WASHINGTON (FRONTLINE MEDICAL NEWS) – The use of digoxin by Swedish Heart Failure Registry participants with heart failure with reduced ejection fraction was associated with significantly increased risk of all-cause mortality if they had concomitant paroxysmal atrial fibrillation or were in normal sinus rhythm, Gianluigi Savarese, MD, reported at the annual meeting of the American College of Cardiology.

In contrast, digoxin in Swedish patients with heart failure with reduced ejection fraction (HFrEF) and permanent atrial fibrillation (AF) was associated with a reduced risk of heart failure hospitalization but had no impact on mortality, added Dr. Savarese of the Karolinska Institute in Stockholm.

The Swedish Heart Failure Registry includes the majority of heart failure patients in that country. Data on 80 variables gets collected for each participant.

Dr. Savarese reported on 23,708 Swedes with HFrEF, 18% of whom were on digoxin. In a multivariate Cox regression analysis adjusted for numerous potential confounders, the use of digoxin was associated with an 8% increased risk of all-cause mortality and a 10% lower risk of heart failure hospitalizations during up to 11 years of follow-up.

In the 12,162 patients with HFrEF and comorbid AF, 30% of whom were on digoxin, the drug was associated with a 12% reduction in heart failure hospitalizations and had no effect on all-cause mortality.

In contrast, among patients with HFrEF without AF, 5% of whom were taking digoxin, use of the drug was associated with an adjusted 31% increase in mortality risk. But digoxin didn’t affect the risk of heart failure hospitalization one way or the other in this group.

Stratifying subjects by their type of AF, the use of digoxin in patients with HFrEF and permanent AF was associated with a 16% reduction in risk of heart failure hospitalization with no impact on mortality. In contrast, among the 2,723 patients with HFrEF and paroxysmal AF, digoxin was associated with a 29% increase in the risk of mortality and no effect on hospitalization.

Current ACC/American Heart Association heart failure guidelines give digoxin a strong Class IIa recommendation for reducing heart failure hospitalizations in patients with HFrEF. European Society of Cardiology guidelines provide a Class IIb recommendation for digoxin to reduce the risk of hospitalization in patients with symptomatic HFrEF in normal sinus rhythm.

Dr. Savarese said he and his coinvestigators decided to examine the impact of digoxin in the Swedish Heart Failure Registry because despite the guideline support for the drug’s use, recent years have brought conflicting data regarding digoxin’s impact on mortality. For example, a meta-analysis of nine studies in more than 235,000 AF patients, seven studies in patients with heart failure, and three in patients with both disorders showed that digoxin was associated with a 29% increased mortality risk in AF patients and a 14% increase in those with heart failure ( Eur Heart J. 2015 Jul 21;36[28]:1831-8 ).

Moreover, at a late-breaking clinical trial session elsewhere at ACC 17, a secondary analysis of the roughly 18,000-patient ARISTOTLE trial came down emphatically on the side of avoiding the venerable drug in patients with AF, where it was found to be associated with a fourfold increased risk of sudden death.

Session comoderator Lee R. Goldberg, MD , medical director of the University of Pennsylvania Heart Failure and Transplantation Program in Philadelphia, observed that the use of digoxin has become quite controversial. He posed a question to Dr. Savarese: “Every few months someone writes the last paper on digoxin as they look at thousands of patients, and then there’s always a new paper. If you were to rewrite the guidelines now, what would you recommend for digoxin?”

Dr. Savarese replied that the current guidelines rely heavily upon the results of a 20-year-old randomized, double-blind, placebo-controlled trial of digoxin in heart failure ( N Engl J Med. 1997 Feb 20;336[8]:525-33 ). Those study participants look nothing at all like the heart failure patients physicians see today in clinical practice. Hardly any of them were on what today is guideline-directed medical therapy with a beta-blocker or mineralocorticoid receptor antagonist. So the trial’s applicability is dubious.

“Our Swedish data are observational. They are hypothesis-generating. They should drive trialists to design a new trial of digoxin. But I think we all know that’s not going to happen. So actually I don’t think there is still space for a IIb or IIa recommendation for digoxin in the guidelines,” Dr. Savarese said.

He reported having no financial conflicts.