Abstract 2513: Digoxin in Atrial Fibrillation - From the Stockholm Cohort-study of Atrial Fibrillation (SCAF)

Abstract

Background: Recent studies of patients with heart failure and of patients in intensive care units indicate that digoxin may increase mortality if the patient has atrial fibrillation (AF). The applicability of these findings to common AF-patients is however unclear.

Aim: To study which patients receive digoxin treatment for AF and what the prognosis is for patients given this treatment.

Method: From the Stockholm Cohort Study on Atrial Fibrillation (SCAF) 2824 patients with AF was studied prospectively for a mean of 4.6 years. Information about medication was obatained from the local hospital registry. Information about diagnoses, hospitalisations and deaths was obtained from national registries. Propensity score matching and Cox regression was used to account for confounding.

Results: The factors most strongly associated with digoxin use at baseline were permanent AF (Hazard Ratio (HR) 3.2), absence of pacemaker, (HR 2.2), history of heart failure (HR 2.0) and treatment at an Internal Medicine ward rather than a Cardiology ward (HR1.9). Other factors significantly associated with digoxin use were female sex (HR 1.6) and age ≥80 years (1.4). The mortality rate was higher among patients with than without digoxin (51% vs. 31%, p<0.00001). However, no disadvantage related to digoxin use could be found after adjustment for covariates regarding all-cause mortality (HR 1.04, CI 0.89 –1.29), myocardial infarction (HR 0.95, CI 0.63–1.44), ischaemic stroke (0.87, CI 0.69 –1.11), time to readmission to hospital or days at hospital/year at risk. Patients with digoxin were less often hospitalized for heart failure if they belonged to the group most likely to receive digoxin. For the group as a whole there was no significant benefit to be seen. The only endpoint significantly associated with digoxin use was pace maker implantations which were more common in digoxin treated patients (HR 2.1).

Conclusion: Digoxin is mainly given to an elderly and frailer subset of AF-patients and is thus associated with an increased mortality. When these and other differences in patient characteristics are accounted for Digoxin use appears to be neutral visavi long term mortality and major cardiovascular events in AF patients.