Mild COVID-19 infection is very unlikely to cause lasting damage to the structure or function of the heart, according to new research supported by staff at the Royal Free Hospital.

Healthcare workers recruited at the Royal Free Hospital, including a number of its staff, were among those to participate in the study. The findings are hoped to provide reassurance for the public about the long-term impact of mild COVID-19 infections.

Professor Marianna Fontana (pictured), director of the UCL cardiac magnetic resonance unit and principal investigator at the Royal Free Hospital, explained: 

“This is very important research, as it will reassure patients that a mild COVID-19 infection is unlikely to cause long-term problems. That’s really important, because we know that the majority of those who experience COVID-19 only have mild symptoms – so it will come as good news to a lot of people to hear that mild infection has not been linked with longer term heart damage.

“This has been the largest study looking at mild COVID-19 infection to date, with 149 participants recruited across the Royal Free Hospital and Barts Hospital. Now researchers will be able to turn their attention to the impact of more severe COVID-19 infection.”

The findings follow concerns that the complications associated with severe COVID-19 infections – such as blood clots, inflammation of the heart and heart damage – may also affect those with mild cases. Fortunately, this appears not to be the case.

Researchers identified participants from the COVIDsortium, a study which took place at the Royal Free Hospital and two other London hospitals, which involved taking weekly samples of blood, saliva and nasal swabs from healthcare workers. Six months after mild infection, they looked at the heart structure and function by analysing heart MRI scans of 74 healthcare workers with prior mild COVID-19 and compared them to the scans of 75 healthy age, sex and ethnicity matched controls who had not previously been infected.

The findings showed that there was no difference in the size or amount of muscle of the left ventricle – the main chamber of the heart responsible for pumping blood around the body – or its ability to pump blood out of the heart. The amount of inflammation and scarring in the heart, and the elasticity of the aorta remained the same between both groups. They also found that there were no differences in the markers of heart muscle damage between the control group and those who had mild COVID-19 infection.

This research has been funded by the British Heart Foundation and Barts Charity.