Digoxin in atrial fibrillation: report from the Stockholm Cohort study of Atrial Fibrillation (SCAF).

BACKGROUND: Recent studies of patients with heart failure and of patients receiving intensive care indicate that digoxin may increase mortality if the patient has atrial fibrillation (AF). Objective To study which patients receive digoxin treatment for AF and what the prognosis is for patients given this treatment.

METHOD: 2824 patients with AF were studied prospectively for a mean of 4.6 years. Information about medication was obtained 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: Factors associated with digoxin use were permanent AF (hazard ratio (HR) = 3.2, confidence interval (CI) 2.7 to 3.9), absence of pacemaker (HR = 2.3, CI 1.6 to 3.2), history of heart failure (HR = 2.0, CI 1.7 to 2.5), treatment in an internal medicine ward rather than a cardiology ward (HR = 1.6, CI 1.3 to 2.0), female sex (HR = 1.6, CI 1.3 to 1.9) and age >or=80 years (HR = 1.4, CI 1.1 to 1.7). More patients with than without digoxin died (51% vs 31%, p<0.001). After adjustment for covariates, however, no disadvantages related to digoxin use could be found for all-cause mortality, myocardial infarction, ischaemic stroke, time to readmission to hospital or days at hospital/year at risk. The only end point significantly associated with digoxin use was pacemaker implantations, which were more common in digoxin-treated patients (HR = 2.0, CI 1.2 to 3.4).

CONCLUSION: Digoxin is mainly given to an elderly and frailer subset of patients with AF and is thus associated with an increased mortality. When differences in patient characteristics are accounted for digoxin use seems to have a neutral effect on mortality and major cardiovascular events in patients with AF.