The New England Journal of Medicine just published a study that followed the course of nearly four hundred thousand patients at 663 American hospitals who were referred for elective diagnostic coronary angiography.  The typical patient in this mix was someone with risk factors for coronary disease who had undergone a stress test suggestive of possible blockage.  None of the patients had a diagnosis of prior heart attack or coronary artery disease.

In this group, 38% were found to have significant coronary blockage (a narrowing that’s worth fixing by angioplasty/stenting or bypass surgery) and 23% had blockage that was not severe enough to cause obstruction to flow.  The remainder (39%) had absolutely clean coronary arteries.

The general verdict among medical pundits is that we are performing too many coronary angiograms and that the testing we do to determine need for angiography (i.e. stress testing) is inadequate to allow us to screen for those patients most in need of this procedure.  After all, if only 38% of patients actually need to have something fixed, then 62% were exposed to the risk of the procedure with no apparent benefit.  What follows are higher medical expenses, unnecessary risks and avoidable emotional stress to the patient.

The publication isn’t so much a blemish on the coronary angiogram as it is on our ability to determine who should actually get sent for a cath.  Normally, a patient with some type of chest discomfort and risk factors for coronary disease will see a cardiologist and subsequently undergo some type of stress study to determine if there is impairment to blood flow in any region of the heart muscle.

I have previously bored my readers with a lengthy diatribe about the uses and limitations of stress testing and I’d encourage you to read it again if you’re suffering any form of insomnia.  The bottom line is that the science of screening for coronary disease is very inexact.  At this point, and for the foreseeable future, there is no test that will easily differentiate chest pain that arises from a coronary blockage from chest pain of noncardiac provenance.  As a cardiologist, the best I can do is listen intently to the description of the symptoms, assess the patient in his or her entirety (risks, genetics, bad habits), and rely on stress testing that at times seems only slightly better than flipping a coin.

As an aside, the world of medical screening has had its share of black eyes recently.  Take testing for prostate cancer, for example.  Just last year the New England Journal of Medicine published a comparison of the two main screening tests for prostate cancer and the ability of each to cut the risk of death from this common malignancy.  The high-tech laboratory assay prostate specific antigen (PSA) and the decidedly low-tech digital rectal exam both did an equally poor job of lowering the death rate from cancer among asymptomatic men.  This is bad news for any primary care doctor who, like me, feels that running the tip of their finger over the top of your prostate is actually a useful mechanism for determining the presence or absence of cancerous cells lurking inside this well-buried gland. 

A very interesting opinion, authored by Dr. Richard Ablin, the inventor of the PSA assay, appeared in the New York Times last weekend and criticized the fact that we in the medical community have embraced the generalized use of PSA as a screening test:

“I never dreamed that my discovery four decades ago would lead to such a profit-driven public health disaster. The medical community must confront reality and stop the inappropriate use of P.S.A. screening. Doing so would save billions of dollars and rescue millions of men from unnecessary, debilitating treatments.”

Now back to the subject of coronary angiograms: I take some exception to the idea that we are burdening the population with unnecessary trips to the cardiac cath lab and I think we can view the results of this recent study through a slightly different lens.

In this population, 61% of patients were given the firm diagnosis of coronary artery disease (the 38% with high-grade blockage and the 23% with less severe narrowing) and I would argue that the coronary angiogram—despite the fact that it is an invasive test with possibly serious risks—served these patients well.  Faced with the understanding that their blood vessels are prone to cholesterol build-up and narrowing, these patients will be treated more aggressively for blood pressure and lipid control, will have additional incentive to give up smoking and start exercising, and may pay more attention to diet.  Ultimately, I have to believe that this group of individuals will suffer fewer heart attacks and strokes as a result of risk factor modification.

I would argue that even those patients with normal arteries received some benefit, provided they didn’t suffer any complication of the procedure.  By having the “gold standard” test, they learned that the symptoms they are suffering are not related to the heart and are thus not something that could potentially lead to life-threatening complications.  There’s a certain value to the peace of mind that this knowledge provides. Unfortunately, there’s no way to factor this ephemeral reward into research studies such as these.

I agree that we need better testing—better testing that is inexpensive, low-risk and noninvasive—but this will not be coming any time soon.  Until then we as doctors will keep doing our best and ask for understanding from those patients we send on an unnecessary tour of the cath lab.

As you probably already know, former president Bill Clinton recently underwent a “heart procedure” upon his return from a visit to Haiti that the press later clarified as angioplasty and placement of a stent.  Mr. Clinton used to have quite a reputation as a man who never met a greasy hamburger he didn’t like and was rewarded for his habits with coronary bypass surgery in 2004.  Nowadays, things are a little different around the Clinton household—from what I can tell he has given himself over to a healthier, more ascetic lifestyle with more time spent on the treadmill than at the drive-through. 

