Background: Atrial fibrillation occurs commonly in heart failure; however, its importance in terms of prognosis is controversial.
Methods and results: We assessed the relation of atrial fibrillation on first Holter monitor to morbidity and mortality in mild to moderate heart failure in 632 patients in the Veterans Affairs Vasodilator-Heart Failure Trial (V-HeFT) I and 795 patients in V-HeFT II: Ninety-nine patients in atrial fibrillation and 533 patients in sinus rhythm were followed for a mean of 2.5 years (range, 6 months to 5.7 years) in V-HeFT I; 107 patients in atrial fibrillation and 688 patients in sinus rhythm in V-HeFT II were followed for a mean of 2.5 years (range, 6 months to 5.0 years). V-HeFT I compared treatment with prazosin, hydralazine-isosorbide dinitrate, and placebo, whereas V-HeFT II compared hydralazine-isosorbide dinitrate with enalapril. Follow-up evaluations included serial Holter monitors, serial metabolic exercise testing, hospitalization data, and clinical examinations. In V-HeFT I, cumulative mortality at 2 years was 0.34 for patients with atrial fibrillation and 0.30 for patients in sinus rhythm (p = 0.25). Overall cumulative mortality was 0.54 for atrial fibrillation patients and 0.64 for sinus rhythm patients (p = 0.86). In V-HeFT II, cumulative mortality at 2 years was 0.20 for patients with atrial fibrillation and 0.21 for patients with sinus rhythm (p = 0.68), and overall cumulative mortality was 0.46 for atrial fibrillation patients and 0.52 for those in sinus rhythm (p < 0.46). Sudden death was not increased with atrial fibrillation in V-HeFT I patients (p = 0.64) or in V-HeFT II (p = 0.68). By multivariate analysis, the relative mortality risk for atrial fibrillation was 0.95 in V-HeFT I and 0.76 in V-HeFT II: Metabolic exercise testing, showed no significant difference in mean change in peak oxygen consumption between patients with atrial fibrillation and those with sinus rhythm in V-HeFT I and a slight decrease late in V-HeFT II: Hospitalization rate for heart failure was not increased in either study. The embolic event rate was not increased for atrial fibrillation patients: 3% versus 4.9% of patients in sinus rhythm (p = 0.41) in V-HeFT I and 4.0% versus 6.0% in V-HeFT II patients (p = 0.44). A secondary analysis compared mortality of patients in atrial fibrillation with that of patients in sinus rhythm on all Holters: Mortality was not increased overall (p = 0.72 in V-HeFT I and p = 0.35 in V-HeFT II).
Conclusions: Atrial fibrillation does not increase major morbidity or mortality in mild to moderate heart failure.