»In which the heart muscle mass continues to grow

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.

The finding upturns what has long been conventional wisdom: that the heart cannot produce new muscle cells and so people die with the same heart they were born with.

About 1 percent of the heart muscle cells are replaced every year at age 25, falling to less than a half of a percent per year at age 75, concludes a team of researchers led by Dr. Jonas Frisen of the Karolinska Institute in Stockholm.