A 31-year-old drug-addicted person complains of a cough with bloody expectorations, dyspnea, persistent fever, and leg edemas. The jugular veins are distended. There is a coarse pansystolic murmur detected above the base of the xiphoid process and in the second intercostal space on the left, close to the edge of the sternum. Heart sounds are clear, arrhythmia is detected, heart rate is 128/min., pulse — 82/min., blood pressure is 100/70 mm Hg. What is the most likely diagnosis?