Study Examines Surgery Risks in Stented Patients

In patients who had received a stent, the factors most strongly associated with major adverse cardiac events (MACE) following noncardiac surgery included a nonelective indication, a history of recent myocardial infarction (MI), and an elevated cardiac risk, researchers found.

In an adjusted model, the three strongest predictors of MACE were nonelective surgery (OR 4.77, 95% CI 4.07-5.59), a history of MI in the 6 months before surgery (OR 2.63, 95% CI 2.32-2.98), and a revised cardiac risk index indicating at least a moderate level of risk at the time of surgery (OR 2.13, 95% CI 1.85-2.44), according to Mary Hawn, MD, MPH, of the University of Alabama at Birmingham, and colleagues.

The timing of the operation relative to when the stent was implanted was a weaker predictor, and the stent type -- drug-eluting versus bare-metal -- was not significantly associated with adverse events at all. In addition, whether antiplatelet therapy was stopped or continued was not related to the likelihood of having a MACE after surgery, the researchers reported online in the Journal of the American Medical Association.

The results were presented simultaneously at the American College of Surgeons meeting in Washington.

"The present findings suggest that underlying surgical and cardiac risk, rather than stent type, are the primary factors associated with perioperative MACE, that event rates stabilize by 6 months, and that antiplatelet therapy continuation does not substantially mitigate risk," Hawn and colleagues wrote.

"Accordingly, the current focus of the guidelines on differential timing recommendations by stent type may warrant reconsideration, and greater concentration may need to be placed on assessing and optimizing cardiac risk," they wrote, acknowledging that the observational study design renders the findings hypothesis-generating only.

About one out of every five patients who receive a stent will need a noncardiac operation within 2 years, and questions remain about how long to wait until performing surgery after implantation and whether to continue antiplatelet therapy.

Guidelines from the American College of Cardiology and the American Heart Association recommend delaying elective noncardiac surgery until 1 year after implantation of a drug-eluting stent. The wait time is just 4 to 6 weeks after implantation of a bare-metal stent, although the evidence backing both recommendations is conflicting.

To explore the factors associated with development of adverse cardiac events following noncardiac surgery in patients with coronary stents, the researchers turned to a national cohort of patients who had a stent implanted within the Veterans Affairs system from 2000 to 2010. The retrospective analysis included 28,029 patients who underwent 41,989 operations within 2 years of receiving their stent.

The rate of MACE -- which included all-cause death, MI, and cardiac revascularization -- within 30 days of surgery was 4.7%.

The MACE rate was highest when the interval between stenting and surgery was less than 6 weeks (11.6%) and then declined to 6.4% with an interval of 6 weeks to less than 6 months, 4.2% from 6 to 12 months, and 3.5% from 1 to 2 years, indicating a stabilization after 6 months.

Neither stent type nor cessation of antiplatelet therapy was significantly associated with MACE risk.

"The study by Hawn et al. provides good scientific evidence to a field and a common clinical question that have been, and continue to be dominated by expert opinion," according to Emmanouil Brilakis, MD, PhD, and Subhash Banerjee, MD, of the University of Texas Southwestern Medical Center in Dallas.

They said the approach for noncardiac surgery after implantation of a bare-metal stent should not change, but suggested that the interval between stenting and surgery could be shortened to 6 months.

"Although the evidence is not definitive, continuing antiplatelet therapy during the perioperative period could decrease the risk of stent thrombosis and may carry low risk for bleeding, especially for minor surgeries; urgent surgeries can be performed before 6 months, if dual or at least single antiplatelet therapy can be continued," Brilakis and Banerjee wrote.

Regardless of stent type, "patients with coronary stents should ideally undergo surgery at centers with primary percutaneous coronary intervention capability, to allow prompt treatment if perioperative stent thrombosis occurs," they wrote.

The study authors acknowledged some limitations of their study, including the mostly older male patient population, the lack of information on factors that went into the choice of stent, the fact that some patients underwent more than one PCI during the study period, the variety of operation types, and the use of outcome data from administrative sources.

Source: www.medpagetoday.com