Clinical effectiveness of coronary stents in the elderly

Mar 29 2009

Heart disease patients 65 and older who receive stents coated with medicine to prevent blockages are more likely to survive and less likely to suffer a heart attack than people fitted with stents not coated with medication, according to a new study supported by HHS' Agency for Healthcare Research and Quality and the American College of Cardiology's National Cardiovascular Data Registry.

The comparative effectiveness study of 262,700 Medicare patients who received stents - spring-like tubes to keep heart vessels open - is the largest ever to compare drug-coated stents with bare metal ones. It is being presented March 28 at the American College of Cardiology's 58th Annual Scientific Session in Orlando, Florida.

A team of researchers from Duke University, AHRQ and Kaiser Permanente found that, compared with patients who received bare metal stents, those fitted with stents coated with medication, called drug-eluting stents, had an 18 percent better survival rate over the 30-month study period and were 16 percent less likely to suffer a heart attack.

"The findings provide important new evidence for decision making by heart disease patients and their physicians," said AHRQ Director Carolyn M. Clancy, M.D. "These results should help resolve many lingering questions regarding the safety of drug-eluting stents in recent years."

HHS' Food and Drug Administration approved two stents coated with drugs in 2003 and 2004, but then issued precautionary advisories in 2006 after receiving scattered reports of blood clot formation, or thrombosis, and deaths. Subsequent clinical trials and other studies produced conflicting results.

The researchers in the AHRQ-funded study found that 16.5 percent of the patients implanted with bare metal stents died within 30 months of implantation, compared with 13.5 percent of those with drug-eluting stents, after adjusting for population differences. They also found that 8.9 percent of the patients with bare metal stents suffered heart attacks during the period, compared with 7.5 percent of those with drug-eluting stents - a 16 percent higher rate. The researchers further found that patients fitted with drug-eluting stents in 2005 and 2006 had a lower risk of death than those given the stents in 2004.

"Some previous studies have suggested that drug-eluting stents are associated with an excess long-term death rate, whereas others have not," said the study's lead author, Pamela S. Douglas, M.D., Geller professor of medicine at Duke University.

The researchers found no significant differences in the percentages of drug-eluting and bare metal stent patients who required a repeat angioplasty or coronary artery bypass graft surgery (roughly 23 percent) and in the percentages of patients who suffered strokes or major bleeding (about 3 percent and 3.5 percent, respectively). The results were not affected by age, gender, race, ethnicity or other factors.

According to AHRQ's Art Sedrakyan, M.D., Ph.D., a co-author of the study, the better outcomes found for patients with drug-eluting stents may be at least partially explained because those patients are required to take blood-thinning drugs, such as clopidogrel, for a long time after their procedure. Patients who receive bare metal stents are usually prescribed blood-thinner medications for a shorter period of time and may take them less often. In addition, patients with drug-eluting stents may visit their doctors more often after hospital discharge and may receive prescriptions for drugs and therapies to lower their cholesterol levels and manage other heart conditions more often than patients who received bare metal stents.

The researchers based their study on data from the American College of Cardiology's National Cardiovascular Data Registry on patients who underwent angioplasty with drug-eluting or bare metal stent implantation at 650 hospitals, together with Medicare national claims data to capture post-hospital discharge information. The authors call for longer follow-up studies to further support the study's results and to confirm the possible effects of post-implantation treatment with blood-thinning drugs such as clopidogrel.

The study, "Clinical Effectiveness of Coronary Stents in the Elderly: Results from 262,700 Medicare Patients in ACC-NCDR," will be published online on March 28 at 9:30 a.m., to coincide with Dr. Douglas' presentation at the American College of Cardiology's 58th Annual Scientific Session. This study was funded through AHRQ's DEcIDE (Developing Evidence to Inform Decisions about Effectiveness) research network, which is part of the agency's Effective Health Care Program. The Effective Health Care Program sponsors the development of new scientific knowledge through studies on the outcomes of health care technologies and services. For more information about AHRQ's Effective Health Care Program and the DEcIDE Network, visit the Effective Health Care Web site at http://effectivehealthcare.ahrq.gov/.

http://effectivehealthcare.ahrq.gov/