Study shows Bypass surgery better than angioplasty for diabetics

• Diabetes • Sep 20, 05

Severe coronary heart disease can be treated with either heart bypass surgery or angioplasty with similar survival rates, according to findings of a five-year, international study published in the July 25 issue of the New England Journal of Medicine. However, in those patients who were also treated for diabetes (20 percent of the study’s participants), bypass surgery provided significantly better survival than angioplasty, reports the authors of the largest clinical trial comparing the two procedures.

The multi-center Bypass Angioplasty Revascularization Investigation (BARI) was coordinated at the University of Pittsburgh.

“This study should have an important impact on the way diabetics with coronary artery disease are treated,” according to Katherine Detre, M.D., Dr.P.H., principal investigator for the study’s coordinating center at the University of Pittsburgh Graduate School of Public Health.

The study was funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health and was designed to compare the long-term safety and efficacy of the two procedures in patients with multi-vessel coronary artery disease. It also looked at quality of life, the need for repeat procedures, incidence of heart attack and angina and cost of treatment. Conducted at 16 centers in the United States and two centers in Canada, it is the largest randomized clinical trial to compare bypass surgery and angioplasty and is the first to report on the outcome of these procedures among diabetic patients. Preliminary results in diabetics were so dramatic that a clinical alert detailing the findings was issued to doctors last fall by the NHLBI.

In addition, a presentation was made at the annual meeting of the American Heart Association by BARI Study Chairman Robert Frye, M.D., who is from the Mayo Clinic Foundation.

“The BARI study offers vitally important information on the relative risks and benefits of these two procedures,” said Dr. Claude Lenfant, NHLBI director.

Between 1988 and 1991, a total of 1,829 patients with multi-vessel heart disease were enrolled and randomly assigned to one of the two procedures. Patients were followed for an average of 5.4 years.

“Our analysis revealed no statistically significant difference in survival between the two treatment strategies,” according to Kim Sutton-Tyrrell, Dr.P.H., co-principal investigator and associate professor of epidemiology. “Patients who underwent heart bypass had a survival rate of 89.3 percent, and those assigned to angioplasty had a survival rate of 86.3 percent.”

However, in a subgroup of 353 drug-treated diabetic patients, those who had bypass surgery had an 80.6 percent survival rate, while those who underwent angioplasty had a 65.5 percent survival rate.

“The more extensive coronary artery disease among diabetics and the greater tendency for their arteries to reclog after angioplasty suggest potential reasons to explain the relatively better outcome after bypass surgery,” said Dr. Detre, who is a professor of epidemiology. “The influence of these and other factors requires further study.

“It is important to note that the findings for diabetic patients applies only to those who are being treated with insulin or oral hypoglycemic agents for their diabetes, have multiple coronary artery blockages and are first-time candidates for one of the procedures,” she added.

The study also found that of the bypass patients, eight percent underwent additional revascularization procedures in the first five years; 54 percent of the angioplasty group underwent at least one subsequent procedure, most often in the first year of follow-up. The median hospital stay was seven days following bypass surgery and three days following angioplasty. However, in the long-term, because of repeat procedures, angioplasty patients spent more time in the hospital than bypass patients.

“In spite of the greater need for reintervention, 69 percent of the patients who underwent angioplasty avoided subsequent bypass,” Dr. Detre noted. “For patients who prefer to avoid major surgery, angioplasty offers a reasonable alternative with an expectation of similar overall survival rates.”

The study also found that rates of in-hospital mortality and stroke were similar in the two treatment groups.

Some 362,000 angioplasties and 309,000 bypass surgeries are performed annually in the United States. The typical cost of angioplasty is about $15,000, and bypass, $30,000.

About 14 million people in the United States have diabetes, which is a major risk factor for coronary artery disease. About 65 percent of diabetics die from some form of heart or blood vessel disease.
University of Pittsburgh Medical Center, Pittsburgh