NEW YORK (Reuters Health) - Ten-year results from a comparison of coronary-artery bypass grafting (CABG) with medical therapy alone has found that bypass lowers the odds of cardiovascular death by about nine percentage points in people with ischemic cardiomyopathy.

The 16% reduction in the death rate meant volunteers who received bypass grafting typically lived nearly a year and a half longer than those who received optimal nonsurgical therapy.

The findings are based on a study population of 1,212 patients with an ejection fraction of 35% or less who received bypass grafts between 2002 and 2007.

Death from any cause, the primary endpoint, occurred in 66.1% of the control patients and 58.9% of the bypass recipients (p=0.02).

When the researchers looked exclusively at cardiovascular deaths, the rates were 49.3% in the medical-therapy group and 40.5% in the group receiving bypass in addition to standard medical care (p=0.006).

The combined odds of hospitalization or death from any cause were also lower with bypass.

For death or hospitalization for cardiovascular causes, there was a 10.4 percentage point difference (p<0.001). For death or hospitalization for heart failure, the difference was 8.6 points (p<0.002). It was for 6.4 percentage points for death or hospitalization for any cause (p=0.001).

Results from the study, known as STICHES, were released April 3 at the American College of Cardiology annual scientific session in Chicago and online by the New England Journal of Medicine.

Bypass grafting "was associated with more favorable results than medical therapy alone across all clinically relevant long-term outcomes we evaluated," said the team, led by Dr. Eric Velazquez of the Duke Clinical Research Institute at Duke University, Durham, North Carolina.

The trends "resulted from a persistent and perhaps increasing effect size over time," they said. "Thus, it appears that the operative risk associated with CABG is offset by a durable effect that translates into increasing clinical benefit to at least 10 years."

Coronary artery disease kills more than 538,000 people in the United States each year. Most of the studies establishing the benefits of bypass grafting were done more than 40 years ago.

The initial version of the new study was known as STICH and it followed patients at 99 sites in 22 countries for a median of just over four and a half years. It found no significant difference between the two treatments when it came to the rate of death from any cause. However, bypass recipients were less likely to die from a cardiovascular event or to die from any cause or be hospitalized for cardiovascular causes.

STICHES extends those results to 10 years and found that any-cause death became significant.

Median survival was 7.73 years with bypass and 6.29 years without. The researchers calculated that the number needed to treat to prevent one death was 14 patients. The number needed to prevent one death from a cardiovascular cause was 11.

Other secondary measures were the rates of death combined with specific cardiovascular events. Once again, they consistently found a benefit for bypass.

There was a 15.8 percentage point difference for any cause of death or revascularization (p<0.001). For death or nonfatal myocardial infarction the difference was 6.3 points and it was for 7.2 percentage points for death or nonfatal stroke (both p=0.03).

Among the 610 people originally assigned to the bypass group, 9% did not receive a graft before the end of the trial. In the 602 assigned to medical therapy alone, 19.8% underwent bypass surgery. Eleven percent had it within the first year.

In an accompanying editorial, Drs. Robert Guyton and Andrew Smith of Emory University in Atlanta, wrote, "The STICHES 10-year results firmly extend the survival benefit of CABG in patients with advanced coronary artery disease to patients with heart failure and severe ischemic cardiomyopathy. These findings should prompt strong consideration of coronary bypass as an addition to medical therapy in shared decision making with these patients."

The National Heart Lung and Blood Institute funded this research. Two coauthors reported disclosures.

Ten-Year Results Find that Bypass Lowers the Odds of Cardiovascular Death