COVID-19 and the Heart: A Bounty of Questions

In the early months of the pandemic, alarms sounded after doctors noticed that people with heart disease were faring a lot worse than others who had contracted COVID-19. Almost a year later, researchers are still pondering why these patients get sicker and die at higher rates. But they’re now puzzling over an arguably bigger mystery: why some who never even had heart issues – or risk factors for them —are experiencing cardiac problems after getting the disease.  

Compounding that mystery: emerging evidence that healthy people who were infected with SARS-CoV-2, the coronavirus that causes COVID-19, are now having heart problems, too, despite having no symptoms at all. 

Researchers say additional studies must be done to know more, but they concede these are worrisome developments that could portend long-term health issues for millions of people diagnosed with COVID-19.   

“The emerging evidence that even people who were not hospitalized for COVID-19 or had minimal if any symptoms still experience cardiac injury is a serious long-term concern,” said David Goff, M.D., Ph.D., director of the NHLBI’s Division of Cardiovascular Sciences. “And an urgent public health concern.”  

Sorting through the myriad heart-related questions posed by COVID-19 has been daunting from the start and has stumped physicians and researchers alike.  

For example, when doctors first started putting patients on ventilators due to respiratory problems and saw them die of heart failure, they were not unduly alarmed. Viruses frequently trigger heart inflammation, or myocarditis, and outcomes vary, although the condition often resolves on its own. But back then, doctors simply did not know something else more complicated may have been in play.  

“The miscue early in the pandemic was that SARS-CoV-2 was a respiratory virus,” said Eric Topol, M.D., professor of molecular medicine and executive vice president at Scripps Research. Indeed, although the virus spreads through the air and mostly infects lungs and airways, researchers have found that it moves stealthily through the body, wreaking havoc on many organs in its path, including the heart. “In fact,” Topol said, “the heart is a principal target for SARS-CoV-2.” 

The damage to the heart can be both direct and indirect, he explained. When the coronavirus attacks other organs such as the kidneys, lungs, and liver, it stresses the heart by making it work harder. But the virus can directly infect heart muscle cells, weakening them and limiting their ability to beat after just 72 hours. This leads to an array of complications, including myocarditis; arrhythmias (irregular heart rates or rhythms); cardiomyopathy (enlargement of the heart muscle); and heart failure (inability of the heart to pump blood well).  

New studies are also showing how the virus damages blood vessels throughout the body, including those that supply the heart, a problem that might be much more common than myocarditis. 

“This direct damage to the blood vessels can lead to small blood clots and inflammation in the heart, and this process might cause long-term damage, such as fibrosis and heart muscle damage, that increases the risk of heart failure,” Goff said.   

According to recent studies, between 10% and 30% of patients hospitalized with COVID-19 had high levels of troponin, a protein that gets into the blood when there is damage to heart cells. Despite that this damage is usually minimal, compared to in those without cardiac injury, these patients still are more likely to die.   

For some people, however, the only signs of having had the virus are the resulting cardiac problems. Even healthy, young individuals with only mild symptoms, or none at all, have developed myocarditis, heart failure, and arrhythmias, Topol explained. This could be troubling, he added, given that asymptomatic cases of COVID-19 make up at least 30% of all cases.   

The actual number of people who develop cardiac problems after contracting the virus remains unknown, and new research suggest the incidence of myocarditis might be under 1%, less than previously thought.  

Still, Topol said, it only takes doing the math to worry—not just about rising cases of myocarditis, but the range of heart conditions emerging among people who have had COVID-19. “With the number of known cases, plus the asymptomatic ones, even if just 0.5% develop cardiac problems, we will have a huge issue in our hands,” he said.     

In fact, physicians and researchers already are seeing evidence of lingering symptoms and heart abnormalities months after an individual has recovered. “We need more research, but there is a significant risk that if SARS-CoV-2 infects your heart cells, you will become more susceptible to cardiovascular disease,” Goff said. “And this could lead to an increase in heart failure in the future.”  

Taking steps to lower risks  

While researchers dig deeper, Goff said all Americans should ramp up their efforts to minimize any risks for cardiovascular disease, such as high blood pressure and obesity. It matters, he said.  

Research has shown that cardiometabolic syndrome – a condition that includes obesity, diabetes, high cholesterol, and hypertension – is a major risk factor for cardiovascular disease and has emerged as a prominent driver of worse outcomes for patients with COVID-19. The relationship is so strong that researchers suggest coronavirus disease–related cardiometabolic syndrome (CIRCS).   

Having either cardiovascular disease or any of its risk factors at least partly explain the higher rates of mortality and severe illness among younger patients, particularly those in racial and ethnic minority populations, Goff said.  

And research suggests patients of any age who recover from severe COVID-19 still could face a worsening of their cardiovascular health, he added.     

“Following a healthy diet, like the DASH eating plan and staying active are two important ways to maintain your heart health,” Goff said. “It’s about prevention all around. When you go out for a walk, remember to wear a mask and watch your distance, and when you get back home, wash your hands.” 

An unexpected fallout 

If the heart has taken a big hit from COVID-19, new evidence suggests that during the pandemic, the diagnosis, management, and treatment of heart disease has taken one, too.   

Studies have found that the rise in COVID-19 cases has been followed by a decrease in the number of people diagnosed with cardiovascular disease, in part because fewer people are visiting their doctors or going to the hospital when they suspect problems. This has resulted in an increased risk among many for cardiac events like heart attacks and strokes, setting up more people for disability in the future, Goff said. It’s also meant an increase in mortality from heart disease.  

“We are already facing the problem of people who are having a heart attack or a stroke and don’t call an ambulance for fear of getting the virus at a hospital,” Goff said. “So, we have seen a significant increase in cardiovascular deaths that are not directly related to COVID-19.”  

For now, he offered a simple fix: “People with heart conditions should maintain a healthy lifestyle, take their prescribed medications, and keep all their medical appointments during the pandemic,” Goff said. “I can’t stress enough how important that is.”