With few effective options for heart failure patients, the findings could give patients a potential new treatment and could change the dietary recommendations for them, said Dr. Jose Gonzalez Juanatey, a spokesman for the European Society of Cardiology, who was not connected to the research.
"This reinforces the idea that treating patients with heart failure takes more than just drugs," Juanatey said.
The study findings were published online in the medical journal The Lancet on Sunday. They were simultaneously announced at a meeting of the European Society of Cardiology in Munich.
"With a lot of these patients, you have no other choice," said Dr. Helmut Gohlke, a cardiologist at the Heart Centre in Bad Krozingen, Germany. "They've tried other treatments and are at the end of the road."
Italian researchers gave nearly 3,500 patients a daily omega-3 pill, a prescription-formulation pill derived from fish oils, produced by Norway's Pronova BioPharma.
But doctors said people should get the same benefits from taking cheaper options like fish oil supplements -- or just eating more oily fish like salmon.
Roughly the same number of patients were given placebo pills. Patients were followed for an average of four years.
In the group of patients taking the fish oil pills, 1,981 died of heart failure or were admitted to the hospital with the problem. In the patients on placebo pills, 2,053 died or were admitted to the hospital for heart failure.
In a parallel study, the same team of Italian doctors gave 2,285 patients the drug rosuvastatin, also known as Crestor, and gave placebo pills to 2,289 people. Patients were then tracked for about four years. The doctors found little difference in heart failure rates between the two groups.
Comparing the results from both studies, the researchers concluded that fish oil is slightly more effective than the drug because the oil performed better against a placebo than did Crestor.
"It's a small benefit, but we should always be emphasizing to patients what they can do in terms of diet that might help," said Dr. Richard Bonow, chief of cardiology at Northwestern University Hospital in Chicago and past president of the American Heart Association.
Both studies were paid for by an Italian group of pharmaceuticals including Pfizer Inc., Sigma Tau SpA and AstraZeneca PLC.
Omega-3 fatty acids from fish such as salmon and tuna have long been proven to offer health benefits like protecting the heart and brain, though scientists aren't exactly sure how.
Bonow said that since cell membranes are made of fatty acids, fish oils may help to replace and strengthen those membranes with omega-3.
Fish oils also are thought to increase the body's good cholesterol levels, as well as possibly stabilizing the electrical system in heart cells, to prevent abnormal heart rhythms.
In contrast, statins act on the body's bad cholesterol, which may not have a big impact on heart failure.
Previous studies that investigated the benefits of omega-3 fatty acids have largely been observational, and have lacked a direct comparison to a placebo. It has also been unknown whether taking fish oil supplements would be as good as eating fish.
"This study changes the certainty of the evidence we have about fish oils," said Dr. Douglas Weaver, president of the American College of Cardiology.
Weaver said that guidelines in the United States would likely change to recommend that more heart patients eat more fish or take supplements. "This is a low-tech solution and could help all patients with cardiovascular problems."
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