The aim – to develop a diagnostic system that takes into account the peculiarities of clinical, instrumental and laboratory indicators in patients with STEMI against the background of wartime and will allow to objectify a tendency to a more difficult hospital course of ACS.Materials and methods. We studied a cohort of patients (n=133 individuals, 77.4 % men, average age 61.8±0.9 years) with STEMI, part of which (group 1) was hospitalized from February to May 2019 (n=87), while another part of which (group 2) was hospitalized in the period from February 24, 2022 to March 2023 (n=46) within the first 24 hours from the development of symptoms of the disease (average time of admission 5.2±0.4 hours). The groups were compared according to the clinical and anamnestic and laboratory parameters of the first day.Results and discussion. It was found that in the Ukrainian population during wartime, patients with STEMI are admitted to the hospital later, have a more burdensome history of cerebrovascular diseases, a greater number of significant coronary stenoses, a higher percentage of smokers, and also have higher heart rate levels upon admission, ESR, triglycerides, leukocytes (at the expense of lymphocytes and monocytes), as well as platelets (with lower indicators of their size inhomogeneity). Also, invasive treatment of these lesions leads to slightly worse results on the TIMI and MBG scales. Informativeness of hematology analysis indicators and other markers of inflammation/stress on the first day of STEMI in wartime was evaluated for predicting the risk of an complicated course of the hospital period (development of cardiac death, signs of LVEF, ventricular tachyarrhythmias, stent thrombosis, acute renal dysfunction, recurrence of ACS/angina). It was found that predictors of the undesirable course of STEMI during wartime are: heart rate > 70/min, ESR > 10 mm/h, glucose level > 8.5 mmol/l, leukocytes > 13 · 109/l, lymphocytes > 2 · 109/l, platelets > 270 · 109/l, large (>12 fl) platelets < 27 %, triglycerides > 1.3 mmol/l, as well as combined criteria made up of these indicators. Thus, the 6-component score (heart rate, ESR, glucose, levels of leukocytes, lymphocytes, and platelets) had an area under the ROC curve of 0.87 (for values > 30 units – BP 6.39 (2.16–18.9), p<0.0001) when determining the risk of an undesirable course of ACS in patients during wartime. These predictors are specific to the stress-induced effects of war and are not informative in peacetime STEMI patients.Conclusions. The coexistence of acute stress caused by STEMI with chronic exposure to stress-associated wartime factors can worsen the course of the hospital period of STEMI, which is associated with an increase in heart rate, ESR, glucose level, leukocytes, lymphocytes, triglycerides, platelets with a decrease in their inhomogeneity in size. Taking into account these features allows predicting the risk of a complicated course of the hospital period of the STEMI in wartime.