Is Digoxin Still Useful in Heart Disease?

For over 200 years, digitalis (a substance derived from the foxglove plant), has been a mainstay in the treatment of heart disease—most specifically, heart failure and atrial fibrillation. Digoxin, by far the most commonly used form of digitalis, is still widely prescribed for the treatment of these cardiac conditions.

You might still be taking digoxin if you were prescribed this medication many years ago, or your healthcare provider might prescribe it for you if newer treatment options are not considered beneficial for your condition.

In recent decades, digoxin has been prescribed less often than in the past because:

• The benefits of several newer drugs have been proven in clinical trials, whereas there have been relatively few randomized trials demonstrating the benefits of digoxin.
• Digitalis toxicity can be difficult to avoid and can be quite dangerous. There is less potential for toxicity with newer drugs.

Despite these concerns, digoxin can still be useful for the treatment of certain heart conditions.

How Digoxin Works

Digoxin has two major mechanisms of action that can help in the treatment of heart failure or atrial fibrillation:

• Increasing the force of heart contractions: Digoxin inhibits certain pumps in the cardiac cell membranes, reducing the movement of sodium from the inside of cells to the outside of cells. By keeping sodium within the cells, it can help a weak heart muscle to pump a bit more effectively.
• Slowing the heart rate: Digoxin affects autonomic tone, decreasing the conduction of electrical impulses through the AV node of a heartbeat. This can slow the heart rate in people with atrial fibrillation.

Digoxin Toxicity

Digoxin can become toxic above a certain threshold in the blood. Unfortunately, the therapeutic drug levels of digoxin are not that much different than the toxic blood levels. This narrow therapeutic window can make digoxin difficult to use safely for many people. Toxicity can even occur when the blood level is considered normal.

Digoxin toxicity is more likely if you have kidney problems or hypokalemia (low potassium levels), both of which are common in people who have heart failure or who take diuretics.

The toxic effects of digoxin can lead to:

• Life-threatening cardiac arrhythmias in which the heart beats too quickly
• Severe bradycardia in which the heart beats too slowly

Digoxin can also cause a loss of appetite, nausea or vomiting, and neurological problems such as confusion and visual disturbances.

If you are prescribed digoxin, your blood levels will be measured periodically to attempt to stay within the narrow therapeutic window.

Treatment of Heart Failure

As recently as 30 years ago, digoxin (along with diuretics) was the mainstay of treatment for heart failure due to dilated cardiomyopathy. This is a form of heart failure characterized by a reduced ejection fraction.

But since that time, several new treatments have demonstrated improved efficacy in numerous randomized clinical trials. These include beta-blockers, ACE inhibitors, ARB agents, and Entresto (sacubitril + valsartan).

In addition, sometimes heart failure is treated with cardiac resynchronization therapy, a treatment that can also significantly reduce symptoms and improve survival.

Some studies have shown that for people who have dilated cardiomyopathy, digoxin can improve the symptoms of heart failure and reduce the need for hospitalization. However, unlike newer therapies, it does not improve survival.

Most experts now recommend digoxin for the treatment of heart failure only if all other treatment options fail.

• Digoxin offers no benefit if you have heart failure with a preserved ejection fraction (also known as diastolic heart failure).
• Digoxin is also not useful for stabilizing acute heart failure.

Treatment of Atrial Fibrillation

Since a rapid heart rate is a chief cause of atrial fibrillation symptoms, digoxin can be useful in providing some relief of symptoms.

However, beta-blockers and calcium channel blockers, now commonly used to treat atrial fibrillation, are more effective for controlling symptoms of atrial fibrillation. These medications slow the heart rate both at rest and during exercise, whereas digoxin slows the heart rate only at rest. If you have atrial fibrillation and exercise intolerance, digoxin will not provide relief for your exercise intolerance.

Furthermore, there is evidence that digoxin is associated with an increase in mortality (risk of death) when used to treat atrial fibrillation.

Digoxin is used with extreme caution if you have atrial fibrillation. However, your healthcare provider might consider prescribing it for you if you have persistent and significant symptoms at rest that are not relieved by a combination of beta-blockers and calcium channel blockers.

A Word From Verywell

Not long ago, digoxin was a mainstay of therapy for both heart failure and atrial fibrillation. However, in recent decades, newer drugs have proven to be more effective and safer to use.

With that said, digoxin still has its place in the treatment of these conditions. When used appropriately and under the supervision of a cardiologist, the drug may reduce symptoms and significantly improve your quality of life.