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These ads encourage you to make demands of your doctor; they make you an his antagonist rather than his collaborator. That is a sure recipe for friction.
If you have symptomatic coronary artery disease, you want to be able to ask questions and expect your doctor to take the time to give you detailed answers. Yet how dare you challenge an interventional cardiologist’s judgment.
You might ask: What are the relative advantages and disadvantages of the various treatments? Should I have only medical therapy percutaneous transluminal angioplasty with stents, or coronary artery bypass grafting?
HISTORY OF STENTS
Coronary stent implantation was first performed only as a bailout procedure for poor angioplasty results. Today, it has become a primary modality of coronary revascularization.
Percutaneous coronary intervention has been around for thirty years, but in its early days balloon angioplasty was plagued by very high rates of re-narrowing of the artery, often within a month. The bare metal stent was the obvious solution, getting restenosis rates down from around 30% to about half that. Drug-coated stents were introduced in 2003, to solve the problem of restenosis; it dropped the restenosis rates down to about 4%. But that was still too high. The drug-coated stent, was found to leak immunosuppressive and anti-proliferative compounds that prevented tissue regrowth around it.
The new devices were approved following trials with limited follow-up, under an FDA deal, that after approval, patients would be further followed to detect late effects.
Neither the FDA nor the manufacturers' studies revealed any problems. Soon independent academic studies began to hint that by three years after placement, these drug-eluting stents had lost their advantages over bare metal ones and might even be linked to higher mortality. A study from Duke in 2001, found that stents, used to prop open clogged arteries, might be riskier than doctors first thought.
WHAT ARE STENTS?
Stents are tiny wire-mesh tubes used to prop open arteries after doctors clear them of blockages. Some stents have a drug coating meant to keep vessels from re-clogging following such procedures
HOW DO STENTS WORK?
The drug-coated stents now almost exclusively used, have a coating of drugs that keep the arteries from developing scar tissue. A balloon-tipped catheter is place into a blocked artery by angioplasty. When the balloon is inflated, the clot is pushed aside. There is a stent, at the tip of the catheter. It acts as a strut to keep the artery from closing again..
AFTER A HEART ATTACK
If you have a complete coronary blockage, is there any benefit, after the acute heart attack, to opening the artery anyway? If the benefit is very small, is doing the procedure worth the extra cost ?
STENTS AFTER HEART ATTACK FOLLOW UP
Medications and heart bypass offered greater protection over angioplasty and stents—both of which open arteries. Initial findings from the Occluded Artery Trial (OAT) revealed that four years after heart attacks, the death rate, incidence of heart failure, or a follow-up heart attack were not minimized by a so-called “late attempt” at removing heart blockage. The heart muscle is pretty much dead where that artery is blocked, and one is not going to help it out by opening the artery.
One year after stent implantation, patients were as unable to climb stairs as those not implanted. Also, while 477 stent patients received hospital bills about $7,000 higher than nonstent patients, their quality of life was shorter—after two years—than those patients only treated with medications.
RESTENOSIS AFTER STENTS
Bare stents resulted in 5 times more clots than the newer drug coated stents. Because of more scarring and restenosis (reclosure of the artery), it is not used much now. But the good thing was that the risk of clots disappeared in a few months.
In 2003, drug coated stents were introduced. They reduced the restenosis rate from one out of three, with the bare stents), to one out of ten with the drug coated stents. One out of 200 patients getting a drug coated stent, however, will get a blood clot within 4 ½ years (Cleveland Clinic). These clots lead to a major heart attack 70 % of the time and death 40% of the time.
This has required continuous anti-clotting medications and monitoring for all five years. After inserting a stent, you can get blood clots months or even years later.. The rate of stent thrombosis is at least 1%, and over 2000 people die each year from this.
PROBLEM WITH ANTICLOTTING DRUGS AFTER STENTS
The problem with drugs used to prevent clots, like aspirin and plavix, is that they also acts on the platelets, the sticky cells. This results in serious side effects, including bleeding.
A debate now rages over how long you should be given these antiplatelet drugs — usually thienopyridine (clopidogrel or ticlopidine) in conjunction with aspirin. The Journal Circulation carried an advisory from the American Heart Association recommending 12 months of antiplatelet therapy with all stents. The FDA has now endorsed this position in a commentary published in the NEJM.
IS REOPENING AN ARTERY A GOOD IDEA?
Without a clear increase in survival, the Canadian public health care systems still use the bare metal stents. While 80% of stents used in the US today are drug-coated, only 30% of drug coated stents are used in Canada. Bare metal stents go for about $800 in Canada, while the drug-coated stents in the U.S, cost two to four times as much. While the US does about 800,000 such procedures a year, only 35,000 are done in Canada, (about half as many per capita).
A December 2007 article in NEJM appeared to bring us full circle. In 2,166 MI patients with total occlusion of the infarct-related artery, those undergoing a stent operation, showed no benefit over those given simple medical treatment (1970s-style). The study question whether reopening the artery is even a good idea.
If you have more than one blocked artery, bypass surgery provides a lower risk of death and heart attacks than do procedures involving any type of stent, says a NEJM study.
IN 2008, 800,000 angioplasties were done, for a total cost of $10 billion. Of these, Duke University concluded that about half could have received comparable treatment via drugs, diet, and exercise, with less risk of re-clogging. (NEJM)
WARNING LABELS
A petition was filed recently with the FDA, by the Consumers Union requesting the FDA require all advertisements for implantable devices … and heart stents – carry a warning about failures of the devices once they are in the body, to require clear warnings about the dangers of infection during and following such surgery, and provide information about how long the devices are likely to last once they are in the body,. “Many of these devices can restore high quality-of-life to patients, but we are concerned that serious and possibly deadly side effects like infections are consistently understated in these device ads,” (Dec.17,2007)
CONCLUSIONS
Implanting stents is financially lucrative both to the hospital and the doctor. Many cardiologists feel if no more are implanted, 40,000 Americans are going to have thromboses in their drug-eluting stents. Twenty-six thousand will have heart attacks. Thirteen thousand will die. The benefits of doing the procedure seem to outweigh the risks.
The FDA's approval criteria for drug-coated stents was : newly diagnosed coronary lesions, less than 30 mm long, in clinically stable patients without additional serious medical conditions. It seems only 40% of patients treated with drug-coating stents meet these criteria. The rest of the patients are getting off-label surgical treatment, typically for much more serious and complicated conditions.
Angioplasty was adopted, 30 years ago, without a clear demonstration that it offered a survival benefit over drugs. Then stents were added without demonstrating they were better than balloon-only treatment. Then drug-coated stents were introduced as the state of the art treatment. This controversy has now led to fewer doctors recommending drug-coated stents and some insurance companies are reconsidering their coverage of them.
This is an almost pure example of money-driven, consumer-driven medicine, manufacturers intent on profits pushed consumers to push doctors and hospitals to use a product that they themselves were not convinced was safe. There’s a huge feeling that it isn’t adequately proven, but there’s a lot of anxiety about being left behind if they accept the evidence.
This is not how we the public want medical decisions to be made.
Visit www.drneedles.com for more information on controversial medical topics. Your comments are always appreciated.
Sources: NEJM Feb 19,2009, BMJ Mar. 2007,Occluded Artery Trial, Consumers Union, Dec. 12, 2007
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