Viral reservoirs
Macrophages residing in vascular tissue can undergo self-renewal and can remain in the tissue for many years, the investigators point out. They suggest that these macrophages may act as viral reservoirs of SARS-CoV-2 RNA in atherosclerotic plaques.
Using an ex vivo model, the researchers also found that atherosclerotic tissue could be directly infected by the virus. And just as was seen in cultured macrophages and foam cells, infection of vascular tissue triggered an inflammatory response. That response induced the secretion of key proatherogenic cytokines, such as interleukin-6 and interleukin-1 beta, which have been implicated in the pathogenesis of atherosclerosis and in an increased risk of cardiovascular events.
“Considering that plaque inflammation promotes disease progression and contributes to plaque rupture, our results provide a molecular basis for how infection of coronary lesions can contribute to the acute cardiovascular manifestations of COVID-19, such as myocardial infarction,” the researchers report.
Another interesting finding was a higher accumulation of viral RNA in the coronary vasculature of the three patients with acute ischemic cardiovascular manifestations, which they say adds to evidence that infection may increase cardiovascular risk.
Dr. Giannarelli points out that the patients in their study died in New York early in the pandemic, before vaccines were available. “They were unvaccinated and likely had little immunity against initial viral strains.”
Dr. Hotez says that when COVID-19 first emerged, many in the medical and scientific communities thought it would closely resemble the original SARS viral infection, which was primarily a respiratory pathogen.
“But it became pretty clear early on this virus was causing a lot of cardiovascular and thromboembolic disease,” he says. “This study provides an insight into the mechanisms involved here.”
Affecting more than lungs
Dr. Hotez pointed out that a recent study reported a 5% increase in cardiovascular deaths during the years 2020-2022, compared with before the pandemic.
“Those peaks of cardiovascular deaths corresponded with specific waves of COVID – the first happening at the time of the initial wave with the original virus and second during the Delta wave. So, there’s no question that this virus is contributing to excess cardiovascular mortality, and this paper appears to explain the mechanism.”
Dr. Hotez pointed out that the new findings suggest the cardiovascular risk may be prolonged well after the acute infection resolves.
“In long COVID, a lot of people focus on the neurological effects – brain fog and depression. But cardiac insufficiency and other cardiovascular events can also be considered another element of long COVID,” he said.
Dr. Giannarelli says her group is now studying whether patients with long COVID have virus in their coronary arteries. She points out that the current studies were a result of a team effort between experts in cardiovascular disease and virology and infectious disease. “We need to collaborate more like this to understand better the impact of viral infection in patients and the clinical manifestations,” she said.
Dr. Hotez says he believes these new findings will have implications for the future.
“COVID hasn’t gone away. The numbers have been going up again steadily in the U.S. in the last few months. There are still a significant number of hospitalizations,” he said.
While it would be unwieldy to ask for a cardiology consult for every COVID patient, he acknowledged, “there is probably a subset of people – possibly those of older age and who have had a severe case of COVID – who we suspect are now going to be more prone to cardiovascular disease because of having COVID.
“We should be vigilant in looking for cardiovascular disease in these patients,” Dr. Hotez said, “and perhaps be a bit more aggressive about controlling their cardiovascular risk factors.”
The study was funded by the U.S. National Institutes of Health, the American Heart Association, and the Chan Zuckerberg Initiative.
A version of this article first appeared on Medscape.com .