Scientists have found that the drug, allopurinol, can make heart muscle run better while using less energy when it's infused directly into the organ's blood supply.
Experts caution, however, that with only nine patients, the study's quite small, and that infusing the heart isn't an appropriate way to treat large numbers of people.But, they add, the results are encouraging enough to warrant additional research into the drug as a possible therapy for heart failure, a disease with no cure that strikes 550,000 Americans a year.
Dr. Rose Marie Robertson, immediate past president of the American Heart Association and a professor of medicine at Vanderbilt University Medical Center in Nashville, Tenn., calls the new work "an interesting study from an excellent laboratory."
Robertson says that, although the report is still merely proof of a principle, allopurinol "had a positive effect, and the positive effect was quite uniform. This wasn't a fluke."
Gout, called the "disease of kings and the king of diseases," is caused by the buildup of uric acid in the blood. It can become painful when crystalline deposits of the compound form in the joints and lead to arthritis.
Allopurinol is a leading gout therapy that inhibits xanthine oxidase (XO), an enzyme that helps cells process energy. The formation of xanthine is an intermediate step in the production of uric acid, so interrupting the process can prevent uric acid crystals from forming in the joints.
For reasons that aren't understood, XO is also overactive in heart failure patients, and its presence could signal oxidative damage to vessels.
Heart failure sets in when the organ can't deliver adequate blood to the rest of the body. As the struggling heart falters, its energy demands increase while its pumping ability flags. Patients with congestive heart failure suffer debilitating accumulation of fluid in their lungs and elsewhere.
In the new study, which appears this week in Circulation: Journal of the American Heart Association, Dr. Thomas Cappola of Johns Hopkins University and his colleagues wondered if they could improve pump function in heart failure patients by blocking XO.
Cappola's group infused varying doses of allopurinol directly into the heart muscle of seven men and two women who had a form of congestive heart failure called dilated cardiomyopathy, in which the left ventricle becomes bloated and weak.
When the patients, who were also taking other routine cardiac drugs, received the infusion for 45 minutes, their heart muscle consumed about 16 percent less oxygen at little cost to its pumping power, the researchers found. Overall, the drug led to short-term gains of between 22 percent and 40 percent in heart efficiency at the middle dose of the drug -- roughly equal to what a gout patient would take.
Dr. Joshua Hare, a Hopkins cardiologist and co-author of the study, says the findings are particularly encouraging because no treatments to date have managed to boost heart efficiency, which drops by between 50 percent and 75 percent in heart failure patients.
"It makes a lot of intuitive sense that improving efficiency would be good for patients. But we've had a lot of theories that made intuitive sense that didn't translate into benefits for patients," he adds.
Hare, director of the university's heart failure research program, says an earlier study in dogs returned even better results, probably because the animals weren't taking other medications, as were the patients in the latest trial.
The Hopkins team is now trying to organize a follow-up study to test a pill form of allopurinol in heart failure patients.
What To Do
For more on gout, try the American College of Rheumatology.