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A pair of studies directed by anesthesiologists from Mayo Clinic provides important new guidance for patients with coronary stents who are electing to have surgery.

A pair of studies directed by anesthesiologists from Mayo Clinic provides important new guidance for patients with coronary stents who are electing to have surgery.

Gregory A. Nuttall, MD, and his group from the Mayo Clinic College of Medicine, Rochester, evaluated 899 patients from 1990 to 2005 who had received coronary artery stents. Their research indicates that elective non-cardiac surgery performed 90 days or more after implantation of coronary stents offers the lowest risk of surgery-related death, heart attack and the need for re-opening clotted artery stents.

Coronary artery stents, whether made of metal or of a kind that leak drugs into the bloodstream, are used to open blocked arteries and restore blood flow to the heart.

This research underscores a quandary faced by an increasing number of physicians dealing with the needs of an aging population: Blood-thinning medications used to prevent clots in artery stents increase the risk of surgical bleeding, but if the medication is stopped before surgery, the patient is predisposed toward stent closure, angina and heart attacks.

According to Charles W. Hogue, Jr, MD, who wrote an accompanying editorial for the study, it is important that any exposed metal in artery stents be allowed enough time to be covered by the blood vessels' endothelial cells, and it's critical that a "dual therapy" of blood-thinning drugs such as aspirin or clopidogrel be administered to keep clots from forming in the stent.

"It is now recognized that premature discontinuation of duel blood antiplatelet therapy during this critical period is a major independent risk factor for blood clotting," said Dr. Hogue.

In response to these risks, the American College of Cardiology released a scientific advisory in 2007 that includes a recommendation to delay elective non-cardiac surgery for one year after implantation of artery stents and recommends uninterrupted blood-clotting therapy for a minimum of one month after metal stent implantation and a minimum of one year after drug-leaking stent implantation. These recommendations were based on several small studies with small sample sizes.

Dr. Nuttall's two large studies, though, represent the largest series of patients currently reported.

"Our first study found that the risk of death, heart attack and need for re-opening a clotted coronary artery stent was one in ten patients if surgery was performed 30 days or less from placement of a bare metal stent," said Dr. Nuttall. "From the time period of 30 to 90 days, the number dropped to one in 25 patients. And after 90 days, it dropped to one in 33 patients."

In a related study of drug leaking stents completed at the same time, Dr. Nuttall found that the incidence of death, heart attack and the need to re-open clotted artery stents was six per cent throughout the first year after implantation and dropped to three per cent during the second year.

"These two studies add to a growing body of literature demonstrating that timing really is everything when considering the risks and management strategy of non-cardiac surgery in patients with coronary stents," said Dr. Hogue.