Science Needs More Time to Understand Myocarditis and COVID-19

At least once every year, myocarditis occurs as a headline tragedy in the US.

The rare heart inflammation condition can end in sudden and initially inexplicable dread, often cutting down a seemingly healthy young athlete at some level of competition.

Only 1 out of every 500,000 cases of the disease results in sudden cardiac arrest, but the anecdote of just 1 high school basketball player collapsing and dying on the court is enough to stick with a person.

One of the leading causes of myocarditis is a viral infection, like influenza. When the COVID-19 pandemic hit, fear grew as investigators sought to learn how the virus might impact myocarditis rates. Even though young athletes might be at lesser risk of COVID-19 outcomes, could this silent killer raise in prevalence?

The worry and early research into the myocarditis and COVID-19 link fueled debates over the resumption of NCAA athletics seasons. Smaller samplings in August and September showed astonishingly high rates of the potentially deadly disorder that led to athletic departments across the country to either opt out of sports, or reconsider plans to play.

But as more and more data became available, both through surveys and antidotal evidence, theories change to believe myocarditis may not actually be a huge byproduct of the virus.

Leslie Cooper, MD, chair of the Mayo Clinic Department of Cardiovascular Medicine and founder of the Myocarditis Foundation, explained how as time went on the risk of the disease seemed to decrease.

“The arc of the story from a cardiac standpoint is the first reports in March and April out of Wuhan, China of hospitalized older patients were that you 30-40% rate of heart damage,” Cooper said. “As the summer went on, it became clear from the first MRI findings, that there was heart muscle damage that was longer lasting after people got out of the hospital, say 2 months.”

The Need for Long-Term Data

In a sense, the data regarding this connection has been all over the place, but as time has passed more and more studies have shown only minor links between myocarditis and COVID-19.

In a published study released in September, researchers found up to 15% of COVID-19 patients suffered from myocarditis, using a sample of non-hospitalized patients.

However, in a recent study in which Jonathan Kim, MD, chief of Sports Cardiology at Emory University School of Medicine, was a co-author, researchers found few cases of inflammatory heart disease detected in a study of 789 professional athletes.

In the study, published in JAMA Cardiology, the researchers found abnormal cardiac screenings in 30 athletes and just 3 instances of myocarditis.

But hasn’t been all good news.

While it was likely not myocarditis, something abnormal kept showing up on cardiac imaging, even for patients with mild or moderate COVID-19 cases.

“In all these imaging findings and MRI’s, we're seeing something else,” Cooper said. “Now, we do not know what the something is, it could be an edema, extra fluid from leaky blood vessels. We also don’t know the clinical impact. Do you get a higher risk of death, or a higher risk of heart failure if you exercise following COVID-19.”

There are currently at least 10 MRI registry studies in the US looking at pinpointing the long-term damage from a cardiology standpoint from COVID-19.

Kim, who also serves as team cardiologists for several college athletic departments and professional franchises including the Atlanta Hawks and Atlanta Falcons, said he expects to have a better understanding on the rates of inflamed heart muscles and other cardiac injuries among college and professional athletes in the coming months from registry data.

“Certainly, with the rigorous screening recommendations that are out there, we will be able to benefit from data,” Kim said. “I think the data or really be able to answer that, and those data should be coming out shortly.”

More Screenings

Even if the current belief is that rates will not skyrocket due to COVID-19, Kim said the recommendations will be conversative until more conclusive data is found.

“We were doing very conservative screening on basically anybody who had COVID, that was an athlete who had any symptom, I mean, even if it was just a minor cough for a day, we were screening,” he said. “We weren't seeing really much cardiac pathology at all. And so, because of that, we actually updated our consensus recommendations and felt that those who are asymptomatic and with mild symptoms, do not need screening because we weren't observing a lot.”

“There’s no other viral infection in the world where we recommend screening,” Kim added. “You can have the worst flu in the world and when you’re better if you’re an athlete you can get back to train. Obviously there’s a gradual escalation because you’ve been sick, but nobody’s doing echo's and EKG’s and troponin testing even after a bad case of the flu for an athlete that’s recovered and feeling better.”

