Low-Dose Digoxin Shows Renewed Promise in Heart Failure

Why Are Researchers Revisiting Digoxin for Heart Failure?

Digoxin, derived from the foxglove plant, has been used in cardiac medicine for more than two centuries and was a mainstay of heart failure treatment for decades. The landmark Digitalis Investigation Group (DIG) trial, published in The New England Journal of Medicine in 1997, found that digoxin did not reduce all-cause mortality in patients with heart failure but did reduce hospitalizations. Since then, the drug has been progressively displaced by therapies with stronger mortality benefits, including ACE inhibitors, angiotensin receptor-neprilysin inhibitors (ARNIs), beta-blockers, mineralocorticoid receptor antagonists (MRAs), and SGLT2 inhibitors.

The new trial published in Nature Medicine asks a clinically important question: in an era of optimized quadruple therapy, does low-dose digoxin still have a role for patients with heart failure with reduced ejection fraction (HFrEF) and the more recently defined mildly reduced ejection fraction (HFmrEF) category? Digoxin's narrow therapeutic index and historical concerns about toxicity at higher serum levels have driven interest in carefully dosed regimens that aim to preserve potential benefits on symptoms and hospitalization while minimizing harm.

How Does Low-Dose Digoxin Work in the Failing Heart?

Digoxin's primary pharmacological action is inhibition of the Na+/K+-ATPase enzyme in cardiac myocytes. This raises intracellular sodium, which in turn increases intracellular calcium via the sodium-calcium exchanger, enhancing myocardial contractility — the classic positive inotropic effect. At the lower serum concentrations now favored in clinical practice (generally under 1.0 ng/mL), neurohormonal effects are thought to predominate, including reduced sympathetic activity and improved baroreceptor sensitivity.

Modern heart failure guidelines from the European Society of Cardiology and the American Heart Association/American College of Cardiology continue to list digoxin as a possible adjunct in selected symptomatic HFrEF patients, particularly those who remain symptomatic despite guideline-directed medical therapy or who have concomitant atrial fibrillation requiring rate control. The new randomized data may help refine which patients are most likely to benefit and provide updated evidence on safety in patients already taking SGLT2 inhibitors and ARNIs, neither of which existed when the original DIG trial was conducted.

What Does This Mean for Clinical Practice?

Heart failure remains a major global health burden. According to the World Health Organization and national cardiovascular societies, heart failure affects an estimated 64 million people worldwide and is associated with frequent hospitalization, reduced quality of life, and high mortality. Even with modern quadruple therapy, many patients remain symptomatic, and access to newer agents such as ARNIs and SGLT2 inhibitors is uneven globally due to cost and availability.

Digoxin, by contrast, is widely available as a generic medication at low cost, making any confirmed benefit potentially impactful for global cardiovascular care. Clinicians considering digoxin still need to monitor for toxicity, particularly in older adults, patients with reduced kidney function, and those on interacting medications such as amiodarone or verapamil. The new trial data are likely to inform updated guidance on serum level targets, patient selection, and integration with contemporary heart failure regimens.