Background: Heart failure (HF) is a chronic disease with poor prognosis, being the final stage of many cardiovascular conditions and often requiring hospitalisation.

Aim: The aim of the study was to evaluate the effect of hospitalisation length on prognosis in patients with HF.

Methods: Between February 2012 and January 2013, in 32 cardiology centres in Poland, 1126 HF patients were included in the EURObservational Research Programme on Heart Failure Registry. A total of 765 persons were hospitalised. A follow-up (FU) of 414 ± 121 days was conducted.

Results: The median length of hospitalisation was seven days (interquartiles 25th–75th; 4–11), also for new onset (14.5% of patients) and chronic HF (seven days, 5–11 and 4–11, respectively). Patients who died during FU (16.5%) and those who survived were hospitalised for a median of eight days (6–12) and seven days (4–10), respectively (p < 0.001). Patients hospitalised for 8–21 and 22 or more days had an increased risk of death after discharge (hazard ratio [HR] 1.70; 95% confidence interval [CI] 1.16–2.49 and HR 2.20; 95% CI 1.04–4.67, respectively) than those hospitalised for up to seven days. Predictors of death in the FU period in multivariate analysis included age (1.02; 95% CI 1.01–1.04), history of chronic kidney disease (CKD) (HR 1.55; 95% CI 1.05–2.30), and New York Heart Association (NYHA) class III (HR 2.52; 95% CI 1.22–5.18) and IV (HR 4.77; 95% CI 2.32–9.82) at admission. Patients hospitalised for 22 or more days were more often male (77%), and with a history of CKD (34%). At admission they had lower systolic (118 ± 25 mm Hg) and diastolic (72 ± 12 mm Hg) blood pressure, higher NT-proBNP (9191 ± 8776 pg/mL), lower serum sodium level (137 ± 5 mmol/l), as well as lower ejection fraction before and during hospital stay (30 ± 12% and 34 ± 14%, respectively; p < 0.05 for all factors). Factors that influenced the length of hospital stay included history of CKD (p < 0.001), current malignancy (p = 0.026), and infection at admission (p < 0.001). Most of the admitted patients presented NYHA class III (45%). The poorer the NYHA class at admission, the longer the patient’s hospital stay (p < 0.001). 54% patients were re-admitted to the hospital during FU. Patients re-admitted and not re-admitted during the one-year FU had the same median duration of the index hospitalisation (seven days; 4–10 and 4–11, respectively; p = 0.957).

Conclusions: Patients with HF hospitalised for 22 or more days, in comparison to patients hospitalised for less than eight days, had double the risk of death during FU. We believe that prolonged hospitalisation might be regarded as a marker of poor prognosis in patients with acute HF.