Noncardiac Surgery Safe Six Months After DES

October 07, 2013

BIRMINGHAM, AL — For patients undergoing noncardiac surgery within two years of receiving a coronary stent, only those undergoing emergency surgery and those with advanced heart disease were at an increased risk of major adverse cardiovascular events (MACE), according to the results of a new study[1].

In contrast, those who had a stent implanted at least six months before undergoing noncardiac surgery were not at an increased risk of MACE, nor did the type of stent used influence the risk of adverse events, report investigators.

"The main thing we found is that surgery happened very often in that first year after a coronary stent," said lead investigator Dr Mary Hawn (University of Alabama, Birmingham). "Whether it was a bare-metal stent or a drug-eluting stent [DES], the rate of adverse events wasn't different by the type of stent implanted, either overall or by when the stent was implanted. The guidelines would suggest that six weeks after a bare-metal stent, the risk goes down, and after one year for a drug-eluting stent the risk goes down, but we found that both stents were associated with a high risk early on, and by about six months the risk seemed to hit baseline."

The study, a large, national, retrospective analysis of nearly 42 000 patients, is published online October 7, 2013 in the Journal of the American Medical Association.

Wait One Year Before Surgery After Receiving DES

Speaking with heartwire , Hawn said the potential risk of MACE among stented patients undergoing surgery within the first year after stent implantation has been an issue among cardiologists and surgeons and was thought to be related to stopping dual antiplatelet therapy. In 2007, the clinical guidelines were revised to recommend that patients who receive a DES continue with dual antiplatelet therapy for at least one year and that surgery should be delayed, if at all possible, within this first year. If surgery couldn't be delayed, then it should continue without the patient stopping dual antiplatelet therapy.

"However, this is really based on limited data, including case reports, and there really hasn't been a large or national study looking at the true rate of cardiovascular events," said Hawn. "So we undertook this study to get a better estimate of the real risk, when the risk was the highest, and what other factors contributed to that risk."

The researchers conducted a retrospective cohort analysis of 41 989 patients in the Veterans Affairs (VA) and Centers for Medicare and Medicaid Services (CMS) systems undergoing noncardiac surgery within two years of receiving a stent.

Between 2000 and 2010, there were 124 844 stents implanted and of these treated patients, 22.5% underwent noncardiac surgery within the first two years. For the 28 029 patients who underwent surgery, there were 41 989 surgeries performed. Within the first 30 days after surgery, there were 1170 nonfatal MIs or nonfatal coronary revascularizations, 141 fatal MIs or fatal coronary revascularizations, and 669 deaths.

For those who had surgery within the first six weeks of stent implantation, the MACE rate was 11.6%. For those who had surgery from six weeks to less than six months after receiving the stent, the MACE rate was 6.4%. Between six months and less than one year and between one and two years, the MACE rates were 4.2% and 3.5%, respectively. The risk of MACE was also significantly higher among patients treated with a bare-metal stent vs those treated with a DES (5.1% vs 4.3%, p<0.001).

However, in a multivariate, risk-adjusted model, only admission for emergency surgery, a history of MI in the six months preceding surgery, and a revised cardiac index >2 were significantly associated with an increased risk of MACE.

After six months, Hawn said it didn't matter what type of stent was implanted. Instead, the patient's risk, their MI history, and whether or not they were undergoing an emergent procedure were more important variables. For surgeons, when assessing whether or not it is safe to operate on a patient who has received a coronary stent, the timing of when they received the stent isn't as important as these other factors.

"Our paper is obviously limited in that patients weren't randomized by the type of stent, so there is some decision-making in terms of the type of stent going in," Hawn told heartwire . "Still, the risk with a bare-metal stent remains elevated longer than just in the first six weeks. We need to keep that in the back of our mind. For patients who've been revascularized, if they've had a recent MI, they're going to be at a higher risk for longer than six weeks."

And for those with a bare-metal stent, the results suggest that operating within the first year can be safe, said Hawn.

Surgery After Six Months Appears Safe

In an editorial[2], Drs Emmanouil Brilakis and Subhash Banerjee (University of Texas Southwestern Medical Center, Dallas) say patients with coronary stents should undergo surgery at clinical centers with PCI capability, because this would allow prompt treatment if perioperative thrombosis occurs. They add that for patients with a bare-metal stent undergoing noncardiac surgery, the current clinical approach should not change and that surgery is generally considered safe if performed after six weeks.

"For patients with DES, surgery performed at least six months after DES implantation appears to carry low risk for stent thrombosis, especially with contemporary, second-generation DES, which have more biocompatible, durable polymer coatings. Hence, nonurgent operations should be postponed until six months after stent implantation," write the editorialists.

If surgery can't be postponed, at least one antiplatelet agent, typically aspirin, should continue to be administered, although dual antiplatelet therapy should be used if the risk of bleeding is low, they add. For patients undergoing spine or intracranial surgery where no antiplatelet can be used, surgeons should consider bridging therapy with a short-acting antiplatelet agent, such as a glycoprotein IIb/IIIa inhibitor or cangrelor (the Medicines Company).

Hawn reports no conflicts of interest. Disclosures for the coauthors are listed in the paper. Brilakis reports consulting/speaker honoraria from St Jude Medical, Terumo, Janssen, Sanofi, Asahi, Abbott Vascular, and Boston Scientific; research support from Guerbet; and that his spouse is an employee of Medtronic. Banerjee reported having received research grants from Gilead and the Medicines Company; consultant/speaker honoraria from Covidien and Medtronic; ownership in MDCARE Global (via his spouse); and intellectual property in HygeiaTel.

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