(Ivanhoe Newswire) -- It may be a more invasive surgery, but new research shows heart bypass surgery leads to longer lives than angioplasty for specific groups of patients.

A new study involving nearly 8,000 patients from 10 clinical trials around the world shows heart patients who have diabetes and are older than 65 have lower mortality rates after five years if they had bypass surgery compared to those who had angioplasty.

The death rate for diabetics after a five-year follow-up was 12 percent for those who had coronary artery bypass surgery compared with 20 percent for the angioplasty procedure. For those patients over 65, the mortality rate was 11 percent for those who had bypass compared with 15 percent for those who had angioplasty.

This is one of the first major studies to determine if one active treatment is better than another, rather than just gauging whether a treatment works better than a placebo, the study's authors said.

David Taggart, M.D., Ph.D., professor of cardiovascular surgery at the University of Oxford, called the study "the most definitive and authoritative analyses" of randomized trials comparing bypass surgery to angioplasty in an accompanying editorial.

"It took some time to get individual patient data from all the participating trials, but it was worth it because the pooled analysis is much more valuable if it's based on essentially all the data. In the end we were able to analyze data from 95 percent of all the patients worldwide with multi-vessel coronary disease enrolled in a clinical trial of bypass surgery and angioplasty," Taggart was quoted as saying.

The study's authors said they hope future studies will determine why bypass surgery is more effective for treating diabetic and older patients.

SOURCE: Published on The Lancet's Web site on March 19, 2009