Aims The purpose of this study was to evaluate the influence of left ventricular systolic function on the survival in a large consecutive cohort of patients hospitalized with congestive heart failure and to determine how left ventricular systolic function interacts with co-morbid conditions in terms of prognosis. Methods and results Analysis of survival data from 5491 patients admitted for new or worsening heart failure to 34 departments of cardiology or internal medicine in Denmark from 1993-1996 was carried out. A standardized echocardiograrn was available for 95% of the patients, and left ventricular systolic function was estimated using wall motion index score. Follow-up time was 5-8 years. Patients with preserved systolic function were older, more frequently female, and had less evidence of ischemia than patients with systolic dysfunction. After 1 year, 24% of the patients had died. Low watt motion index was a potent independent predictor of death (risk ratio for one unit increase, 0.60 (0.56-0.64)), and was of greater prognostic significance in younger patients and patients with a history of myocardial ischemia. However, even in patients with preserved systolic function, mortality was high (1 year mortality, 19%). Conclusion In hospitalized heart failure patients, particularly in younger patients with ischemic heart disease, mortality risk is inversely related to left ventricular systolic function. (C) 2003 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.