Patients with a mild form of clogged arteries are twice as likely to die from bypass surgery as they are from angioplasty, in which a balloon is inflated inside the arteries to open them up, according to the first major study to compare the two procedures directly.
The study appears to raise some serious questions about the use of bypass surgery in such low-risk patients, its authors said.
They added that the difference in risk between the two procedures was probably even higher now because the study involved patients treated during 1985, when angioplasty was first being widely used.
The death rate for angioplasty has fallen since then, while that for bypass surgery has remained stable, according to Dr. Arthur J. Hartz, a clinical epidemiologist at the Medical College of Wisconsin and primary author of the study.
Cardiovascular surgeons, however, charged that the study -- published in the most recent issue of the American Journal of Cardiology -- was misleading because a much larger number of such low-risk patients were now directed to angioplasty than was the case when the study data were collected. For patients with a more severe form of clogged arteries, the study showed, the two procedures have about equal risk.
"This an enormously important study," said Dr. David B. Pryor, a cardiologist at the Duke University Medical Center and another of the study's authors. "We shouldn't assume that all patients are the same" in selecting the proper form of treatment.
More than 370,000 patients have bypass surgery each year, and another 250,000 have angioplasty. Because of the large numbers of patients involved, it is important to know which of the two procedures is better and safer. That information has not been available.
One leading cardiologist called the new study "an unfair comparison" because, he said, the researchers weren't able to get all the information they needed to make an accurate assessment of risks.
Dr. Gerald M. Pohost, who is at the University of Alabama at Birmingham and also chairs the American Heart Association's Council on Clinical Cardiology, noted that bypass surgery was used more often on patients with more serious disease, who were thus more likely to die in the year after surgery.
Furthermore, the patients involved in the study were all over age 65 and thus at a higher risk of dying from surgery of any kind, said Dr. Lawrence Cohn, chief of cardiac surgery at Brigham and Women's Hospital in Boston.
"At first blush, it sounds like a problem, but in the light of day, the risks are almost equivalent," Dr. Cohn said.
Clogged arteries create the crushing pain known as angina.
Dr. Hartz and his colleagues based their study on government records for all 96,666 Medicare patients who had bypass surgery or angioplasty in 1985.