INTRODUCTION
Acute heart failure (AHF) is the final consequence of a large number of cardiovascular diseases and is one of the most important health care problems in developed countries. The prevalence of AHF is increasing with the aging of the population1. This disease causes relevant mordibity and mortality and is among the main causes of hospitalization, hospital mortality and health care costs in Spain2,3,4,5, with most hospital admissions being made through hospital emergency departments (HEDs)6,7,8,9.
Although the role of anemia as a triggering factor of cardiac decompensation is well known10, in the last years the study of anemia in patients with heart failure (HF) has become the focus of increasing interest due to its elevated prevalence and prognostic implications. HF has been described as being associated with greater hospitalization and with an increase in mortality in patients with a reduced and preserved ejection fraction11. The prevalence of HF varies widely in the different studies available, ranging from 4 to 55%, with one third of the patients presenting decompensated HF12,13.This variability can be explained by the different study populations selected and by the absence of consensus in relation to the definition of anemia in the different studies14, although when using the criteria of the World Health Organization (WHO) (hemoglobin [Hb] < 12 g/dl in women and < 13 g/dl in men), the prevalence is 30 % in stable patients and 50% in decompensated hospitalized patients15.
The cause of anemia in patients with HF is probably multifactorial. Different mechanisms have been described16: reduction in intestinal iron absorption, increase in cytosines, activation of the renin-angiotensin-aldosterone system, renal dysfunction due to vasoconstriction and renal ischemia and loss of erythropoietin and transferrin by the coexistence of proteinuria and hematic losses related to antiaggregant or anticoagulant treatments.
Multiple observational studies have found that the presence of anemia conditions a worse prognosis in patients with HF17, in terms of mortality and readmission due to decompensation of HF. Data on the impact of anemia on mortality in patients with AHF are scarce, and the studies available are retrospective and usually include patients who are hospitalized in conventional hospital wards. In a recent study including 756 patients admitted for AHF, it was observed that Hb values < 10 g/dL were significantly related to a greater mortality at 3 years, greater readmission at 30 days and longer hospital stay18.
It has been reported that the use of iron and erythropoietin may be beneficial in these patients. Silverberg and col19demonstrated that this treatment improved the ventricular ejection fraction and functional capacity in a group of refractory HF patients. The beneficial effect of the correction of anemia in this group of patients was translated into a better quality of life, functional capacity and lower rate of readmissions.
It is still not clear whether the association between anemia and the outcomes of patients with AHF is causal or anemia is a marker of risk. The favorable results of studies on the treatment of anemia together with the harmful hemodynamic effects and the possibilty that it favors myocardial ischemia support a cause-effect relationship. Therefore, the main aim of this study was to evaluate the effect of anemia on short-term mortality (30 days) and at one year in patients with AHF and determine the implication of anemia in progressive mortality from patient inclusion until one year of follow-up.