Study Suggests Shortening Delay to Noncardiac Surgery After PCI

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Challenging current guidelines, new observational data suggest that the earliest optimal time for elective surgery after percutaneous coronary intervention (PCI) is 46 to 180 days after bare-metal stent (BMS) implantation or more than 180 days after drug-eluting stent (DES) implantation. The findings were published online August 14, 2012, ahead of print in Circulation.

The most recent update of the American College of Cardiology/American Heart Association guidelines, published in November 2009, suggests waiting 30 to 45 days for elective surgery after BMS and at least 1 year after DES to avoid the increased risk of stent thrombosis and other adverse events that result from surgical stress response or disruption of antiplatelet medications.

Duminda N. Wijeysundera, MD, PhD, of St. Michael’s Hospital and the Institute for Clinical Evaluative Sciences (Toronto, Canada), and colleagues linked registry data and administrative databases to identify 8,116 patients who underwent major elective noncardiac surgery in Ontario, Canada, between April 2003 and March 2009 and received stents within 10 years prior to surgery. Outcomes for stented patients were compared with those of 341,350 surgical patients who had not undergone coronary revascularization.

New Timetables Established

Approximately 34% of patients underwent surgery within 2 years after stenting, and of those, 33% received DES. For the entire cohort of stented patients, the 30-day rate of MACE (composite of mortality, readmission for ACS, or repeat revascularization), the primary endpoint, was 2.1%, while at 1 year the incidence was 9.8%.

The risk of cardiac events varied with the type of stent implanted and the time between implantation and surgery. When the interval was less than 45 days, 30-day event rates were high for both BMS (6.7%) and DES (20.0%). However, the event rates were deemed comparable to those of intermediate-risk nonrevascularized patients when the interval was at least 45 days for BMS (2.6%) and at least 180 days for DES (1.2%). Multivariate analysis confirmed these results compared to any stent implanted between 2 and 10 years before surgery (table 1).

Table 1. Adjusted Risk for 30-Day MACE After Noncardiac Surgery

The Waiting Game

The problem with patients undergoing elective surgery after stent implantation is finding a balance, Dr. Wijeysundera told TCTMD in a telephone interview. On the one hand, it is important to avoid too long a delay, especially in cases of cancer or peripheral vascular disease, while on the other, surgery after stent insertion increases the risk of adverse events such as stent thrombosis, especially if antiplatelet therapy is cut short.

The study results are consistent with prior thought that having surgery within 45 days after any stent insertion yields higher rates of adverse events, Dr. Wijensundera reported. However, he added, the increase in the rate of events after 6 months in patients with [BMS] was surprising. Still, it is consistent with clinical thought that after 6 months “one might expect restenosis to be maximal in these patients. So you should wait for a period of time after [BMS implantation] for noncardiac surgery. But on the flip side, waiting too long might not be helpful.”

For DES, halving the waiting time suggested by current guidelines could have a substantial impact on certain patients, Dr. Wijeysundera explained. “The advantage of our report is that it is across multiple hospitals in multiple settings,” he said. “That is key because if you, for example, are a patient with cancer or need surgery on a fairly urgent basis . . . being able to wait a shorter period of time and [still] undergo surgery safely is important.”

Harold L. Dauerman, MD, of the University of Vermont (Burlington, VT), agreed that the strength of the study is its large population and the fact that it is not limited to academic medical centers or certain patients, “so the overall estimates for the event rates seem to be very representative of what happens in a real-world population.”

A problem with comparing this study with other registry studies is that “everybody [uses] a different time cutoff for what [constitutes] ‘late’ surgery,” Dr. Dauerman observed. However, “what’s clear is surgery done in the first 4 to 6 weeks after PCI is at increased risk and should be avoided. Every paper [agrees] on that,” he said. “What’s still a little unclear to me—and I think that it could impact guidelines—is whether we could shorten the window from 12 months to 6 months for surgery.”

Dealing With Dual Antiplatelet Therapy

As important as determining when it is safe to proceed with surgery is defining whether or not to stop dual antiplatelet therapy, Dr. Dauerman observed. “From the data we have from prior studies, it’s never really safe to stop both aspirin and clopidogrel any time after PCI,” he said. “So if you have to [have surgery], whether [you have] a bare-metal or drug-eluting stent, the time you are on no antiplatelet therapy should be minimized, and this [interruption] should be for only very selected high-bleeding risk surgeries.”

The safety of stopping clopidogrel and continuing aspirin, however, is more established, Dr. Dauerman continued, although this study could not address the issue.

Dr. Wijeysundera agreed that more research is needed regarding what to do about dual antiplatelet therapy, but suggested, based on his clinical experience, that patients continue on aspirin. “There is certainly a role for studying what we should do with Plavix,” he said.

Leaving Room for Ambiguity

According to Dr. Dauerman, the study “could be used to help the guidelines be broadened and made deliberately more vague than they currently are so they can acknowledge that patients can get surgery 6 months after a drug-eluting stent.” The wording should allow for “some ambiguity in this area,” he added.

Since a randomized trial in this case is out of the question, the best-case scenario would be to “have a uniform definition of what early surgery after PCI means versus late surgery so that every study is comparing the same time interval for adverse events,” he said, suggesting 6 weeks and 6 months after PCI as the definitions of early and late surgery, respectively.

Having set definitions will also be important as research moves forward to study second-generation DES “for which the risk of cardiovascular events might be even lower than that seen in this study, which extends back to first-generation drug-eluting stents,” Dr. Dauerman said.

Study Details

The 16 major noncardiac surgeries were abdominal aortic aneurysm repair, carotid endarterectomy, peripheral vascular bypass, total hip replacement, total knee replacement, large bowel resection, partial liver resection, Whipple procedure, pneumonectomy, pulmonary lobectomy, gastrectomy, esophagectomy, total abdominal hysterectomy, radical prostatectomy, nephrectomy, and cystectomy.

 

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Source:
Wijeysundera DN, Wijeysundera HC, Yun L, et al. Risk of elective major non-cardiac surgery after coronary stent insertion: A population-based study. Circulation. 2012;Epub ahead of print.

 

 

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• Surgical Complications More Likely in Patients with DES