Treating viral heart infections

NEW ORLEANS — A viral infection of the heart can be eliminated or at least slowed by treatment with the drug interferon, a team of European researchers reports. Viral infections show up in some patients with heart failure and may bear some responsibility for the condition, particularly when it shows up in young or middle-age patients.

Although the new results are preliminary, many patients reported feeling better, cardiologist Heinz-Peter Schultheiss of Charité – Universitätsmedizin Berlin reported November 11 at the American Heart Association’s annual Scientific Sessions meeting.

The findings also suggest yet another role for interferon, a multipurpose drug that, in slightly different forms, is used against the hepatitis C virus and multiple sclerosis.

Heart failure is a catch-all diagnosis for a decline in heart function that can’t be directly attributed to a heart attack. It typically shows up as a shortness of breath and a weakened ability of the heart to pump blood. But it can have few outward symptoms.

Heart failure is the leading cause of hospitalization among elderly people. More than 80 percent of heart failure cases result from atherosclerosis (clogging and stiffening of the arteries) or high blood pressure or both, says Robert Bonow, a cardiologist at the Feinberg School of Medicine, Northwestern University in Chicago. Beyond that, its causes are less clear. A common form of heart failure is cardiomyopathy, in which the heart muscle becomes inflamed and the heart functions poorly. Cardiomyopathy is a frequent reason for getting a heart transplant.

In the new study, the researchers biopsied heart tissue in 368 people with cardiomyopathy and found that more than two-thirds had a viral infection in the heart. The scientists then randomly assigned 95 of these people to receive injections of the drug interferon beta-1b every other day for six months. Another 47 received placebo injections over that time.

Three months after the last shot, a second round of heart biopsies showed that the interferon recipients were more than twice as likely to have reduced the presence of or cleared the virus from the heart, compared with those getting the placebo, Schultheiss reported.

Although follow-up heart biopsies taken six months after the end of treatment showed no statistically significant difference in viral concentration between the groups, other assessments made during that time frame suggest that the gains were still holding. For example, interviews with the patients showed that those getting interferon reported a higher quality of life than the placebo recipients. And other tests indicated that the interferon group scored higher on measures of everyday activities, compared with those who had gotten the placebo.

Several viruses that normally cause common colds or respiratory infections have been found to set up shop in the heart, including adenovirus, parvovirus and enterovirus. Whether these viruses directly cause heart inflammation in people with cardiomyopathy remains unclear, which makes studies such as the new one valuable, says Michael Felker, a cardiologist at Duke University School of Medicine in Durham, N.C.

Only in the past decade have scientists developed the techniques to identify patients with such viral infections and the virus involved, he says. But those techniques require a biopsy. Short of that, it’s impossible to know who has a viral heart infection. Bonow says that’s why it’s not clear what percentage of heart failure patients might fall into this category.

Although the new findings are promising, he says, obstacles remain. The downsides of getting a heart biopsy are obvious. And interferon treatment, in the form of a subcutaneous injection given every other day, is a lot to bear. Deciding which heart failure patients with cardiomyopathy would be likely to benefit from either the test or the treatment might require some calculation, Bonow says. “Maybe we would choose a certain age group, or people who don’t have underlying coronary disease.”

Interferon therapies are based on natural proteins that have antiviral and immune-modulating roles in the body. When used in drug form, they duplicate some of these roles, though their mode of action is poorly understood.

Interferon therapy can cause some side effects and is expensive — about $10,000 for the six-month treatment.

Further studies may clarify whether spending that kind of money yields results that are worthwhile, Felker says. “But theoretically, if you prevent the progression of worse heart failure — and the need for a heart transplant — you can imagine that even a pretty expensive therapy could be cost-effective,” he says.