The findings suggest that the drug, already used to treat advanced heart failure, also has value for people with mild disease, says study leader Faiez Zannad, MD, PhD, of Nancy University in Nancy, France.
The results were reported here at the American Heart Association's annual meeting and published simultaneously online in the New England Journal of Medicine.
About 13% of patients on Inspra died vs. 16% of patients given placebo. Also, 12% of patients on Inspra were hospitalized for heart failure, compared with nearly 19% of those on placebo.
Only 19 people would need to be treated for one year to prevent one death due to heart disease or heart failure hospitalization, and 51 to prevent one death, Zannad tells WebMD.
That "position[s] this therapy in the front rank of therapeutic choices," Paul W. Armstrong, MD, of the University of Alberta in Edmonton, writes in an editorial accompanying the study.
Inspra's Cheaper Cousin May Offer Option in Heart Failure
More than 5 million Americans have heart failure, which occurs when the heart muscle becomes damaged and loses its ability to pump enough blood throughout the body, often as a result of a heart attack or years of uncontrolled high blood pressure.
Fluid can back up into the lungs, leaving people gasping for breath. Fluid can also build up in other tissues, causing swelling. Inspra, made by Pfizer Inc., which funded the study, helps block water retention.
The University of Pennsylvania's Mariell Jessup, MD, head of the committee that chose which studies to highlight at the meeting, tells WebMD that the new findings have the potential to change how doctors treat people with mild heart failure.
Armstrong says that an alternative is to use Inspra's older cousin, spironolactone. It costs less than $30 a month vs. more than $130 for a 30-day supply of Inspra.
"A reasonable tactic" would be to try the older drug first and reserve the more expensive one for the few patients for whom spironolactone's side effects are disabling, he writes.
Clyde Yancy, MD, of Baylor University Medical Center in Dallas and immediate past president of the AHA, says that some patients may prefer Inspra because it doesn't cause breast enlargement in men and loss of libido in women. Spironolactone causes these side effects in about 10% of patients, he tells WebMD.
As the AHA prepares to revise its guidelines for heart failure in 2011, the new findings will be given "strong consideration," says Yancy, who heads the guidelines committee.
Currently, only about one-third of people with advanced heart failure who are candidates for Inspra or spironolactone get the drugs, he notes.
"Hopefully these findings will push more doctors to use them" in people with mild and advanced disease, unless there is a medical reason not to, Yancy says.
Potassium Levels Need to Be Monitored
The trial involved 2,737 patients 55 or older with mild heart failure. They were given either Inspra or placebo.
The study was stopped early because of Inspra's overwhelming benefits. Side effects were slightly less common in the Inspra group: 13.8% vs. 16.2% for placebo, but the difference could have been due to chance.
If you are on Inspra, your blood potassium levels need to be monitored carefully and the dose adjusted as needed, he says.
Armstrong says that although the patients had mild disease, they were at fairly high risk of complications. This may limit generalizing the findings to all patients with mild disease, he says.