Coronary artery bypass surgery and less-invasive percutaneous coronary intervention (PCI) both treat multiple vessel disease, but how do doctors decide which procedure is right for a patient? New data from a study of almost 8,000 participants provides that comparative effectiveness guidance.

The most important revelation is that choosing one course of treatment over the other has a major impact on long term survival specifically for patients with diabetes and older patients.

"Our aim was not just to look at overall outcomes, but to look at the possibility that the relative outcomes may vary according to patient characteristics," lead investigator Mark Hlatky, MD, professor of health research and policy and of cardiovascular medicine at Stanford University School of Medicine (Stanford, California), told Medical Device Daily.

The study found that for patients who suffer from multi-vessel coronary artery disease who have diabetes and patients older than 65, coronary artery bypass graft may be a better treatment choice than PCI. And, for patients younger than 55, PCI may be the best choice.

"The diabetes thing has been controversial for the past dozen years or so," Hlatky said. "It's still a fairly controversial issue and some trials are still ongoing now that are comparing the most recent forms of PCI with drug-eluting stents [DES] with bypass."

This study did not include DESs as a factor, just bare-metal stents. Hlatky hopes to conduct another study that will include the drug-eluting versions to further hone treatment decisions.

In addition to the lessons learned about choice of procedure, this study is the very kind being promoted by President Barack Obama one that teases out the most effective healthcare treatment choices.

"We hear a lot about comparative effectiveness research now," Hlatky said. "This study is a good example of how to do those studies to get more precise answers. That's one of the big-picture messages about the study. But in order to look at how much things might differ from averages, you need large groups of patients in studies."

Hlatky said this study was funded by the Agency for Healthcare Research and Quality (AHRQ; Rockville, Maryland) and that the government needs to support more large-scale comparative effectiveness studies.

"It was not easy to come up with government funding for this," he said. "The AHRQ did fund us and we hope they will make this part of their portfolio to support comparative effectiveness studies. We need to figure out a way to make some of these large studies easier to do.

"It's striking that we had 8,000 patients in the study worldwide and there are 600,000 patients who get PCI in the U.S. alone; 250,000 get bypass surgery," Hlatky said. "There are 2,500 patients a day who are getting one of these two procedures and we have just 8,000 patients in trials. We ought to figure out a way to enroll more patients in simpler trials."

Back to the specific trial results, the fact that age and diabetes are treatment modifiers were somewhat of a surprise to Hlatky because a previous meta-analysis of the group found no effect related to diabetes. "But with twice as many patients in this study, it's a more powerful test," he said.

Regarding diabetes, "It may be that patients with diabetes have more extensive disease and bypass takes care of more of that than angioplasty," Hlatky said. "We even corrected for two- vs. three-vessel disease and the diabetes effect still remained."

Published in the March 19 issue of The Lancet, the study found that for patients with diabetes, the mortality rate after a five-year follow-up was 12% for those who had bypass surgery compared with 20% for those who had angioplasty. For patients older than 65, the mortality rate was 11% for those who had bypass compared with 15% for those who had angioplasty.

The study did support previous findings that long-term mortality is similar after bypass or angioplasty for average patients with multi-vessel disease. But it also checked to see if this holds true in various subgroups such as women, smokers and patients with hypertension. Typical studies don't analyze these kinds of sub-group categories. A total of 10 trials provided data on 7,812 patients. PCI was done with balloon angioplasty in six trials and with bare-metal stents in four trials.

Going forward, Hlatky suggests that cardiologists should consider patients' age and whether or not they have diabetes when choosing between PCI and bypass surgery.

"I think that patients with diabetes should have extra consideration for whether bypass will help the most or not," he said. "Sometimes people consider PCI at the time of catheterization because it's easy to do then. But if there are fairly extensive lesions, one might think about bypass."

Hlatky added: "Critics will say we didn't have DES in the study, but personally I would think it wouldn't make a difference. Age is the other significant modifier of the treatment effect. The older you got, the more bypass helped. The reasons for that need to be explored further."

"This is the kind of research we're hoping to have more of so that clinicians and policy makers and patients can make informed decisions," said Douglas Owens, MD, senior investigator at the Veterans Affairs Palo Alto Health Care System (Palo Alto, California) and professor of medicine at Stanford.

Costs for bypass surgeries and angioplasty procedures total more than $100 billion annually in the U.S., making it an obvious target for continued comparative effectiveness studies.

Results from this study come at a time when policy makers have just made a $1 billion investment in comparative effectiveness. Fifteen members were recently named to the new Institute of Medicine (Washington) Committee on Comparative Effectiveness Research Priorities to oversee that investment (MDD, March 23, 2009).

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