Foxglove has dramatic spikes of tubeshaped flowers. The leaves are a source of digitalis, a potent heart drug.
The controversial heart failure drug has a new role in limiting hospital stays.
Dating from the 1700s, the ornamental purple foxglove (Digitalis purpurea) has been lauded for its medicinal properties. The modern-day derivative, digoxin, is among the oldest cardiac drugs still in use. And while digoxin will never again be the primary drug in heart failure treatment, it has settled into a useful niche for people with moderate to severe heart failure symptoms.
The specter of sudden death
Early in digoxin’s long history, doctors noted that digitalis extracts fortified the heartbeat and helped the body rid itself of excess fluid. They speculated, therefore, that digoxin could offset the negative effects of a weak heart muscle by increasing the heart’s pumping vigor. However, digoxin was a tricky drug to administer correctly. The higher doses needed to strengthen the heartbeat could be harmful. “In theory, the effect of increasing the strength of the heart’s contractions should be a good thing, but in practice it has been associated with poor outcomes and sudden death,” explains Dr. G. William Dec, chief of the cardiology division and professor of medicine at Harvard-affiliated Massachusetts General Hospital.
With the development of newer, safer heart failure drugs, digoxin gradually fell out of favor. But digoxin’s proponents continued to maintain that there was a role for the medication. They pointed to several studies conducted in the past decade showing that people doing well on digoxin had a 25% to 30% chance of worsening within a few weeks of stopping the drug.
Learning from the DIG study
The National Institutes of Health sought to put an end to the controversy with the Digitalis Investigation Group (DIG) trial, published in The New England Journal of Medicine in 1997. The findings left researchers scratching their heads. Digoxin neither increased nor decreased overall mortality, but it did cut down the rate of hospitalizations. An examination of the subgroups within the study revealed that the people who were receiving the standard levels of the drug were more likely to die from abnormal heart rhythms (arrhythmias). However, those who were taking what was considered a subtherapeutic dose actually had improved symptoms and didn’t appear to be at extra risk of sudden death. “It turns out that we were focusing on the wrong things,” says Dr. Dec.
Digoxin’s true benefit lies in its ability to interact with the signaling mechanism within the heart and circulatory system. The drug helps calm the cycle of excess cardiac stimulation, which is triggered when the heart is unable to pump blood effectively. In this way, digoxin is a useful adjunct to the pharmaceutical heavy hitters such as diuretics, beta blockers, vasodilators, and ACE inhibitors. “We have a drug that can improve quality of life and keep people out of the hospital. Many heart failure patients say that is a favorable trade-off. Not every heart failure drug has to improve survival,” says Dr. Dec.
Renewed interest in an old remedy
Dr. Dec cites three important reasons for the drug’s recent resurgence in popularity. First is a better understanding about the safety of the drug. With lower doses, overstimulating the heart and causing arrhythmias is less of a concern. Also, digoxin is very inexpensive compared with newer cardiac medications on the market.
Perhaps the most important driver is the current emphasis on lowering the number of hospital visits among heart failure patients. For complex reasons, being admitted to the hospital for a flare-up of heart failure complications often sets a person on a downward slide that results in another hospital stay within a couple of months. “If you can break that cycle and prevent another admission by using digoxin, that would be a good thing,” says Dr. Dec. “Lowering readmissions by even 10% or 20% would have a huge effect.”
Common heart failure symptoms
Heart failure symptoms stem from the decrease in oxygen supply to the body and the buildup of excess fluid. Warning signs of heart failure include: