Background: Currently, one of the most common causes of hospitalization, especially in the elderly,
is heart failure (HF) exacerbation. In nearly 95% of patients, this is caused by fluid overload. There
have been studies comparing the rates of comorbidities and biochemical disturbances in HF patients;
however, their hemodynamic parameters have not yet been assessed. Thus, the aim of this study
was to compare the clinical presentations and hemodynamic parameters assessed via impedance
cardiography (ICG) in patients hospitalized due to acute HF, stratified by the left-ventricular ejection
fraction (LVEF).

Methods: This study enrolled 102 patients, aged > 18 years, hospitalized due to decompensated HF.
Ninety-seven patients (74 men, 23 women) underwent echocardiographic examination. Biochemical
and hemodynamic parameters were assessed on the day of admission and, subsequently, every
other day during hospitalization. Based on echocardiographic findings and the ESC guidelines the
study group was divided into the following subgroups: HFrEF (EF < 40%), HFpEF (EF > 50%), and
HFmrEF (EF 40–49%).

Results: The HFrEF group, which constituted 60.8% of patients (n = 58), was predominantly male (P =
0.0005); and most had elevated N-terminal pro-brain natriuretic peptide levels (P = 0.0008). The HFpEF and
HFmrEF subgroups, jointly (n = 38), were characterized by higher systolic blood pressure (P = 0.0001),
and lower hemoglobin levels (P = 0.003). The hemodynamic assessment showed that HFrEF patients
had higher total fluid content (P = 0.005) and lower systolic time ratio (P = 0.0002).

Conclusions: Despite similar clinical presentation, patients with HF exhibited different values of hemodynamic
and biochemical parameters depending on their LVEF; this indicates non-homogeneity of pathomechanisms
and causes of HF decompensation.