Myocarditis, COVID-19 and Heart Failure: Clearing Up the Confusing Data 

Before the COVID-19 pandemic, the term myocarditis — referring to inflammation of the heart muscle — was not exactly well known outside of the medical field. But over the nearly two years of the pandemic, studies have linked COVID-19 to a greater risk of mostly mild myocarditis without further implications.

What isn’t widely known even now is that any viral infection, not just COVID-19, can cause myocarditis. Most cases resolve on their own, explains Sandra Chaparro, M.D., cardiologist and director of the Advanced Heart Failure Program at Miami Cardiac & Vascular Institute. But it depends on the individual’s overall situation. 

Sandra Chaparro, M.D., cardiologist and director of the Advanced Heart Failure Program at Miami Cardiac & Vascular Institute. 

If there are other underlying health issues that can affect cardiovascular function, myocarditis — whatever the cause — can result in hospitalization, heart failure, and even death. This is true especially with the development of cardiomyopathy, a disease of the heart muscle that can lead to heart failure – when the heart is too weak to pump blood throughout the body.

“In general, there are different ways you can develop myocarditis,” explains Dr. Chaparro. “You can develop myocarditis by direct injury of the heart or indirect, for example, when you have a multisystem inflammatory syndrome, the heart gets affected, and also you have different organs failing.   Obviously, that prognosis is worse. But, in general, myocarditis is a temporary inflammation of the heart that usually resolves without treatment.”

A recent study by the U.S. Centers for Disease Control and Prevention (CDC) again raised concerns about myocarditis and COVID-19. During March 2020 through January 2021 period, patients with COVID-19 had nearly 16 times the risk for myocarditis, compared with patients who did not have COVID-19, the CDC said. Researchers reached this conclusion after reviewing a large, U.S. hospital-based administrative database from more than 900 hospitals.

But the study, Dr. Chaparro points out, was observational and did not delve into medical histories.

“So, they were not digging into the details of every single patient,” said Dr. Chaparro. “But because it’s data from 900 hospitals, it would give us a big idea of where we are in terms of COVID and myocarditis. Yes, it’s 16 times higher risk in the patients who had COVID compared to those that did not.”

Dr. Chaparro adds that with COVID-19 we see an increase in cases of myocarditis. “That’s really important. If you consider the overall pandemic, myocarditis is still diagnosed in a relatively small number of patients with COVID.”

Heart Issues ‘Not at the Top of COVID Presentations’

Because the majority of the patients that develop COVID-19 infection will not end up in the hospital, there are many questions as to any impact on the cardiovascular system. And most patients who are hospitalized, present with primarily respiratory symptoms, not necessarily related to the cardiovascular system.

“Along the spectrum of conditions, cardiac disease is not at the top for COVID presentations,” said Dr. Chaparro. “Yes, you can have some episodes of occasional palpitations or shortness of breath that can be confused with other symptoms, but it’s really infrequent to see cardiac presentations.”

For example, patients who develop heart failure related to COVID are ” rare and that’s usually related to direct injury of the virus to the heart, and it’s usually through the pathway of myocarditis.” Moreover, if there are co-existing conditions or comorbidities, then those patients are at a higher risk of complications, she said.

The New Reality: Risks from ‘Long COVID’

Much is still unknown regarding the impact of lingering COVID symptoms, or “long COVID,” on the cardiovascular health of those previously infected. Depending on symptoms, those patients may need to go through several cardiac screenings. Common long COVID symptoms include fatigue, shortness of breath, chest pain or fast or pounding heartbeat.

“That’s the new reality,” said Dr. Chaparro. “We see patients with long COVID. We review their history, how severe was the initial infection and whether they have been vaccinated. All those things are important information to make their diagnosis and produce a plan. We have seen a few patients with long COVID.”

Some long COVID patients, she adds, will go through a battery of tests that may include electrocardiograms, echocardiograms, cardiac MRI, cardiac catheterizations, cardiac-pulmonary stress tests. A multidisciplinary team will then help pinpoint any possible cause of symptoms.

“It’s sometimes really, really hard to determine a cause but we’re doing a lot of studies and follow-ups with these patients,” said Dr. Chaparro. “The situations can be complex because we’re still learning how to diagnose long COVID and what to do with the information to help patients.”