Aim To analyze long-term outcomes by results of the prospective part of the Kuban registry of patients with an implantable cardioverter defibrillator (ICD).Material and methods A prospective analysis of the incidence of hard endpoints and changes in the condition was performed for 260 patients with ICD successively added to the Registry of Patients with Implantable Cardioverter Defibrillator" from 2015 through 2019.Results At the time of ICD implantation, all patients had chronic heart failure (CHF), mostly of ischemic etiology with a low left ventricular ejection fraction (LVEF); median LVEF was 30 (25; 36.5) %. 54 of 266 (21.9 %) patients died by 2021; 17 of them (31.5 %) died in the hospital; in 76.5 % of cases, death was caused by acute decompensated heart failure (HF). 139 (53.5%) patients were readmitted; 66 (25.4 %) hospitalizations were related with ICDs (lead revision or reimplantation); acute cardiovascular events developed in 38 (14.6 %) patients; 12 (4.6%) patients underwent percutaneous coronary interventions; orthotopic heart transplantation was performed for 4 patients. ICD shocks were recorded in 27 (10.4 %) patients. After the ICD implantation, median LVEF remained unchanged, 31 (25; 42) vs. 30 (25; 36.5) % (р>0.05). However, both objective and subjective HF symptoms worsened. Thus, the number of patients with IIB stage CHF increased from 29.6 to 88.8 % (р<0.01) and with NYHA III CHF from 24.2 to 34.5 % (p<0.05). 80 (30.8%) patients visited cardiologists on a regular basis. Only 7.3% of patients received an optimal drug therapy. During the observation period, the rate of beta-blocker treatment considerably decreased, from 90.6 to 64.3 % (р<0.01), and the rate of the mineralocorticoid receptor antagonist treatment decreased from 50.8 to 17.4 % (р<0.01). The rate of the diuretic treatment was inconsistent with the severity of patients' condition.Conclusion Most of the problems the patients encountered after the ICD implantation were related with an inadequate treatment of the underlying disease. Since the majority of patients with ICD have a low LVEF, it is essential to focus on prescribing an optimal drug therapy and maintaining compliance with this therapy.