Sometimes Less is More
I saw a patient in my office this week who had received a stent from one of my partners last month. The man was highly satisfied with his experience—the procedure was tolerable, the recovery short, and the nurses were pretty (he specifically made a point of this, presumably because the post-hospitalization customer surveys don’t include what seemed to him to be the most important feedback metric)—but his wife had a different opinion. She was upset (and not about the nurses).
“Why did he get only one stent?”
The cardiac catheterization had apparently revealed the presence of at least a couple of blockages. The 99% narrowing—the one that was stented—was the clear cause of his chest tightness, and fixing this one had dramatically improved the patient’s ability to get from the couch to the refrigerator without gasping for breath and clutching his chest. Another coronary vessel tapered to 70%, the cardiologist estimated, but that artery received no stent. I pulled up the images from the procedure and saw that other minor disease was present but none that impinged on the vessel by more than 20 or 30%.
The concern from the patient’s wife is valid. Why not put a stent in the 70% vessel while you’re in there? The question implies the underlying logic that a 70% blockage, while perhaps not yet critical, will progress over time and eventually cause a heart attack: Let’s just put in a stent now and prevent future problems. This same line of reasoning applies to so many other things we deal with. Take cars, for example. If three of my tires are bald and the fourth is 70% bald, wouldn’t it make sense to replace them all? I know for a fact that my own mechanic has squeezed me for plenty of cash by successfully applying this logic to brake pads, filters, belts, etc.
Just today I read an article in the New York Times about this very topic (well, maybe not this exact topic—my mind tends to tie together lots of loose connections). For years now, it appears, some dentists have made a pretty healthy income by drilling and filling small “pre-cavities” that would not progress to full blown erosions and which, if left untreated, might even resolve on their own (the author cites “mineral-containing saliva” that possesses some sort of salutary effect—and to think I’ve lived with my spit for four decades and never realized how magically healthy it is). The concept behind a more conservative approach to cavity treatment is not without detractors, as evidenced by one dentist’s comments:
Dr. Douglas Young, a dental diagnostician at the University of the Pacific, thinks that “watchful waiting” doesn’t make sense.
“If you were to go to a physician and he were to diagnose risk factors for heart disease, the physician would take action and treat the early signs of disease and try to prevent future disease,” said Dr. Young, who helped develop a standardized cavity risk assessment adopted by the dental association.
I have a feeling from his comments that Dr. Young would join my patient’s wife in her dissatisfaction over our apparent disregard for moderate coronary obstructions. Watchful waiting, in the words of Dr. Young, is an approach that any medical professional worth his or her salt—especially those that deal with heart disease—would never deign to recommend.
But here we are—my partners and I—suggesting nothing more than watchful waiting. Why?
The answer lies in an understanding of how coronary atherosclerosis actually causes problems. Here I cite a paragraph I penned in a blog post titled “The Paradox of Stenting” from February, 2009:
Despite our fervent desires to the contrary we know that intervening on a coronary blockage in an individual with little or no symptoms does nothing to decrease the future risk of heart attack. We have numerous trials and procedure registries that attest to this. Why is this?
Heart attacks occur because a cholesterol-rich “plaque” in the wall of the artery becomes unstable, ruptures, and the body tries to seal the damage with proteins and cells that form a clot. The clot occludes the flow in the vessel and all downstream muscle is starved for oxygen. We’ve known for several years that the physical dimensions of a stenosis (ie. how narrow the blockage) don’t determine its risk of plaque rupture and complete vessel closure—a 50% blockage may be just as likely to result in a heart attack as a 90% blockage.
My patient had symptoms of coronary narrowing—chest tightness with exertion—that resolved completely once the 99% blockage was fixed. The remaining cholesterol plaque in the range of 20-70% resulted in no adverse symptoms. If a 70% blockage never worsens over time, it’ll never cause problems.
It is well established that drilling through an otherwise stable obstruction provides no benefit to quality or length of life, although this wasn’t always known. When catheter-based coronary plumbing was first developed the early operators gleefully attacked every blockage in the belief that they were saving the patient from heart attack and death. The so-called “oculostenotic reflex” led stent specialists to engage in aggressive vascular arts-and-crafts that produced gorgeous appearing vessels on the video monitor, but did little to make the patient healthier.
