Diabetics and Elderly May Fare Better With Bypass
FRIDAY March 20, 2009 -- A major international study pinpoints which people with major heart artery blockages would be better off having bypass surgery than artery-opening angioplasty.
"Bypass surgery is preferable for people with diabetes and older patients," said Dr. Mark Hlatky, professor of health research and policy and cardiovascular medicine at Stanford University and lead author of a report published online in The Lancet. "We used 65 as the cutoff point and, as age went up, so did the benefit of bypass surgery."
Hlatky led a group that looked at survival data on almost 8,000 people treated in 10 trials worldwide. Overall, the death rate over an average of nearly six years was almost the same for those who had bypass surgery (15 percent) and those who had what is formally called percutaneous coronary intervention, or PCI (16 percent).
But analysis showed that people with diabetes were 30 percent less likely to die if they had bypass surgery rather than PCI. People 65 and older who had bypass surgery had a mortality rate of 20 percent, compared with 24 percent for PCI.
The study is a prime example of the relatively new approach called comparative effectiveness research, Hlatky said. Most controlled trials look at the effects of giving a treatment and giving no treatment, he said. The new approach is to determine the most effective treatment "so that we can tailor the treatment to individuals," Hlatky said.
The U.S. government has allocated $1.1 billion of the economic stimulus package to fund comparative effectiveness research in hopes of getting the maximum effect from dollars spent on health care.
His study pioneered in several ways, Hlatky said. Rather than looking at the end results of published studies, it pooled data on individual participants in those studies -- an idea proposed in 1995 by Stuart Pocock of the London School of Hygiene and Tropical Medicine and senior author of the report.
The studies analyzed in the new report were done before the use of drug-coated stents, the flexible tubes implanted after PCI, had become common. But Hlatky noted that that did not affect the conclusions of the report.
"Every comparison of coated stents and bare-metal stents has shown no difference in mortality," he said. "The difference is in the number of repeat procedures required."
Some cardiologists have been reluctant to perform bypass surgery, because it carries more immediate risk than PCI. The study found a 1 percent incidence of complications from bypass procedures, compared with half of 1 percent for PCI. But Hlatky said that difference is overwhelmed by the long-term survival data.
"We know you have a higher risk upfront," he said. "You are willing to take that risk if you know the longer outcome is more favorable."
The diabetes finding "is not terribly surprising," said Dr. L. David Hillis, chairman of the department of medicine at the University of Texas Health Science Center in San Antonio. Studies reporting improved survival with surgery in diabetics were published as long as 10 years ago, and the U.S. National Heart, Lung, and Blood Institute is starting a study to confirm those findings, Hillis said.
He described the reported benefit of surgery in older people as "somewhat surprising, because you would think that, as people grow older, the risk of surgery goes up -- so this is the opposite of what you would predict."
But the definition of "old" in the new study provides one possible explanation, Hillis said. "There were almost no patients over the age of 75," he said. "They are talking about people ages 65 to 75. There were no really very old people in the study."
Another possible explanation is that older people are likely to have more extensive blockage of the heart arteries, and surgery is always better in such cases, Hillis said.
The U.S. National Heart, Lung, and Blood Institute has more on coronary artery disease.
Posted: March 2009
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