BOSTON -- Patients who take aspirin within two days of heart bypass surgery dramatically reduce their health risks, Reuters quoted researchers as saying on Wednesday in a finding that could save 25,000 lives worldwide each year.

The conclusion challenges the conventional wisdom that has kept bypass surgery patients off the cheap, generic pain-killer amid fears it would lead to dangerous bleeding.

Such thinking is not only wrong but also probably contributes to some 9,000 deaths each year in the United States alone, according to a $35 million study published in this week's New England Journal of Medicine.

The study's authors found that giving heart bypass patients aspirin within 48 hours of surgery cut the death rate by 68 percent during the study period.

The chances of stroke decreased by 62 percent, the likelihood of kidney problems fell by 60 percent, and the risk of developing a heart attack was nearly cut in half.

Aspirin substantially mitigates both fatal and nonfatal damage to the heart, brain, kidneys and intestines, said the team of researchers, led by Dennis Mangano of the San Francisco-based Ischemia Research and Education Foundation.

"Contrary to current belief, aspirin therapy was safe and was not associated with an increased risk of bleeding, gastritis, infection, or impaired wound healing," the researchers said.

Editors of the journal said a formal clinical trial is needed before aspirin therapy becomes routine, and Robert Bonow, president of the American Heart Association, said there was still reason for caution.

But Mangano said that instead of waiting five years for a clinical trial to be completed, doctors should apply his team's findings immediately -- a move he said would save 25,000 lives each year worldwide and prevent 50,000 complications at very little cost.

"Quite Striking" Mangano's foundation is an independent, non-profit organization that does clinical trials for the government and pharmaceutical companies. It used income from those trials to fund the aspirin study, Mangano said, because no drug company is going to pay for a study of a cheap generic drug like aspirin.

Eric Topol of the Cleveland Clinic Foundation called the findings "quite striking" and said that until it is shown to be hazardous, early aspirin use after bypass surgery should become standard practice.

"The benefits appear to be important and overriding," Reuters quoted Topol as writing in an editorial in the journal, adding there was evidence to suggest that the Mangano study underestimated the benefits of aspirin.

Regular use of aspirin, even a small daily dose, is already known to reduce the risk of heart attack by 34 percent and stroke by 25 percent.

Topol said the new results lend support to last year's recommendation by the American College of Chest Physicians that patients be given 325 milligrams of aspirin per day -- the equivalent of one regular-strength tablet -- starting six hours after bypass.

The best time for aspirin may even be as early as one hour after surgery, Topol said.

Mangano said it now appears that patients who are already taking aspirin regularly should continue taking it before and immediately after surgery, and those who aren't taking it should be given the drug soon after the operation.

But Bonow disagreed, saying it is still unclear whether patients should be taking aspirin up to and through the operation.

Previous studies have shown that people with aspirin in their system tend to have more complications immediately after surgery, possibly because the drug interferes with the clot-forming platelets that the patient may need to join the pieces of flesh that have been cut by the surgeon.