Aim A 12-month evaluation of the potentialities of the angiotensin II receptor inhibitor olmesartan (Olme) and the angiotensin receptor and neprilysin inhibitor (ARNI) sacubitril/valsartan in patients with arterial hypertension (AH) and dyslipidemia in the dynamics of the following indicators of chronic heart failure (CHF): N-terminal pro-brain natriuretic peptide (NT-proBNP), left ventricular ejection fraction (LVEF), LV global longitudinal strain (LV GLS) in diffuse myocardial fibrosis (MF) previously diagnosed by magnetic resonance imaging (MRI).Material and methods Olmesartan medoxomil (n=56) and sacubitril/valsartan (n=63) were used for 12 months in patients with hypertension, dyslipidemia and NYHA functional class II-III CHF with mid-range LVEF (CHFmrEF). MF was diagnosed by the following MRI criteria: late gadolinium enhancement and an increased proportion of extracellular matrix (33% or more). The frequency of persisting late gadolinium enhancement and the increased proportion of extracellular matrix (33% or more) was evaluated at 12 months; changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), NT-proBNP, and LV GLS were evaluated after 3, 6, and 12 months of follow-up.Results Baseline parameters did not differ between groups. The late gadolinium enhancement and increased proportion of extracellular matrix were present at baseline in all patients of both groups (100%; p=1.0). Already at 3 months, statistically significant decreases in SBP and DBP were observed in both groups. In addition, the LV GLS monitoring showed LV GLS significantly increased in both groups after 3 months and continued changing after 6 and 12 months. The NT-proBNP concentration significantly decreased in both groups already after 3 months and continued to decrease after 6 and 12 months. At 6 and 12 months, sacubitril/valsartan was superior to olmesartan in reducing SBP and NT-proBNP and in restoring LV GLS. At 12 months, the incidence of persisting, abnormal late gadolinium enhancement and increased proportion of extracellular matrix was significantly less in the ARNI group.Conclusion Olmesartan was demonstrated effective in the multi-modality therapy of CHFmrEF and MF in patients with AH and dyslipidemia. ARNI was superior to olmesartan in this regard, but further research of this issue is required.