. Theoretically, exposure to the radiation dose of CT coronary angiography can raise risk for cancer by 1 in 143 women if radiated in their 20s just from that single exposure.

If you've been following the Track Your Plaque discussion, as well as my diatribes in the Heart Scan Blog, you know that the media got it all wrong. The "heart scans" they are referring to are not the same as the heart scans that we discuss for the Track Your Plaque program.

A conventional heart scan (of the sort we refer to) exposes the recipient to 4 chest x-rays of radiation if an EBT device is used, around 8-10 chest x-rays of radiation if a 64-slice CT scanner is used. For the quality of information we obtain from these screening heart scans, we feel that it's an acceptable exposure.

The "heart scan" this study and subsequent reports refer to is not truly a screening heart scan, but a CT coronary angiogram, or CTA. CTAs are performed on the same CT or EBT devices, but involve far more radiation. CTA exposes the recipient to about 100 chest x-rays of radiation on a 64-slice device (more or less, depending on the way it is performed.) Just a couple of years ago, some centers were performing CTA on 16-slice devices, a practice I and the Track Your Plaque program vocally opposed, since up to 400 chest-rays of radiation were required! I even called a number of centers advising them that they were putting the public in jeopardy. CTAs also require injection of x-ray dye, just like any conventional angiogram.

CTA on 64-slice CT scanners require the same radiation exposure as a conventional heart catheterization, an issue glossed over in most conversations. In other words, the test that many of my colleageus so casually recommend poses a similar risk.

The message: the test I advocate for screening for coronary heart disease is a CT or EBT heart scan, not a CT coronary angiogram. CTA is a useful test and will get better and better as the engineers discover ways to reduce radiation exposure. But, in 2007, CTA is a diagnostic device, not a screening device. If you require an abdominal CT scan because your doctor suspects pancreatic cancer, or a CT scan of the brain because you might have a life-threatening aneurysm causing double-vision or seizures, it would be silly to not undergo the scan because of long-term and theoretical cancer risk.

But undergoing a CT coronary angiogram for screening purposes is ridiculous with present technology. I've said it before and I will say it--shout it--again:

CT coronary angiograms are not screening procedures; they are diagnostic procedures that should be taken seriously and do indeed pose measurable risk for cancer, a risk that is presently unacceptable for a screening test.

You wouldn't undergo a mammogram to screen for breast cancer if it exposed you to 100 chest x-rays of radiation, would you? Screening tests should be safe, reliable, accurate, and inexpensive. CT coronary angiography is none of these things. Genuine heart scans--the kind the Track Your Plaque program talks about and relies on--is all of those things.

Comments (6) -

  • Anonymous

    7/19/2007 12:16:00 AM |

    Dr. Davis, would you please specify the millisievert values you are assuming for chest x-ray, EBCT Ca score, MSCT Ca score, and CT angiogram? I just got a 64-slice Ca score and they told me I received an effective dose of 2 mSv. Would a CT angiography typically result in 20 mSv?

  • Dr. Davis

    7/19/2007 12:59:00 AM |

    Hi,

    Please see my Blog post, CT scans and radiation exposure at http://heartscanblog.blogspot.com/2007/06/ct-scans-and-radiation-exposure.html

    You may notice some differences. There's enormous variation in exposure, depending on how it's measured, how the scan is performed, type and manufacturer of scanner. However, you can get a good idea of ballpark figures from the table in the blog post.

  • Dr. Davis

    7/19/2007 1:02:00 AM |

    Let me try that URL again:

    http://heartscanblog.blogspot.com/
    search/label/CT%20scans%20and%
    20radiation%20exposure

    Or, go to the left sidebar of Blog contents and see "CT scans and radiation"

  • JT

    7/22/2007 1:55:00 AM |

    I watch Fox news.  And with that statement I'm sure some are rolling their eyes.  Never before in the history of America has declaring what news channel one watches apparently pigeonholed one on their political views.  

    Like many I get my news from different locations: internet blogs, TV, radio, magazines, newspapers, etc, but in the morning I often watch Fox and Friends.  I do so for two reasons I suppose, the first being that I enjoy the joking around / humor on the set.  The second reason why I watch Fox is because it goes out of its way to present two sides of a debate.  It seems revolutionary what Fox has done to TV news - present two sides of a story.  Some people become terribly wound up over this.  On a personal note, I have an "ultra liberal" uncle, by his own definition, that in all honesty is so upset over Fox news and me watching it that he no longer communicates with me.  Uncle Gordon probably has never watched Fox News.  He only knows what he has heard.  And knowing him if he did watch he would only see the conservatives and not notice the liberal view point.  I hope one of these days he calms down and we can find ourselves on friendly terms again.  Change is hard for some to come to terms with.          

    When reading this blog, it disturbed me.  I wish that all news reporters tried harder to present two sides to a story. These high radiation reports would be easy to demonstrate as being only half true.  But instead, because of poorly researched, unprofessional reporting, there undoubtedly will be Americans that will decide to not have a life saving CT heart scan for fear of radiation poisoning.  And that is sad.

  • Dr. Davis

    7/22/2007 3:09:00 AM |

    Hi, JT--

    I couldn't agree more.

    If there's one theme that presents itself over and over lately, it is the struggle to discern the truth in the sea of information we're all presented with every day. I can only hope that we all zig-zag towards a real truth over time.

  • Darwin

    7/24/2007 6:34:00 PM |

    Re the CTCA - new study out concerning radiation exposure for young women.

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