After a long periode of subfebrility a patient registered increase of dyspnea, pain in the right hypochondrium, leg edemata. Objectively: neck veins are edematic. Ps is 120 bpm, sometimes it disappears during inspiration. Heart sounds are very weakened. ECG showed low-voltage waves of ventricular complex. A month ago there was raise of ST V1 — V4 segment. Cardiac silhouette is enlarged, roundish. What is the most probable diagnosis?