After the procedure the ex-president (and current UN envoy to Haiti) had nothing but praise for his doctors, but reserved his most flattering comments for the technology itself:

"It's miraculous with the stents," Clinton told reporters, referring to the devices used to clear a clogged artery during the operation Thursday.

Clinton, 63, was speaking publicly for the first time since entering the New York Presbyterian Hospital. He was released earlier Friday.

"I didn't (take) any sedatives or anything, so I was alert. I wanted to watch it. I got to watch it on the monitor," he said.

Since catching wind of this story I have tried desperately to find a way to spin this into a clever yet respectful blog topic that would both entertain and inspire my readers.  Something bold, something different—more than just a recitation about the merits of coronary stenting.  Instead of my usual tired commentary I wanted to find a truly inspired angle.

But then I thought, why break with tradition?  So, here you have it—everything you ever wanted to know about coronary stenting but never learned in junior high health class.

First off, a little nomenclature (that I’ve found is frequently misunderstood among non-medical people):

Angiogram (synonyms: heart catheterization, cardiac catheterization, cath) is where we run a small tube (catheter) through the artery to inject dye into the coronary arteries to take pictures.  With this procedure we don’t fix anything.  It’s more or less just a fancy x-ray with dye in the arteries.  That’s the difference between this and . . .

Angioplasty (synonyms: balloon angioplasty, PTCA), where we actually expand a balloon inside a blocked vessel to open a passageway for blood to get down the clogged artery.  Up until about 15 years ago, before the widespread use of reliable stents, most patients had angioplasty alone.  The problem with angioplasty alone, though, was that the vessel frequently closed up again within 6 months and the patient had to return to get the whole thing done again.  While this was good for the cardiologist wanting to make payments on his second home in Aspen, it wasn’t so good for patients.

Angioplasty with stenting is the most common approach today and this is what I’ll explain now.

Have you ever taken apart a ball point pen that has one of those little tiny spring thingies in it?  Now picture the spring, but very small, looking more like chicken wire and made of really, really expensive metal.  Good.  Now that you have that image in your mind click on this hyperlink to see if I did a reasonable job of explaining the appearance of a coronary stent.

To place a stent, the interventional cardiologist first performs angiography to take a picture of the blocked vessel so that he or she can make an estimate of how best to fix the vessel (please click here to see how not to do this).  At this point the operator will thread a very small and flexible wire into the coronary artery and snake it through the narrow center of the blockage.  He* then advances the wire as far out into the vessel as possible. 

Using the wire as a rail the doctor slides a small catheter equipped with an inflatable balloon out to the point of the blockage.  The balloon expands and all the cholesterol and platelet gunk simply gets squished outward into the wall of the vessel (click here for a nice picture or here for brief video).  He will then repeat the process, but this time with a balloon that is wrapped with a non-expanded stent.  The balloon inflates and the stent expands.  The doctor deflates and removes the balloon and the stent stays in place.  If he’s satisfied with the final result he’ll remove the wire and catheter and the patient is returned to the recovery room.  The whole process generally takes less than 45 minutes.

When I first started out in cardiology I was a little surprised to learn that we don’t really clean out the cholesterol build-up from inside the artery when we fix it.  This is not the roto-rooter job you get from a plumber when your pipes are clogged.  All we do is use the stent to compress the unwanted plaque into the vessel wall and pin it out of the way with the stent.

The process of expanding a balloon is actually quite traumatic to the vessel wall (on a microscopic scale) and triggers a cascade of cellular reactions that makes the body want to heal the vessel with something akin to a scab.  That sort of response is good for a scraped knee, but not so desirable inside a vessel that measures only a few millimeters and provides flow to what is arguably one of the more important organs of the body.  A combination of the metal stent (to prop open the vessel) and the use of anti-clottting drugs such as aspirin and clopidogrel (Plavix) allows the vessel heal without unnecessary narrowing to the artery.

If done right the chance of a modern stent closing down is very, very low.  In my experience a patient with a previous stent is more likely to develop a new blockage elsewhere in the circulation than inside the stent.  Patients also recover very quickly from this procedure.

An article from February 13 reported on Mr. Clinton’s quick recovery and eagerness to get back to full activity.

"I feel great. ... I even did a couple miles on the treadmill today," Clinton said, speaking to reporters in a leather jacket from the driveway outside his home. He said doctors advised him "not to jog but walk. Not to walk fast up steep hills for a week."

While some commentators have suggested that Clinton needs to tame his active schedule I think is the wrong approach.  If I were his doctor—knowing what I do about the success of modern stents—I’d encourage him to get back into life at full speed (especially on the treadmill).  Since he’s become the go-to guy for massive natural disasters I don’t think we can afford to have him sidelined for long.

