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Risk and outcome similar for bypass surgery, drug-eluting stents

April 20, 2007

American Heart Association meeting report

Drug-eluting stent therapy and bypass surgery for coronary artery disease have about the same risk for a major cardiac event within 30 days after the procedures, researchers reported at the American Heart Association's 8th Annual Conference on Arteriosclerosis, Thrombosis and Vascular Biology.

The two also have similar outcomes three years after treatment. Patients with coronary arteries narrowed by atherosclerosis are often candidates for either bypass surgery to reroute the arteries' blood flow or a stent, which is a small mesh tube that helps keep arteries open after angioplasty, a procedure to open clogged arteries.

Previous studies have found that placing bare-metal stents is safer than bypass surgery. However, "bypass surgery is much more successful for restoring patients' blood flow in the long-term because arteries with traditional stents re-narrow in about one out of every three cases," said James M. Wilson, M.D., senior author of the study. The newer drug-eluting stents were developed to help keep arteries open longer, but until now their effectiveness had not been compared with the gold standard bypass surgery.

Wilson and colleagues analyzed 799 drug-eluting stent patients and 799 coronary bypass patients, comparing how they fared in the first 30 days after their procedures and during the next three years.

"What we found came as a bit of a surprise," said Wilson, program director of the Cardiology Fellowship Program at St. Luke's Episcopal Hospital and Texas Heart Institute in Houston. "We found that the likelihood of any complication in the hospital was the same whether you had a drug-eluting stent or bypass. Five percent of drug-eluting stent patients had some major complication in the hospital, mostly heart attack, as opposed to about 3.8 percent of the patients who had bypass. Those numbers, although seemingly different, are statistically the same."

"We have done further research since comparing drug-eluting to bare-metal stents and have found that the higher complication rate among drug-eluting patients is not due to the technology but rather patient selection," said Wilson, who is also assistant chief of cardiology at St. Luke's Episcopal Hospital. "Now that we have more confidence in the long-term effectiveness of the drug-eluting stents, we are using the technology on much sicker patients."

Drug-eluting stents were better than bare-metal stents when compared to bypass surgery in terms of survival, with no statistically significant difference between the drug-eluting stents and bypass groups. Researchers reported that the death rate at three years with bypass was 6.6 percent and 9 percent after drug-eluting stent therapy.

The research suggests that if doctors use drug-eluting stents in patients who are lower risk, they might expect even more favorable results, said Muhammad S. Munir, M.D., lead author of the study and a nonclinical research fellow at the Texas Heart Institute.

"If the patient selection is made less aggressively or more optimally, it may give drug-eluting stents better results in the long run, making drug-eluting stents emerge as a treatment that would be better than all other contemporary methods," Munir said.

Wilson said it's best, "sticking to what we do well. We have reported that the risk of bypass surgery and drug-eluting stents is the same among high-risk patients. So, if we choose the patients we know we can treat well with stents, then it is reasonable to treat them by a catheter rather than by surgery. If we can't do a good job with stents, then bypass is the better choice."

American Heart Association