Bypass surgery is more likely than angioplasty (with or without a stent) to relieve angina associated with coronary artery disease and less likely to require a second procedure, according to a report released by the U.S. Agency for Healthcare Research and Quality, part of the Department of Health and Human Services. A summary has been published online by Annals of Internal Medicine.

The analysis drew on 23 randomized controlled trials that compared treatments for patients with mid-range coronary disease treatable with either angioplasty or bypass surgery. As defined by the report, mid-range disease occurs in three ways: a single blockage of the left anterior descending artery, blockage of two arteries or some forms of less-severe blockage of three arteries.

The report also found that bypass surgery and angioplasty had about the same survival rates and similar numbers of myocardial infarctions, but bypass surgery presented a slightly higher risk of stroke within 30 days of the procedure.

“Choosing a treatment for coronary disease has long been a difficult challenge,” said AHRQ Director Carolyn M. Clancy, MD. “But this new evidence-based report provides a vital reference to help doctors, patients, and their families make the best possible decision.”

For many patients, the best treatment choice is clear. For those with most extensive disease that limits blood flow in several arteries, bypass surgery is typically used. For those with the least extensive disease, angioplasty is the standard choice. The new federal study, funded by AHRQ’s Effective Health Care program and completed by the Agency’s Stanford-UCSF Evidence-based Practice Center, compared the outcomes and risks of the procedures in patients with mid-range coronary disease, where either procedure might be chosen.

Analysis revealed that the likelihood of surviving 30 days beyond the procedure was roughly 98.5 percent for both types of procedure. Although more research is needed to clarify long-term survival benefits for bypass and angioplasty, about 96 percent of patients live at least a year after both types of procedure and roughly 90 percent live five years or longer.

Roughly 84 percent of patients who undergo bypass surgery are free of angina one year after the procedure compared with about 75 percent of patients who receive angioplasty. The difference narrows with time but remains substantial five years after treatment.

About 4 percent of patients who have bypass surgery undergo a repeat procedure within one year, and 10 percent within five years. The need is significantly higher among patients who receive angioplasty - 24 percent more at one year and 33 percent more at five years.

About 0.6 percent more patients receiving bypass have a stroke during the first 30 days after the procedure than patients receiving angioplasty.

Studies that measured patients’ quality of life six months to three years after undergoing the procedures found significantly more improvement for bypass surgery patients than for balloon angioplasty patients. The difference, which equalizes after three years, was attributed to angina relief.

The new report, “Comparative Effectiveness of Percutaneous Coronary Interventions and Coronary Artery Bypass Grafting for Coronary Artery Disease,” is available online at http://effectivehealthcare.ahrq.gov.