New research led by Australia's University of Queensland (UQ) has discovered how COVID-19 damages the heart, opening the door to future treatments.

The study, published in Immunology, has found that while both COVID-19 and influenza are severe respiratory viruses, they appeared to affect cardiac tissue very differently.

The research used actual cardiac tissues collected during autopsies from seven COVID-19 patients from Brazil, two people who died from influenza and six control patients.

Initial study found that COVID-19 damaged the DNA in cardiac tissue, which wasn't detected in influenza samples.

"When we looked at the influenza cardiac tissue samples, we identified that it caused excess inflammation," UQ Professor John Fraser said in a statement issued by the university on Friday.

"Whereas we found COVID-19 attacked the heart's DNA, probably directly and not just as a knock-on from inflammation," he said.

"Our study has highlighted that the two viruses appear to affect cardiac tissue very differently, which we want to get a better understand of in larger cohort studies."

UQ Diamantina Institute researcher Arutha Kulasinghe said that during the study the researchers couldn't detect viral particles in the cardiac tissues of COVID-19 patients, but they found tissue changes associated with DNA damage and repair.

"DNA damage and repair mechanisms foster genomic instability and are related to chronic diseases such as diabetes, cancer, atherosclerosis and neurodegenerative disorders, so understanding why this is happening in COVID-19 patients is important," Kulasinghe said.

He said that in comparison to the 2009 flu pandemic, COVID-19 has led to more severe and long-term cardiovascular disease but what was causing that at a molecular level wasn't known.

"What we have categorically shown is that COVID is not 'just like the flu'," said Fraser.

"This study helps us understand how COVID-19 affects that heart, and that is the first step in working out what treatments might be best to repair that heart."