The five-year study found that death rates of high-risk stroke and heart attack patients fell by 22 per cent when they took the anti-hypertensive drug ramipril.
The study, dubbed Project HOPE (Heart Outcomes Prevention Evaluation), was led by Canadian Dr. Salim Yusuf of McMaster University and Hamilton General Hospital in Toronto.
"If ramipril is widely used in high-risk patients, more than one million unnecessary deaths, heart attacks and strokes could beprevented worldwide each year," Yusuf said in a news release.
The study also found that ramipril shows a dramatic 31 per cent reduction in the risk of diabetes.
"The fact that this study showed ramipril may prevent diabetes will certainly attract a lot of attention," said diabetes specialist Dr. Hertzel Gerstein of McMaster University.
No drug has ever clearly shown that diabetes can be prevented.
"I'm sure there will be studies to replicate this, and understand how this can happen, because ... it's a bit of a novel finding," said Gerstein, co-chair of the diabetes section of the HOPE study.
Project HOPE involved about 9,500 high-risk heart patients in 267 hospitals, doctors' offices and clinics in 19 countries, including Canada, the United States, Mexico, Europe and South America. The study was presented recently at the annual European Society of Cardiology meeting in Barcelona, Spain.
Ramipril, known in Canada by the brand name Altace, reduces the risk of cardiovascular death by 25 per cent, reduces non-fatal heart attacks by 20 per cent and cuts non-fatal stroke rates by 32 per cent.
The study received financial support from the Medical Research Council of Canada and the makers of Altace - Hoechst Marion Roussel.
The obvious question now, said Dr. Anthony Graham, spokesperson for the Heart and Stroke Foundation, is why does the drug work so well?
"The why of it is a little less clear. These are blood pressure lowering medicines," said Dr. Anthony Graham, spokesperson for the Heart and Stroke Foundation Graham. "A number of the people in this study didn't have high blood pressure to begin with, but they were put on the drug because it has other positive effects."
The study will stimulate further research on ramipril, he said.
Dr. Richard Davies, director of clinical research at the Ottawa Heart Institute and a medical participator in Project HOPE, said the original focus of the study was to monitor two things: to see if there was a link between vitamin E and heart attack prevention, and if ramipril reduces strokes and heart attacks.
Researchers found no clear benefit in taking vitamin E for reducing cardiovascular illness, but will continue to test it for the next three years because preliminary evidence shows it may help prevent new cancers.
One of the important benefits othe study is that the drug may cut down costly, invasive heart procedures such as coronary artery bypass and balloon angioplasty, Yusuf said.
"These results will lead to changes in the management of cardiovascular disease," Yusuf said. "This is extremely good news for patients with heart disease."