Making sense of stents

Hospitalists are sorting through new evidence that patients who get drug-eluting stents are at risk for potentially deadly stent thrombosis for months, even years, after the devices are implanted. That's added new layers to medical and surgical decision making and put more pressure on hospitalists to facilitate communication among doctors and patients.

Raymond Gibbons, MD, a cardiologist at the Mayo Clinic in Rochester, Minn., had a patient who was hospitalized with severe chest pain at rest and found to have a blockage in one artery. The man's medical history showed that he had previously undergone abdominal surgery and had since experienced abdominal pain. A recent CT indicated a possible abscess.

Should the patient get a stent to relieve his cardiac symptoms? Or should he be treated with medical therapy, at least until his abdominal problem was resolved?

Dr. Gibbons decided against the stent.

“This man could need abdominal surgery in the near future for an abscess, and that is much more pressing than his single-vessel coronary disease,” said Dr. Gibbons, who is president of the American Heart Association (AHA).

Ingrowth of tissue may cause bare-metal stents to become obstructed resulting in the need for a second procedure Drug-eluting stents inhibit this process but uncovered struts may be prone to thromb
Ingrowth of tissue may cause bare-metal stents to become obstructed, resulting in the need for a second procedure. Drug-eluting stents inhibit this process, but uncovered struts may be prone to thrombosis after discontinuation of antiplatelet therapy. The New England Journal of Medicine© 2007.

Doctors at hospitals around the country are sorting through similar scenarios amid new concerns that patients who get drug-eluting stents are at risk for potentially deadly stent thrombosis for months and even years after the devices are implanted. A new scientific advisory—drawn up by the AHA, the American College of Cardiology (ACC) and other professional groups—emphasizes the need for patients with drug-coated stents to remain on dual antiplatelet therapy and avoid elective surgery for a year because of the risk that comes with stopping the daily regimen of aspirin and clopidogrel for an operation.

While the risk of clotting associated with drug-coated stents is small, it's a life-threatening complication. “If someone has stent thrombosis, it's not just a mild heart attack. There's a high mortality,” Dr. Gibbons said.

That concern is adding new layers to medical and surgical evaluations and decision making. Should a patient with a recently implanted drug-coated stent have a hip replacement? Should a patient who will probably need a hip replacement down the road be given a stent? If surgery is unavoidable—for example, if a broken hip needs to be repaired—then what's the best way to manage the patient before, during and after the operation?

“We need to be thinking of the whole patient, not just the heart or not just the non-cardiac surgery,” Dr. Gibbons said. “There needs to be more thinking and more coordinated decision making given our current state of knowledge on stents.”

The story so far

About 1 million patients annually in the U.S. get stents, most often drug-eluting stents instead of the older bare-metal ones. Because clotting is most likely to happen in the first months after stents are implanted, patients used to be instructed to take aspirin and clopidogrel for three or six months, depending on which brand of drug-coated stent they got. Patients who get bare-metal stents are normally instructed to take the anti-clotting drugs for at least one month.

Concern over the possibility of delayed thrombosis began to grow in 2006 when longer-term data on drug-eluting stents were presented in March at the ACC's annual meeting and in September at the World Congress of Cardiology meeting. The data suggested a small but significant increase in the rate of death and myocardial infarction in patients followed for one and a half to three years after stent implantation, according to an FDA statement issued after the second meeting. In December 2006, an FDA panel held a two-day meeting to review the latest information, but the session did not settle the debate.

According to an FDA summary, the panel concluded that there did appear to be an increased risk of late thrombosis associated with drug-eluting stents compared with bare-metal stents, but the panel said that analyses presented by two stent manufacturers did not suggest an increased risk of death or MI. The panel said the magnitude of the late thrombosis problem is not clear, although the risk is higher with off-label use of the devices. Drug-coated stents are approved for discrete, newly diagnosed coronary lesions in clinically stable patients who have no other serious medical conditions, but they are often used in more complex cases.

