Heart muscle cells (cardiomyocytes) do not regenerate during adult life. When heart muscle is damaged by injury or decreased blood flow, functional contracting heart muscle is replaced with nonfunctional scar tissue. Congestive heart failure, a common consequence of heart muscle or valve damage, affects approximately 5.8 million people in the United States according to the American Heart Association and this year, it is estimated that about 1.3 million people will have a heart attack, which is the primary cause of heart muscle damage.
