Background: Atrial fibrillation (AF) frequently coexists with heart failure (HF).

Aim: To assess clinical characteristics and to identify predictors of one-year outcome of patients hospitalised for HF, depending on whether they were in sinus rhythm (SR) or had AF.

Methods: The study included Polish patients hospitalised for HF, participating in the Heart Failure Pilot Survey of the European Society of Cardiology, who were followed for 12 months after discharge. Patients with paced heart rhythm were excluded from the study. The primary endpoint was all-cause death at 12 months.

Results: The final analysis included 587 patients. AF occurred in 215 (36.6%) patients. Compared to patients in SR, patients with AF were older, more often had a history of previous HF hospitalisation, were characterised by a higher New York Heart Association (NYHA) class, higher heart rate, and lower diastolic blood pressure at hospital admission, and had higher serum creatinine and lower haemoglobin concentration at admission. In-hospital mortality was higher in AF patients compared to SR patients (5.1% vs. 2.4%, respectively), but the difference did not reach statistical significance (p = 0.1). The primary endpoint occurred in 41 of 215 AF patients (19.1%) and in 40 of 372 SR patients (10.8%; p = 0.006). In a multivariate analysis, predic­tors of the primary endpoint in AF patients were: higher NYHA class at hospital admission (p = 0.02), higher admission heart rate (p = 0.04), lower admission serum sodium concentration (p = 0.0001), and higher heart rate at discharge (p = 0.01). In patients with SR, independent predictors of the primary endpoint included: older age (p = 0.007), lower serum sodium concentration at admission (p = 0.0006), and higher heart rate at discharge (p = 0.008).

Conclusions: Patients with HF and concomitant AF differ significantly from HF patients in SR. In the studied group of real-world HF patients, serum sodium concentration at hospital admission and heart rate at hospital discharge were independent prog­nostic factors in patients with AF and in patients in SR. In contrast to SR patients, heart rate at hospital admission in AF patients was also predictive of long-term mortality.