Aim To study the effectiveness of a treatment based on monitoring the soluble ST2 receptor (sST2) concentration in patients with chronic heart failure (CHF) with reduced left ventricular ejection fraction (LVEF) after acute decompensated heart failure (ADHF).Material and methods The study included 37 patients hospitalized for ADHF with LVEF ≤40% and sST2 concentration ≥37.8 ng/ml at the time of discharge from the hospital. Patients were randomized into two groups: a sST2 monitoring (sST2M) group (19 patients) and a standard therapy (ST) group (18 patients). The follow-up period was 12 months. At baseline, the groups practically did not differ by clinical, functional, laboratory, and instrumental characteristics. For the sST2M group, the goal was reducing the sST2 concentration by >30% of baseline or to <30 ng/ml.Results Therapy in both groups was comparable both in doses and in frequency of administration of basic drugs. However, the diuretic therapy was more frequently adjusted in the sST2M group (3.0 [1.0; 4.0] vs. 1.0 [0; 3.0] adjustments per patient, p = 0.047), which required more visits to the clinic (7.0 [6.0; 9.0] vs. 6.0 [6.0; 6.0] visits per patient, p=0.024). In the sST2M group at 6 months, the sST2 concentration was decreased by 43.3% (p=0.001), and 13 patients (72.2%) achieved the goal. In the ST group, the sST2 concentration was decreased by 38.5% (p=0.001), and 11 patients (68.8%) reached the target values. After 12 months, the downward trend continued in both groups. In both groups, the NT-proBNP concentration decreased: in the sST2M group by 27.7% (p=0.014), and in the ST group by 31.9% (p = 0.006). By the 12th month, the decrease remained only in the sST2M group. Only the sST2M group had an increase in LVEF (+28.5%, p=0.003), a decrease in left ventricular end-systolic volume (LVESV) (-12.0%, p=0.017), and a decrease in left atrial volume (-13.4%, p=0.045); at 12 months, LVEF remained increased (26%, p=0.006), and LA volume remained decreased (-14.3%, p=0.028). Quality of life and results of 6-minute walk test (6MWT) improved in both groups. For 6 months of treatment, the sST2M group had a significantly lower incidence of composite endpoints (CEP, cardiovascular death and decompensation/hospitalization due to HF), 26.3% (5 events) of the sST2M group compared to the ST group, 83.3% (15 events) (p=0.029), primarily due to a lower incidence of decompensated HF. For 12 months of follow-up, the incidence of CEP in the ST group was 122.2% (22 events), and 47.4% (9 events) in the sST2M group (p=0.035).Conclusions The tactics of sST2 monitoring used in the treatment of "high-risk" HFrEF patients (with high sST2 concentrations) is associated with increased LVEF, improved functional status of patients, a beneficial effect on LV remodeling, and decreased incidence of CEP.