Kim said the 3-6 month recommendation for athletes is not necessarily based on rigorous evidence, but there is clear time that will allow the inflammation to resolve itself.

Intense physical activity following a myocarditis diagnosis could make the inflammation worse, increasing the risk substantially of dangerous heart rhythms and sudden cardiac arrest.

“So, you put all that together, there's a little bit of a conservative timeframe about no exercise, physical activity,” Kim said. “In terms of why some people can be 3 versus other 6 may just be dependent on how significant of a clinical myocarditis course that that individual athlete had.”

In that time period, the athlete then must undergo blood and imaging testing before they are able to go back into play.

“We were doing very conservative screening on basically anybody who had COVID, that was an athlete who had any symptom, I mean, even if it was just a minor cough for a day, we were screening,” Kim said. “We weren't seeing really much cardiac pathology at all. And so, because of that, we actually updated our consensus recommendations and felt that those who are asymptomatic and with mild symptoms, do not need screening because we weren't observing a lot.”

The recommendations did call for more conservative screenings for patients with more severe symptoms, particularly for things like shortness of breath or chest pains.

However, in absence of data, personal experiences has shaped Kim’s view on the issue and after doing countless screenings of young athletes in the greater Atlanta area he does not believe COVID-19 will ultimately be proven to produce large numbers of myocarditis cases.

But until proven, he expects the sports cardiology world to remain cautious on this link.

“Nobody is not respecting the virus and the potential in that association between potential cardiac injury,” Kim said. “If you look at hospitalized patients with COVID, there's a lot of cardiac injury. So, we respect the virus tremendously.”

The Danger of Myocarditis

“It’s hard to screen for something that’s very rare,” Cooper said. “So, what we say at the Myocarditis Foundation is if you develop a viral illness or a flu, could you stay away from sports for several days until you feel better? You can gradually return to sport, that will cover most people.”

For those who return but still feel some symptoms, such as persistent shortness of breath, the guidelines recommend additional cardiac monitoring. These guidelines basically insure that the vast majority of people will not have additional cardiac injuries.

In many ways, the year of the pandemic might shape the next decade of the collective cardiac health of the world. Many people adopted more of a sedimentary lifestyle since work began to take place at home and the gym was replaced with home exercise programs. Many people have also changed to unhealthier diets and have increased the use of drugs, tobacco, and alcohol to cope with the stress of the pandemic.

Add that to the individuals who actually contract the virus and are still feeling some of the impact of COVID-19. Cooper said current reports say 40-50% of COVID-19 hospitalized patients still feel shortness of breath 2 months after discharge.

Treatment for myocarditis, which is one of the leading causes of sudden cardiac death, is mainly supportive care. For some patients who suffer from the disease, they will go into fulminant myocarditis, where they can go into cardiogenic shock, where there’s decompensated congestive heart failure with substantially decreased heart function and sometimes death.

And one of the challenges in myocarditis is that the prevalence, even before the COVID-19 pandemic, is not truly known because the majority of cases go undetected because the patients do not even know themselves.

Best Advice for Avoiding Issues

Cooper’s advice remains even if the odds are low, pay attention to your stamina and condition and always consider what could be happening.

“For young athletes who have had a COVID infection, regardless of symptoms, be mindful in the weeks following the infection for shortness of breath from activity, or chest pain and if you develop one of those symptoms you should seek medical evaluations for cardiac or pulmonary reasons.”

While there is still some unknowns regarding how much COVID-19 can directly lead to myocarditis, the easiest way to handle the issue is to mitigate the spread of the virus.

“I think this goes back to something we’ve talked about since day 1 when we were just learning about sequelae from COVID-19 infection, which is just prevention of spread,” Kim said. “This has always been in our radar, this is it's just a novel virus. But as it relates to decreasing the number of cases where there is pathologic cardiac sequalae after a COVID-19 infection, it really goes back again to prevention of spread and listening to all of our public health experts.”