Thankfully, we’ve learned from our mistakes. Opening blocked vessels is useful in really only two general areas:
- Heart attack, where the rule of thumb is to open the tightest blockage (we refer to it as the “infarct-related artery”) and leave the rest as is.
- Symptomatic blockages such as the 99% plug that caused my patient his troubles. If, on the other hand, a person has no chest pain or breathing difficulty associated with the disease, we provide no benefit by uncorking it—even if the blockage is 100%.
Does that mean we do nothing? Of course not. On the contrary we eagerly provide the really meaningful therapy in the battle against coronary disease: medications and lifestyle modification. Sure, it’s not particularly sexy—not like thousand-dollar stents in high-tech cath labs, at least. But it’s effective. As I pointed out in another post, the really meaningful impact on a person’s risk of future heart attack and stroke comes in the form of diet, exercise, smoking cessation, and the right prescriptions.
As for my patient and his wife, they left my office with that skeptical look on their faces you get when someone tells you something that you’re sure is untrue. I had done my best to walk them through the logic behind our conservative approach but it wouldn’t surprise me if she immediately hit the Yellow Pages when she got home, looking for another cardiologist who isn’t so incompetent. I don’t know who I’d recommend for a second opinion in the matter—most cardiologists recognize the limitations of performing unneeded procedures—but I sure know a dentist who’ll gladly take her side in the argument.
Thanks Dr. V - this is one of the best responses to a very commonly-asked question that I've seen yet. In survivor forums, support groups, cardiac rehab, my own blog, and in the audiences at the women's heart health presentations I do, it is very clear to me that doctors are NOT doing a good job in explaining the "why" behind the "what" question. Add to this the recent media interest in all those "stent-happy" cardiologists now facing legal/disciplinary charges, and patients are either confused that they may have had an unnecessary stent implanted, or that they may have missed out on a stent they should have had. Q: please tell me why aren't ALL doctors taking a page from your book and spelling this dilemma out as clearly as you have done?
Thank you for this information. I was surfing the web and this was one of the most informative sessions. Nice job.
Dr. Van De Graaff
Joel and Jena, Good questions. Joel, we face this dilemma all the time. We see a blockage and wonder what sort of functional significance it has. Conventional wisdom has it that a stenosis has to get to about 70% before it begins to hinder flow when the heart is a peak oxygen demand (sprinting up a hill, say). We handle this in a couple of different ways. We can simply observe the patient, with the idea that we'll fix if they have symptoms (exertional chest pain being most common). Alternatively, we have the patient do some type of functional study, such as a treadmill nuclear myocardial perfusion scan (nuclear stress test). This test allows us to determine how much of the heart muscle is actually suffering from oxygen deprivation. If the scan looks good then we leave the blockage alone. Jena, I don't personally believe that coronary obstruction can be cleared up by clean living and medications (admittedly, though, there are some small studies that suggest regression of the blockage on statin therapy--Crestor, Lipitor, etc.). That's not to say lifestyle and medication compliance doesn't have a positive effect. Such therapies will promote what we call "plaque stabilization," meaning thickening of the fibrous cap and depletion of the more atherogenic lipid particles in the plaque's core. The end-effect is a dramatic reduction in the risk of plaque rupture and subsequent heart attack. Thanks to both of you for your insightful questions. Dr. VDG
What are the chances of clearing a 70% blocked artery by meds, diet, and exercise? If the chances are good, then this couple is crazy to consider doing an invasive procedure when it isn't necessary and there are other options to fix the problem. And Joel is sounding more and more like a doctor every day...go figure.
It's too bad there's not a pamphlet stating this. I had this same question when my husband's grandmother had a heart attack earlier this year. We have had to come to the acceptance that the doctor knew best, but it always has been stuck in the back of our minds. Thank you for giving us the peace of mind we were searching for.
How do you know beforehand that the 70% blockage wasn't causing symptoms? Clearly the 99% blockage was causing symptoms but what if that was masking the symptoms he would have from the 70% blockage and then after stent placement he would continue having symptoms? Is there a limit that certain blockages won't cause symptoms, or does it depend on the person and the artery?