Study shows heart drug digitalis safe in patients with diastolic heart failure

Jul 26 2006

Despite a widely held belief that the heart drug digitalis shouldn't be given to patients with diastolic heart failure, a new analysis shows it is relatively safe.

"Contrary to conventional wisdom, digitalis did not have an overall detrimental effect. The study advances our understanding of both digitalis, the oldest known heart medicine, and of diastolic heart failure, the newest form of heart failure," said Dalane Kitzman, M.D., a professor of cardiology at Wake Forest University School of Medicine and a co-author on the report, published on-line in the journal Circulation.

Kitzman said the study, which involved 988 patients, is significant because it is one of the first to evaluate a treatment for diastolic heart failure, the most common type in older adults, which is expected to increase as the population ages.

There are an estimated 5 million heart failure patients in the United States, and about half have diastolic heart failure, in which the heart muscle is stiff and doesn't take in enough blood with each beat. The other type, systolic heart failure, is when the heart muscle is too weak to effectively pump blood out into the body.

In systolic heart failure, digitalis has been shown to have a number of benefits, including improving symptoms, quality of life, exercise tolerance, heart muscle contraction, and controlling atrial fibrillation, the most common heart rhythm abnormality in heart failure.

"However, its use in diastolic heart failure has been discouraged due to concerns based on small, anecdotal studies that it might precipitate early death," said Kitzman. "Our findings that it is relatively safe in this disorder allow it to be prescribed if needed for atrial fibrillation, and to be evaluated further to see if it has other benefits, such as improving symptoms, as it does for systolic heart failure."

Few drugs for diastolic heart failure have been tested in randomized studies of patients - largely because it wasn't recognized as a separate form of heart failure until more recently. "There are few evidenced-based recommendations for these patients," wrote the authors.

The results reported in Circulation are from a larger study conducted in the United States and Canada from 1991 to 1993 and had not been previously published.

The study involved patients with diastolic heart failure who were assigned to receive either digitalis, also known as digoxin, or a placebo. Digitalis slows the heart rate, helps eliminate fluid from body tissues, and strengthens the contraction of the heart muscle. Most patients were also receiving two common treatments for heart failure: diuretics and angiotensin-converting enzyme inhibitors.

Patients were followed for a mean of 37 months. The team of researchers, from 10 different medical centers, analyzed data from the study and found that digitalis had no effect on death from heart failure or any cause, or on hospitalizations related to heart failure or any cause.

There was a trend, which wasn't strong enough for researchers to know if it occurred by chance or was associated with use of digitalis, for patients to have reduced hospitalizations from worsening heart failure, but there was also a trend of increased hospitalizations for unstable angina.

The lead author on the report is Ali Ahmed, M.D., M.P.H., from the University of Alabama at Birmingham. Senior author is Mihai Gheorghiade, M.D., from Northwestern University.

"These results are somewhat of a paradigm shift," said Kitzman. "They show that although digitalis has no definite significant net benefit for diastolic heart failure, it also does no net harm. There is no need to avoid prescribing it, such as for atrial fibrillation, though other newer drugs are often used first."