The importance of whether atrial fibrillation or heart failure develops first

Atrial fibrillation (AF) and heart failure often co-exist. It is unknown whether the sequence in which AF and heart failure develop is of significance regarding prognosis. We assessed the prognosis of AF patients hospitalized for heart failure based on the timing of AF and heart failure development. Consecutive AF patients hospitalized for heart failure were included. Patients who had developed AF before or consecutively with heart failure (oAF first') were compared with patients who had developed heart failure before AF (oheart failure first'). The primary endpoint was a composite of cardiovascular hospitalization or all-cause mortality. The majority of patients hospitalized for AF and heart failure consisted of patients who had developed AF first (137 of 182 patients, 75, vs. 45 of 182 patients, 25). The two groups were similar regarding age and gender, but patients with AF first less often had coronary artery disease and had higher ejection fractions than patients with heart failure first (39 14 vs. 32 13, P 0.004). During 16 11 months follow-up, the primary composite endpoint occurred less often in patients with AF first than in patients with heart failure first (49.6 vs. 77.7 of patients, P 0.001). Development of AF first remained beneficial regarding the primary endpoint on multivariable analysis (adjusted hazard ratio 0.50, 95 confidence interval 0.290.86, P 0.01). The majority of patients hospitalized for AF and heart failure consisted of patients who had developed AF first. Prognosis in these patients was relatively benign as compared with those who had developed heart failure first.