ST LOUIS (BLOOMBERG) - Heart damage from Covid-19 extends well beyond the disease's initial stages, according to a study which found that even people who were never sick enough to require hospitalisation are in danger of developing heart failure and deadly blood clots a year later.
Heart disease and stroke are already the leading causes of death worldwide. The increased likelihood of lethal heart complications in Covid-19 survivors - who number in the hundreds of millions globally - will add to its devastation, according to the study, which is under consideration for publication by a Nature journal.
"The after-effects of Covid-19 are substantial," said Dr Ziyad Al-Aly, director of the clinical epidemiology centre at the Veterans Affairs St Louis Health Care System in Missouri, who led the research.
"Governments and health systems must wake up to the reality that Covid-19 will cast a tall shadow in the form of long Covid, and has devastating consequences. I am concerned that we are not taking this seriously enough."
The chances of a heart attack, stroke, or other major cardiovascular events in the first 12 months of Covid-19 recovery increase with the severity of the initial illness, the researchers found.
They compared the risks of heart complications in 151,195 veterans who survived Covid-19 with the risk in more than 3.6 million of their peers who did not contract the pandemic disease.
The data was collected from the largest integrated healthcare system in the US. Most of its users are white and male, which may limit how generalisable the study's findings are to other groups, the authors said.
They found non-hospitalised Covid-19 patients had a 39 per cent increased risk of developing heart failure and a 2.2-fold increased risk of a potentially deadly blood clot, known as a pulmonary embolism, in the following year, compared with someone who did not develop the disease.
That works out to an extra 5.8 cases of heart failure and 2.8 cases of pulmonary embolism for every 1,000 Covid-19 patients who were never hospitalised.
Being hospitalised for Covid-19 is associated with a 5.8-fold increased risk of cardiac arrest and almost a fourteenfold greater chance of myocarditis, or inflammation of the heart muscle, the study found.
Covid-19 patients who needed intensive care are at significantly greater risk, with almost one in seven suffering a major adverse cardiac event that they would not have otherwise had within a year.
Researchers are still trying to unravel the causes of heart damage in Covid-19 patients.
Possible mechanisms include lingering damage from direct viral invasion of heart muscle cells and the cells that line blood vessels, blood clots and aberrant and persistent inflammation, the authors said.
The findings from natural disasters and previous pandemics suggest indirect effects of Covid-19, including social isolation, financial distress, changes in dietary habits and physical activity, as well as trauma and grief, may also influence the risks for cardiovascular disease, they said.