Other viruses are known to infect the heart and spur inflammation. Coxsackieviruses, for example, are a major cause of myocarditis and other heart-muscle defects. When viral pathogens such as these strike, people usually develop chest pains, shortness of breath or some other overt signs of illness. SARS-CoV-2, the virus responsible for COVID-19, is different.
Not only do few people diagnosed with coronavirus-induced myocarditis complain of cardiac issues, but they can also have few or no symptoms of infection whatsoever.
Raul Mitrani is a cardiac electrophysiologist at the University of Miami Miller School of Medicine in Florida. Last year, Mitrani and his colleagues gave a name to the constellation of heart-related problems observed among people recovering from COVID-19: post-COVID-19 cardiac syndrome
1. “There are a lot of unknowns still,” Mitrani says. “But what we’re ultimately worried about is heart decompensation and dangerous arrhythmias.” The former involves a sudden worsening of heart failure; the latter is an uneven heartbeat. Both can trigger sudden cardiac death.
Scientists have begun to study the phenomenon in the lab, exposing heart tissue derived from stem cells to SARS-CoV-2 and chronicling the damage inflicted. And clinicians are continuing to track people who have had COVID-19 to better understand the long-term cardiac risks.
Although it’s too soon to make definitive conclusions, the extent of cardiac injury and inflammation observed using magnetic resonance imaging (MRI)—the most definitive and comprehensive tool for diagnosing myocarditis—has put the field on high alert.
“We need to understand more about what these MRI abnormalities mean,” says Saurabh Rajpal, a cardiologist at the Ohio State University Wexner Medical Center in Columbus.
From the earliest days of the COVID-19 pandemic, it was clear that the coronavirus was wreaking havoc on the heart. Initial reports described people with worryingly high levels of the protein troponin in their blood, an indicator of cardiac injury.
Acute heart failure, arrhythmias and blood clots are all problems for people hospitalized with COVID-19. Autopsies frequently show signs of the virus’s genetic material inside cardiac tissue, a consequence of the fact that the receptor through which SARS-CoV-2 invades lung cells is also found in abundance in heart tissue.
Researchers soon found out that the heart-wrecking effects of COVID-19 are not limited to people with symptoms, or even to people with active infections. Last July, researchers described
2 abnormal imaging findings on heart scans taken from people who had recently had COVID-19, some of whom were asymptomatic. Of the 100 people studied, 78 had some kind of heart irregularity around two months after infection—and 60 showed signs of ongoing myocardial inflammation.
Healthy heart muscle (
left) have long fibres that allow them to contract. The virus SARS-CoV-2 causes these fibres to break apart (
right), which might explain the lasting cardiac effects seen in people who have had COVID-19. Credit: Gladstone Institutes
“That was quite worrisome and created quite a stir,” Mitrani says. In particular, the idea that COVID-19 could stealthily inflict sustained damage on the heart raised alarm bells among the sports-medicine community, given the particularly grave risk that myocarditis poses for athletes. Citing “potential serious cardiac side effects”, last August, several US university leagues temporarily put their seasons on hold.
COVID’s cardiac connection
This is worrying
