On the 3rd day after the acute anterior myocardial infarction a 55 y.o. patient complains of dull ache behind his breast bone, that can be reduced by bendi- ng forward, and of dyspnea. Objectively: AP- 140/180 mm Hg, heart sounds are dull. ECG results: atrial fibrillation wi- th frequence of ventricular contractions at the rate of 110/min, pathological Q wave and S-T segment raising in the ri- ght chest leads. The patient refused from thrombolisis. What is the most probable diagnosis?