Prior Incomplete Revascularization Ups Noncardiac-Surgery MI Risk

Marlene Busko

November 15, 2016

NEW ORLEANS, LA — In a national cohort of veterans with CAD who had received at least one stent, those who had complete revascularization (PCI on all obstructive lesions) were less likely to have a major adverse cardiac event (MACE) when they had a noncardiac operation within the next 2 years[1].

Specifically, patients who had complete vs incomplete revascularization had a 19% lower risk of having MACE—defined as dying from any cause, having an MI, or needing revascularization—within 30 days of noncardiac surgery.

Moreover, each additional unrevascularized coronary artery that a patient had was associated with a 17% greater risk of having an MI following noncardiac surgery.

"Even if someone received a stent and is doing okay, they may still have unrevascularized territory," Dr Javier A Valle (University of Colorado, Denver) told heartwire from Medscape at a poster session here at the American Heart Association 2016 Scientific Sessions, The study, with lead author Dr Ehrin J Armstrong (Denver Veterans Affairs Medical Center, CO), was published online in JACC: Cardiovascular Interventions.

"The critical thing, isn't necessarily at the time that we're stenting; it's the time when someone's going to go for noncardiac surgery," Valle continued.

Even though CAD patients who have at least one stent and are about to have noncardiac surgery may have no symptoms, a formal evaluation by a cardiologist or a stress test may identify a need for complete revascularization prior to the surgery. "There is an opportunity to . . . possibly intervene up front before they develop a postoperative event," he said.

"The CARP trial[2] . . . says maybe revascularization doesn't matter as much when people are going for noncardiac surgery; it's the medical therapy through surgery that matters more," Dr James DeVries (Dartmouth Hitchcock Medical Center, Lebanon, NH), who stopped to look at the poster, observed to heartwire .

"But I think this [study] is at least raising a red flag and saying, 'revascularization does matter,' and it may be worth it to try to [completely] revascularize these people in the cath lab or elsewhere to try to reduce their risk of MACE" prior to noncardiac surgery, he said.

Current Guidelines Deemphasize Stress Testing

About 20% of noncardiac surgeries are performed in patients who have had PCI within the past 2 years, Armstrong and colleagues write.

"Current guidelines for perioperative management have suggested optimal control of risk factors and delaying surgery for a year among patients with drug-eluting stents but deemphasize the need for stress testing or evaluation for underlying ischemia in the absence of symptoms," they note.

They hypothesized that patients who had incomplete revascularization and presumed residual ischemia would be at increased risk for MACE within 30 days.

To investigate this, they analyzed data from a national cohort of veterans who had noncardiac surgery within 2 years of having PCI. The noncardiac surgeries included vascular, orthopedic, and gastrointestinal surgeries.

The researchers identified 12,486 patients who had coronary stents implanted in VA facilities between 2005 and 2010 and then had noncardiac surgery within 24 months of receiving the stent; none of the patients had undergone CABG.

In this veteran population, most patients (84%) were 60 and older; 88% were white and almost all were male (98.5%). About a third (4332 patients, 34.7%) had incomplete revascularization.

Greater Perioperative Risk in First 6 Months After PCI

A total of 567 MACE events occurred within a month of the noncardiac surgery.

More patients who had incomplete revascularization (5%) vs complete revascularization (4.3%) had the combined primary end point of MACE within 30 days (odds ratio [OR] 1.19; 95% CI 1.00–1.41; P=0.05).

This was driven by MI. More patients who had incomplete revascularization (3.3%) vs complete revascularization (2.5%) had an MI within 30 days of the noncardiac surgery (OR 1.37, 95% CI 1.10–1.70; P=0.01).

About 1.5% of the patients in who had complete or incomplete revascularization died within 30 days of the noncardiac surgery.

Incomplete revascularization was associated with a significantly increased risk of postoperative MI if the surgery was performed within 6 weeks of PCI (adjusted OR 1.84, 95% CI 1.04–2.38).

The number of vessels with incomplete revascularization predicted an increased risk of postoperative MI in a stepwise fashion.

The mechanism to explain why noncardiac surgery may result in postoperative MI may include "plaque rupture from a proinflammatory state, stent thrombosis as a result of antiplatelet interruption, or a so-called demand event due to hemodynamic stress in the setting of a fixed stenosis," according to Armstrong and colleagues.

The findings agree with other recent studies that showed that most perioperative risk occurred in the first 6 months after PCI, regardless of stent type or reason for the PCI. Thus "patients with incomplete revascularization . . . should also have surgery delayed for at least 6 weeks and ideally 6 months post-PCI based on our findings," according to the authors.

However, these are observational data and cannot show cause and effect, Valle cautioned. "While our data support an association between incomplete revascularization and adverse events, they do not prove a causal association between complete revascularization and a reduction in cardiovascular risk, which remains controversial," the researchers write, and they call for further studies.

The study was supported by a grant from the Veterans Affairs Health Services Research & Development. Armstrong is a consultant for Abbott Vascular, Boston Scientific, Medtronic, Merck, Pfizer, and Spectranetics. Valle had no relevant financial relationships. Disclosures for the coauthors are listed in the paper.

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