Human heart capable of making muscle cells
In a finding that may open new approaches to treating heart disease, Swedish scientists have succeeded in measuring a highly controversial property of the human heart: the rate at which its muscle cells are renewed during a person's lifetime. Ref. Source 9
With the body renewing itself over a seven year period I do not know why it has taken a scientist this long to map it out. This is why every seven years you can have a change of allergies or change of appetite. Humans have a whole new body and that includes the heart. Our body is always replacing cells.