Scientists have questioned whether atrial fibrillation patients should be treated with the heart drug digoxin after new evidence suggests that it increases death rates.
A study of more than 122,000 Americans with an abnormal heart rhythm showed that those given digoxin were 20% more likely to die than patients receiving different treatments.
It follows another US trial two years ago, involving 4,000 atrial fibrillation patients, that associated digoxin treatment with a 41% increase in deaths.
Digoxin is derived from the poisonous foxglove plant, also known as digitalis, which has been used to treat heart conditions since the 18th century.
The drug, which slows heart rate and increases the force of heart contractions, is widely prescribed for heart failure and rhythm disorders.
In the latest study, US researchers analysed the records of 122,465 patients diagnosed with atrial fibrillation between 2003 and 2008.
Doctors prescribed digoxin to 23% of the patients, 70% of whom were still taking it one year later.
“The take-home point is to question whether people should really be on this drug”
They were 1.2 times (20%) more likely to die than similar patients on other therapies, regardless of age, the use of other drugs, or conditions such as kidney disease, heart attack or heart failure.
Lead researcher Dr Mintu Turakhia, from the Stanford University Medical Center, said: “The take-home point is to question whether people should really be on this drug. These data challenge the current guidelines.”
He stressed that pharmaceutical companies lacked the motivation to fund studies on long-accepted generic drugs such as digoxin.
“This is going to be as close to proof positive as we get because we may never have a randomised trial of this drug,” said Dr Turakhia, whose research is published online in the Journal of the American College of Cardiology.
Many other drugs were available to treat atrial fibrillation, he pointed out, adding that while digoxin slows heart rate, it does not correct an irregular heart beat.
“We are not asserting this drug should never be used,” said Dr Turakhia. “However, in light of the many other drugs that can be used to slow down the heart rate in atrial fibrillation, patients and providers need to ask whether digoxin should be the treatment of choice when there are other, safer drugs.”
The previous study, published in the European Heart Journal, reported a 41% increase in deaths from any cause in atrial fibrillation patients prescribed digoxin.
It also linked the drug to a 35% higher rate of deaths from cardiovascular disease and a 61% increased in deaths from irregular heart rhythms other than atrial fibrillation.