*Sexism alert:  Please note how I’ve switched from the more correct “he or she” to the less verbose “he” when I refer to the cardiologist.  I don’t mean to denigrate the other half by eliminating the “she,” but since only 17% of cardiologists in this country are women, and of those only 10% specialize in stent placement, I’m probably statistically on safe ground in adopting the masculine pronoun to describe my hypothetical interventionalist.

There’s an iconic image from legendary medical illustrator Frank Netter, M.D. that I will never forget from my medical school days. It’s a picture of a man clutching his chest as he exits a restaurant to trudge into the snowy night. The artwork was originally published in 1969 as part of the CIBA Collection of Medical Illustrations that serves as the benchmark for anatomic art in the last half century. I’d venture that there is not a doctor on the planet who is not familiar with the artistic footprint of Dr. Netter.

This particular picture accompanies the section of the atlas pertaining to “angina pectoris,” the chest pain that arises when the heart muscle is not getting an adequate supply of blood and oxygen. While the symptoms can be variable, angina is most often described as a squeezing pressure in the chest. As is typical of Dr. Netter’s style, his illustration captures many of the subtleties of the subject described. The man is middle-aged and mildly overweight and one can clearly see the burning ember of a cigarette butt he’s dropped into the snow. He is coming out of a restaurant and lumbering up a couple of steps into the driving winter wind. His right hand claws at his chest (see Levine sign) as his left hand loses its grip on his brief case.

In this illustration, Dr. Netter has made sure all the elements are there for a classic case of angina.

Risk factors? Check.

Exertion? Check.

Recent culinary indiscretion at a local pub? Check.

Driving snow and winter wind? Now it’s getting personal.

Those of us in the Midwest have had our share of arctic conditions over the last month as our temperatures hover well below freezing for what seems like an eternity and snow blankets our region to a degree that’s not been seen in years. The deep drifts have brought with them the familiar early morning buzz of snow blowers being reluctantly fired up for action, and, with that, come the admissions to the hospital of patients with heart attacks and chest pain.

While this is something I can’t quantify with any reliable objective data, my feeling is that I have seen more patients this year with heart conditions exacerbated by the elements than I’ve seen in years past. Is this just my imagination—my mind, being driven mad by the numbness of the arctic chill—or is there evidence linking a miserable winter to a rise in heart disease?

Indeed, solid research confirms the link between a bad winter and a rise in the rate of cardiac events. In one study, published in the British Journal of Medicine in 2004, researchers tracked temperature and climate data from 24 different countries in an attempt to establish a link between lousy weather and heart attacks. They discovered that a strong relationship exists between low temperature and the population’s rate of heart attacks and stroke. Their conclusions were so robust that they were able to provide an algorithm for determining what sort of rise in problems we can expect with cold air: “On average, a 5°C reduction in mean air temperature was associated with a 7% and 12% increase in the expected hospitalization rates of stroke and AMI (heart attack), respectively.” (How would it be if we added that to our evening weather broadcast? “And for tomorrow we can expect a high of 5 degrees, winds out of the north at 15 mph, and scattered heart attacks throughout the metro area.”)

Another study, published in the journal Circulation the same year, showed that the risk of cardiac-related death is at its absolute highest in the period between Christmas and New Years Day. The authors are careful to point out that it’s not clear whether the increased prevalence of heart attacks is due to the cold weather or the abundance of stale fruitcakes and spiked eggnog.

What, exactly, are the possible factors that lead to winter heart attacks in susceptible individuals? Here are some possibilities:

1. The body shunts more blood to the skin when the air is cold to maintain body temperature. To do this the heart needs to work harder to cycle the blood volume more quickly.
2. Depression, long linked to the cold darkness of winter, is known to be a risk factor for cardiovascular disease.
3. Flu and cold viruses can trigger inflammatory responses in the coronary arteries that can disrupt the delicate balance of coronary cholesterol plaques.
4. People generally exercise less when the weather is bad and slip into worse physical condition. Just this week Circulation published a study linking risk of cardiac death to the number of hours a person sits glued to American Idol.
5. People tend to eat more, smoke more, and gain more weight during the holiday season.

At the precise moment a person with occult coronary disease is at his deconditioned, flabbiest worst, he decides it’s time to man up and get out in the subzero temperature to perform his own stress test behind a 75-lb snow blower. It’s no surprise the night ends up with a trip to the cath lab.

I suppose the best way to avoid a January visit to the coronary care unit is to keep yourself in good shape during the rest of the year so that snow removal season isn’t such an extraordinary departure from your usual physical activity. Stay warm, get your flu shots, and watch your diet and your weight.

If there’s any question about your physical capability to shovel snow or rake ice off your roof, check with your doctor—it may be better to first try the conventional office-based stress test before you attempt the do-it-yourself-in-the-driveway method. I don’t think Dr. Netter needs any more modeling subjects for his medical atlases.