A 56-year-old patient complains of unbearable pain behind her sternum that does not stop even after taking three tablets of nitroglycerin. She has history of essential hypertension since the age of 45, ischemic heart disease, and frequent stresses at work. Objectively, the following is observed: noti-coable skin pallor, acrocyanosis, cold sticky sweat, respiratory rate 24/min, inspiratory dyspnea, heart rate - 118/min, the pulse is rapid, of poor volume, blood pressure - 90/50 mm Hg. The left border of the relative cardiac dullness is shifted outwards. Auscultation detects weakened heart sounds at the apex, tachycardia, and gallop rhythm, ECG registers OS waves in leads I, a VL, V4-V6. What is the most likely diagnosis in this case?