The panel agreed with recommendations that patients who are at low risk of bleeding be kept on dual antiplatelet therapy for at least 12 months. To help clarify questions that are still unresolved, the panel said that future stent studies needed to be larger and longer and include stent thrombosis as an end point, according to the summary.

“Although the absolute risk appears to be less than 2% throughout the first three years after implantation when stents are used for the approved indications, thrombosis with drug-eluting stents is a clinically important problem that may occur long after implantation,” FDA officials wrote in a perspective piece published in the March 8, 2007 New England Journal of Medicine. “It is uncertain whether cases of late stent thrombosis will continue to accrue with longer-term follow-up.”

The scientific advisory issued by the AHA and ACC—along with the Society for Cardiovascular Angiography and Interventions, the American College of Surgeons and the American Dental Association, with input from ACP—underscored that stent thrombosis is often a catastrophic event. “In a pooled analysis of six trials and registries from the 1990s, the incidence of death or MI associated with angiographically documented stent thrombosis was found to be 64.4%,” the advisory said. It also pointed to one large study that found that clotting occurred in 29% of patients who stopped their antiplatelet therapy prematurely.

Stents and hospital medicine

The uproar over stents may have varied effects on hospitalists' practice, especially in the area of perioperative medicine.

“The hospitalist plays the role of being a vigilant advocate for the patient,” said Donald E. Casey, Jr., FACP, who represented the College on the committee of professional groups that drafted the scientific advisory on stents.

For patients with existing stents who are considering surgery, hospitalists may need to facilitate the flow of information between the cardiologist and surgeon, seeing that all needed consultations get done and that, for example, a patient's antiplatelet therapy is not inadvertently stopped without consensus. Hospitalists should also ensure that a full and detailed medical history is obtained from a patient with an existing stent, including what kind it is and when and in what location it was implanted.

Hospitalists play a key role in patient education as well.

“The hospitalist can be very influential in making sure that patients and their families understand the importance of not discontinuing their medications,” said Dr. Casey, who is vice president for quality and chief medical officer for Atlantic Health in Morristown, N.J.

Andrew D. Auerbach, ACP Member, a hospitalist at the University of California, San Francisco, said questions involving drug-coated stents are coming up more and more in his work managing patients who are scheduled for surgery.

“We have this conundrum: We have a patient with a stent in place and we want to keep them on aspirin and [clopidogrel] during surgery. How do you manage that during hospitalization?” Dr. Auerbach said. “It used to be we'd say, ‘If you had a stent in place more than six months, stop the aspirin and [clopidogrel] and go ahead and get your hip replaced.’ But that's feeling less and less comfortable.”

Stents and surgery

There is no agreed-upon protocol for how to manage surgical patients with recently implanted drug-coated stents, and practices vary from doctor to doctor and from hospital to hospital. Because patients with bare-metal stents aren't on anti-clotting drugs for long, the surgery issue doesn't come up as often.

Most cardiologists would prefer that patients with stents remain on both aspirin and clopidogrel, but that idea usually doesn't go over well with surgeons. “They're more worried about bleeding,” Dr. Auerbach said. “And it's ultimately the surgeon's call.”

The surgeon may be willing to keep patients on aspirin, and the goal then becomes limiting the time off clopidogrel.

Daniel M. Kolansky, FACP, an interventional cardiologist who directs the cardiac care unit at the Hospital of the University of Pennsylvania in Philadelphia, said patients who have a recent drug-coated stent (implanted less than a year ago) typically are told to stop clopidogrel five days before surgery, and, ideally, resume the medication 12 to 24 hours afterward. Dr. Kolansky said vascular surgeons tend to be more willing to accept some bleeding during surgery, and may agree to keep the clopidogrel going. But he said other surgical specialists, including orthopedic surgeons and general surgeons, also need to consider why it may be beneficial to “loosen their requirements and be more flexible” about keeping patients on anti-clotting drugs.

“We are navigating this issue … and we're learning more about it every day,” he said.

