Background. The use of b- blockers in acute coronary syndrome (ACS) is recommended for all patients, who has not contraindications. The study of the effects of esmolol during percutaneous coronary intervention (PCI) remains relevant. Objective. To evaluate the features of the effect of esmolol (Biblock, “YURiA-PHARM”) on heart rate and blood pressure in patients with ACS during PCI.Materials and methods. The study included 30 patients, 15 men and 15 women, who were hospitalized in a specialized cardiology department with ACS with elevation of the ST segment. All patients underwent a general clinical examination, ECG recording in 12 leads, PCI according to the standard protocol with ECG and blood pressure monitoring. All patients were given infusion of esmolol before the standard therapy. The level of heart rate reduction, systolic blood pressure (SBP), diastolic blood pressure (DBP), the correlation of heart rate reduction during esmolol infusion with the clinical and functional parameters of patients and the degree of coronary artery (CA) damage were analyzed.Results. Decreased heart rate and blood pressure during infusion of esmolol in all patients. Before the infusion, the heart rate av-eraged (109.8 ± 4.0) beats per minute. After the infusion – (92.8 ± 3.2) beats per minute, (p < 0.001) with an average duration of infusion (18.2 ± 2.3) minutes. The decrease in SBP levels during infusion occurred on average by (22.8 ± 2.5) mm Hg, DBP – by (16.0 ± 2.1) mm Hg, no patient had hypotension. According to the results of correlation analysis, it was found that the decrease in heart rate with the use of esmolol has a correlation with the average age of patients (r = -0.47, p = 0.0012), with the presence of multivascular coronary artery disease (r = -0.38, p = 0.002). Weaker negative correlation was found with the initial level of SBP (r = -0.28, p = 0.015), the presence of a history of myocardial infarction (r = -0.27, p = 0.005), the presence of signs of left ventricular hypertrophy (LVH) on the ECG (r = -0.22, p = 0.008), and a history of arterial hypertension that was not treated according to current recommendations (r = -0.21, p = 0.032).Conclusions. The use of esmolol solution in patients with ACS who have supraventricular tachycardia and elevated blood pressure during PCI can improve control of heart rate, SBP and DBP, a significant decrease is observed after 10 minutes of dose titration. Careful titration of esmolol solution and monitoring of ECG and blood pressure revealed no side effects, including bradycardia and hypotension, which indicates a high safety profile of the drug.