Although most people survive a heart attackTrusted Source initially, the risk of death significantly increases over the following years.

In fact, 65% of peopleTrusted Source who have a heart attack over the age of 65 die within eight years of the initial incident. This is at least partly because while a person may survive an initial heart attack, the heart attack itself, which leads to the heart tissue being deprived of oxygen and then dying, does not regenerate in adult humans.

In a recent animal study, researchers identified a mechanism that allowed them to treat heart tissue and make healthy mice’s hearts more resilient before a heart attack.

The study’s results appear in Nature Cardiovascular Research.

Prof. James Leiper, Ph.D., Associate Medical Director at the British Heart Foundation and Professor of Molecular Medicine in the School of Cardiovascular and Metabolic Health at the University of Glasgow, U.K. told Medical News Today in an email:

“Most heart attacks are caused by coronary artery disease which can cause your coronary arteries to become narrowed. The narrowing is due to a gradual buildup of fatty deposits called atheroma. If a piece of atheroma breaks off, a blood clot forms around this to try and repair the damage to the artery wall. This clot can then block your coronary arteries causing the heart muscle to be starved of blood, oxygen, and vital nutrients, leading to heart muscle death.

The amount of damage to the heart muscle depends on the size of the area supplied by the blocked artery. As heart muscle is unable to regenerate it never fully repairs. Instead, scar tissue forms in place of healthy cardiac muscle.”

Cardiomyocytes are a type of cell in the heart that is responsible for the contraction of the muscle. This contraction of the muscle is essential for the heart to be able to squeeze blood around the body, in response to electrical signaling that maintains the heartbeat. When these cells are damaged in a heart attack, the heart loses some of its ability to squeeze blood around the body as effectively.

While cardiomyocytes are able to proliferate in human fetuses, this ability is lost in mature adult humans. It is believed this is partly due to an evolutionary trade-off that sees the ability of mature cardiomyocytes to proliferate decline with contractile strength. This means damage caused by events such as heart attacks can not be corrected.