According to Dr. Kolansky, in an ideal situation, the interventional cardiologist knows ahead of time that a patient may need surgery and the decision can then be made to use a bare-metal stent, which requires a short regimen of anti-clotting drugs. But many surgeries are unanticipated.

Some cardiologists opt to admit patients with recent stents before surgery to administer shorter-acting anti-clotting agents. Sanjay Kaul, MD, director of the Vascular Physiology and Thrombosis Research Laboratory at Cedars-Sinai Medical Center in Los Angeles, has his patients stop clopidogrel four to five days before surgery. He then admits them two days ahead of surgery to administer intravenous doses of a short-acting glycoprotein IIb/IIIa inhibitor as a bridge between when the clopidogrel is stopped and resumed. Dr. Kaul said this approach is based on his best clinical judgment, though the scientific advisory from the AHA and other groups said there is no evidence that “bridging” agents do any good.

Dr. Kaul said the whole issue of clotting would not loom large if doctors and patients had not been so gung ho about stents in the first place.

“The root cause of the problem is our enthusiastic use of stenting for chronic stable angina,” Dr. Kaul said. “There's never been any evidence to suggest that stenting is superior to medical therapy, optimal aggressive medical therapy, in prolonging survival or reducing heart attacks.”

New research raises more questions

A recent report in the New England Journal of Medicine seems to drive this point home. The COURAGE study, published in March to coincide with the ACC's annual conference in New Orleans (see sidebar and related story),[Insert links to sidebar 1 below and story 2] found that stents offered no real benefit over medical therapy for patients with stable coronary disease.

The authors examined 2,287 people with stable coronary disease and found that while patients who got angioplasty and stents (most got bare-metal stents because coated ones were not yet in use) had some initial relief from symptoms of angina, they did not have fewer heart attacks or live longer than patients treated with medication.

The study concluded that percutaneous coronary intervention “can be safely deferred in patients with stable coronary artery disease, even in those with extensive, multivessel involvement and inducible ischemia, provided that intensive, multifaceted medical therapy is instituted and maintained.”

Yet another study presented at ACC ‘07 implied that real-world use of the CYPHER stent is safer than was shown in clinical trials. According to the MATRIX Registry, which is sponsored by Cordis, CYPHER's manufacturer, rates of stent thrombosis at one year were lower than clinical trials reported. Most patients in the MATRIX Registry, up to 80%, have chronic conditions such as diabetes that would have disqualified them from clinical trials, and therefore received stents off-label. MATRIX investigators also found that many patients had trouble maintaining the clopidogrel regimen and that one-third were no longer taking the drug as recommended at one year.

Older therapies back in fashion

There are indications that clotting worries are bringing bare-metal stents back into fashion, and even reviving interest in coronary artery bypass surgery.

Kim Eagle, FACP, chief of clinical cardiology at the University of Michigan in Ann Arbor, Mich., said that since the heightened concerns over clotting surfaced last year, the use of drug-eluting stents at his hospital has decreased from about 79% of all stenting cases to about 60%.

“We're probably moving back to a more balanced approach, taking each individual patient's profile into account,” Dr. Eagle said.

Doctors are hoping the next generation of stents under development will reduce the clotting problem. The new versions include stents coated with different and perhaps better drugs, and biodegradable stents.

In the meantime, David L. Fischman, ACP Member, co-director of the cardiac catheterization laboratory at Thomas Jefferson University Hospital in Philadelphia, predicts a “back to the future” movement as doctors rediscover the virtues of bare-metal stents.

His group will present an abstract by that title at an upcoming meeting of the Society for Cardiac Angiography and Interventions. Dr. Fischman and his colleagues studied patients with bare-metal stents who received four weeks of clopidogrel and then underwent non-cardiac surgery shortly afterward. Stent thrombosis was not a problem, Dr. Fischman said.

According to Dr. Fischman, doctors need to take time to discuss with patients the pros and cons of whichever approach is being considered: bare stent, coated stent or medical management.

“It's all about communication,” Dr. Fischman said. “It's about talking to the patient and getting all the information up front.”