The study, published in Circulation Research and announced in a statement from the University of Sydney on TUesday, revealed that while heart attacks do leave scar tissue, new muscle cells are also generated in the injured heart.

This regenerative ability had previously only been observed in animals such as mice, making this the first time it has been clearly demonstrated in humans.

“Until now, we’ve thought that, because heart cells die after a heart attack, those areas of the heart were irreparably damaged,” said Robert Hume, research fellow at the University of Sydney and the study’s first author.

“This discovery shows the heart has a previously unrecognised capacity for self-repair.”

The breakthrough was made using living heart-tissue samples collected from patients undergoing bypass surgery at Sydney’s Royal Prince Alfred Hospital. Researchers were able to identify newly formed muscle cells in areas once believed to be permanently scarred.

Heart attacks can destroy up to a third of the heart’s muscle cells, often leading to heart failure – a chronic condition in which the heart struggles to pump blood efficiently. Cardiovascular disease remains the world’s leading cause of death, making the discovery particularly significant.

“In time, we hope to develop therapies that can amplify the heart’s natural ability to produce new cells,” said Hume, who also leads translational research at Australia’s Baird Institute for Applied Heart and Lung Research.

Professor Sean Lal, the study’s senior author and a cardiologist, said the ultimate aim is to turn this insight into treatments that can actively repair damaged hearts rather than simply manage symptoms, by making new heart cells that can reverse heart failure.

Experts say this breakthrough could form the foundation for future regenerative medicines. This might include therapies that boost the heart’s natural ability to produce new cells, or use gene- or stem-cell-based techniques to encourage regeneration.