Scientists have noticed that the coronavirus Covid-19 increases the chance of a heart attack or stroke for up to a year after infection, especially for those who already have underlying heart conditions. New research, published online in the journal Nature Cardiovascular Research, has identified the mechanisms responsible for these risks.

The research team, led by researchers at New York University’s Grossman School of Medicine, detected this virus in the arteries of eight men and women with a history of atherosclerosis who had died of Covid-19. Also, the coronavirus was found inside local immune cells called macrophages that normally protect the heart by rejecting unnecessary fat molecules in the arteries. Further experiments showed that in response to the infection, the macrophages released inflammatory proteins, called cytokines, two of which have been linked to heart attacks.

“The virus creates a highly inflammatory environment that could facilitate plaque growth, rupture and obstruction of blood flow to the heart, brain and other key organs,” explains the study’s lead author and a postdoctoral fellow in the Department New York University Langone Health Medical Center MD, Natalia Eberhardt.

In addition, research has revealed that the coronavirus affects more people who already have large amounts of atherosclerotic plaque in their arteries, and this partly explains why people with atherosclerosis are more vulnerable to Covid-19.

The researchers say they analyzed tissues infected with strains of the virus early in the pandemic and plan to repeat the study in people exposed to newer variants.