Medicolegal Issues

Drug Stents and Surgery


 

Dr. Jaffer

Drug-eluting stents (DES) are a medical success story: In the four years since they were approved, in-stent restenosis rates have gone from the 25%-30% associated with bare-metal stents to the single digits.

Thanks to this track record, the world market for stents has doubled to $5 billion—despite the fact patients with DES must take aspirin or clopidogrel to prevent thromboses.

It’s easy to forget not all questions concerning DES have been answered, despite their wide acceptance and good overall outcomes.

One concern is discontinuation of antiplatelet therapy for DES patients who require noncardiac surgery.

In the November-December 2007 Journal of Hospital Medicine, senior author Amir Jaffer, MD, and colleagues at the Cleveland Clinic in Ohio studied the relationship between a patient’s time on antiplatelet medication and the consequences of discontinuing those agents in preparation for surgery.

Read this Research

Find this study (“Discontinuation of antiplatelet therapy prior to low-risk noncardiac surgery in patients with drug-eluting stents: a retrospective cohort study”) in the November-December 2007 Journal of Hospital Medicine.

“This is a common clinical conundrum,” says Dr. Jaffer, director of the Cleveland Clinic’s Internal Medicine Preoperative Assessment Consultation and Treatment (IMPACT) Center. “We face this question almost every day in our practice relative to perioperative care.”

Patients slated for noncardiac surgery are seen first at the IMPACT center, where hospitalists conduct the preoperative evaluation.

Data show that patients with bare-metal stents run a high risk of stent thrombosis if they undergo noncardiac surgery within two to six weeks of stent placement.

But information on DES is hard to come by, “so we decided to try to get a handle on the safety of stopping these drugs,” says Dr. Jaffer.

The authors, led by Daniel J. Brotman, MD, studied all patients who had undergone DES placement and were evaluated for noncardiac surgery at the IMPACT Center from July 2003 to July 2005. They examined 30-day rates of postoperative myocardial infarction (MI), DES thrombosis, major bleeding, and all-cause mortality—all relative to how long the patient had been on and off antiplatelet therapy.

The type of surgery each patient underwent was classified by invasiveness and anticipated blood loss, according to the system developed by L. Reuven Pasternak, MD, vice dean, Bayview Campus, Johns Hopkins University in Baltimore, and his colleagues.1

The categories range from one, which includes cystoscopy, breast biopsy, and other minor procedures that involve little if any blood loss, to five, which encompasses highly invasive procedures with anticipated blood losses in excess of 1,500 cc, such as major vascular repair.

The authors studied all patients who had undergone drug-eluting stent placement and were evaluated for noncardiac surgery at Cleveland Clinic in Ohio from July 2003 to July 2005. They examined 30-day rates of postoperative myocardial infarction, thrombosis, major bleeding, and all-cause mortality—all relative to how long the patient had been on and off antiplatelet therapy

A total of 114 patients met the study criteria. Seventy-five (66%) of the patients were men, and the median age was 71.

The most common comorbidities were diabetes (in 41% of patients), a history of coronary bypass (34%), and chronic renal insufficiency (20%). Most patients (73%) received sirolimus (Rapamune) stents; 28% received paclitaxel (Onxol) stents; and 33% had more than one DES.

Of the patients studied, 69 (61%) underwent surgery more than 180 days after receiving their DES; 30 (26%) had their procedures within 91-180 days of receiving the stent; and 15 (13%) had their operations within 90 days of stenting.

The most common procedures were major orthopedic surgeries such as hip replacement (34.2% of patients), and ophthalmologic procedures like cataract removal (26.3%).

No procedures fell into category five, and only 6.1% fell into category four; the rest were in categories one to three.

In most cases (77%), antiplatelet therapy had been discontinued a median of 10 days before surgery, with patients remaining off the drugs a median of 14 days after surgery.

There were no deaths. The most serious complications were non-ST-elevation myocardial infarction (NSTEMI) in two patients, and retroperitoneal hemorrhage following kidney transplantation in a patient who had been taking aspirin and clopidogrel until a week before surgery.

These findings suggest that “transient termination of antiplatelet agents in the perioperative setting is not associated with high morbidity and mortality in patients with DES, even when patients have had their stents implanted in the previous three to six months,” the authors write.

The study has limitations, Dr. Jaffer warns. “This was a small study, and more than 50% of our patients had surgery more than six months after DES placement,’’ he says. “It is difficult to predict a true relationship between timing of stent placement and subsequent surgery.”

Also, about a third of the patients underwent minor procedures, and roughly one-fifth never discontinued antiplatelet medication.

There were “several issues that may have led to fairly reasonable outcomes, and which could also be related to why we saw a fairly low rate of thrombosis,” he says.

In part because of these remaining questions, he recommends hospitalists take the timing of stent placement into account when evaluating patients with DES for surgery.

If it has been six months or less since the stent was implanted, the risk of thrombosis is still high, and “we can’t accurately say if it’s safe to stop antiplatelet medication,’’ he says. “I would treat those patients cautiously, as the literature suggests they may have a high risk of adverse events.”

But if the patient needs urgent surgery and more than six months have elapsed, “it may be safer to discontinue clopidogrel and continue baby aspirin, or to continue both antiplatelet medications during surgery if an urgent procedure is needed within six months of receiving the DES” he says. TH

Norra MacReady is a medical writer based in California.

Reference

  1. Pasternak LR. Preoperative assessment: guidelines and challenges. Acta Anaesthesiol Scand Suppl. 1997;111:318-320.

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