A 61-year-old man complained to the district doctor about the compression attacks sternum, which occur when walking up to 200 m and disappear if stopped. Considers myself sick for about a year. The boundaries of the heart are normal, the tones are moderately muted, ChCC = Ps = 76 / xv., AT - 130/80 mm Hg. Art. What is the most likely diagnosis in a patient?