Stents Affect Post-Surgery Heart Risks

Coronary stent placement may raise risk of cardiac events within six months of noncardiac surgery

(RxWiki News) Stenting is a common way to treat atherosclerosis or clogged arteries. For patients who are having noncardiac surgery after stent placement, timing is everything.

A stent is a tiny wire mesh tube that props open an artery that has become narrowed by a buildup of fatty deposits called plaque. Stenting can restore blood flow to the heart and reduce the chances of having a heart attack.

Patients who undergo noncardiac surgery (surgery unrelated to the heart) too soon after stent placement, however, may raise the likelihood of having a heart attack, according to a new study.

"Allow sufficient time after stenting before noncardiac surgery."

Mary Hawn, MD, in the Section of Gastrointestinal Surgery at the University of Alabama at Birmingham and the Center for Surgical, Medical Acute Care Research and Transitions, Birmingham Veterans Administration (VA) Hospital, and colleagues conducted this study to determine risk factors for adverse cardiac events in patients undergoing noncardiac surgery within 24 months of coronary stent implantation.

Dr. Hawn and her team reported that, each year, about 600,000 patients in the US have percutaneous coronary stent procedures, which are performed via needle puncture to the skin. About 12 to 23 percent of these individuals have noncardiac surgery within two years of their stent placement.

The investigators reviewed results of 124,844 coronary stent implantations. About 28,000 patients (just over one in five) underwent noncardiac operations resulting in 1,980 major adverse cardiac events (MACE).

The authors noted that stent placement was linked with MACE, but it was mostly an issue for those who had had surgery within the first six months of a stent procedure. Surgery six months after stenting was “...not significantly associated with MACE.”

Nonelective surgery (within six months) was one of three significant risk factors for having MACE (an adjusted 3.79 times greater risk than those who did not have surgery).

The other biggest predictors that a person with stents may have a major heart episode were a history of heart attack six months prior to surgery (an adjusted 2.53 times the risk than those without heart attack) and a revised cardiac risk index score greater than 2 (about twice the risk of those with a score under 2).

A cardiac risk index score is a method used to assess an individual’s risk of having heart trouble by looking at factors such as that person's history of heart disease and history of heart failure.

Beyond six months after stent implantation, MACE was associated with emergency surgery and advanced cardiac disease but not stent type or timing. Stent type may be drug-eluting stents (DES) or bare metal stents (BMS).

American Heart Association and American College of Cardiology guidelines recommend delaying elective surgery for four to six weeks for BMS implantation and for at least one year after DES implantation so patients can complete antiplatelet therapy (such as low-dose aspirin) to prevent blood clotting (thrombosis).

When scientists reviewed 284 matched pairs of patients, however, they found no connection between ending antiplatelet therapy and increasing risk of MACE.

In an accompanying editorial, Emmanouil Brilakis, MD, and Subhash Banerjee, MD, of the VA North Texas Health Care System in Dallas, wrote, “The approach for patients with BMS should not change; these patients usually can undergo surgery within 6 weeks after coronary stent implantation with very low risk of stent thrombosis.

"For patients with DES, surgery performed at least 6 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, non-urgent operations should be postponed until 6 months after stent implantation," they wrote.

This study was published in the Journal of the American Medical Association (JAMA) and released to coincide with its presentation at the American College of Surgeons 2013 Annual Clinical Congress on October 7. The study was supported by a VA health Services Research & Development grant.

Review Date: 
October 7, 2013