What to Know About Myocarditis

Scientists have learned so much about the novel coronavirus that causes COVID-19 over the past 18 months. But there are still many open questions regarding the long-term effects of COVID-19. However, heart disease does seem to be connected to COVID-19.

In particular, patients infected with the coronavirus often develop a worrisome inflammation of the heart muscle called myocarditis. This inflammation potentially can lead to serious heart disease, and it seems risk of developing it increases after COVID-19 infection.

In a July 2020 study published in JAMA Cardiology, researchers discovered that 78 out of 100 patients recovering from COVID-19 had some kind of cardiac impairment, and 60 of those had myocarditis after recovering, independent of whether or not they had preexisting conditions or how severe their COVID-19 symptoms were.

“We were not expecting that,” says Dr. Sandra Chaparro, a cardiologist at the Miami Cardiac and Vascular Institute who specializes in heart failure and transplantation cardiology and serves as the director of advanced heart failure. That study’s small sample size makes it hard to know just how widespread the incidence of myocarditis really is, she says. But anecdotal evidence from around the world — including at her institute, which has treated several patients with the condition — suggests it’s worth monitoring.

“We’ve seen it in young and old patients,” Chaparro says. One patient in his 40s recovered from COVID-19 but had signs of heart damage after. However, the connection is still not entirely clear. “Sometimes it’s hard to figure out if it was caused by something else or a preexisting condition. And we don’t know what the rate (of myocarditis) is of asymptomatic patients,” she adds.

But the accumulating data and case studies are raising alarms.

[READ: How COVID-19 Affects the Heart in Long Haulers.]

What Is Myocarditis?

Myocarditis is any inflammation of the heart muscle, says Dr. Karol Watson, a cardiologist and a professor of medicine/cardiology at the David Geffen School of Medicine at UCLA. This inflammation can have many causes. A virus like the coronavirus is one of the most common causes, but bacterial infections, chemotherapy drugs or a dysfunctional immune system may also be behind it.

Myocarditis can disrupt the heart’s ability to pump blood and impair the electrical signaling that keeps it beating regularly. It can be mild, and most people don’t have a lot of symptoms, if any, Chaparro says.

In severe cases, myocarditis can cause abnormal heart rhythms, heart muscle disease and heart failure. These patients may need medication and/or mechanical support, like heart pumps, and a small number of patients require a heart transplant, she says.

How Does COVID-19 Affect the Heart?

The coronavirus may cause inflammation in up to three ways. “Like any virus, it can directly attack the heart muscle, causing inflammation and myocarditis,” says Watson, who is also director of the UCLA Women’s Cardiovascular Health Center and the UCLA-Barbra Streisand Women’s Heart Health Program. Heart cells have receptors to which the virus can attach and cause direct myocardial injury, Chaparro concurs.

Second, the virus can also infect the lungs, which become impaired and fail to deliver the amount of oxygen needed to feed the heart. When respiration fails and oxygen levels are too low — called hypoxemia — the overworked and underfed heart may become inflamed.

Third, the coronavirus can, in severe cases, cause what’s known as a cytokine storm, an overreactive immune system response that causes inflammation throughout the body, including the heart. “It is the extreme manifestation of inflammation,” Watson says.

[READ: Heart Disease Prevention: How Much Does Oral Health Matter?]

Role of Preexisting Conditions

Watson says that many cardiac conditions follow a “two-hit” hypothesis. “They may have one hit, which is hypertension or obesity or something else. Then when a second hit comes along, such as COVID, the severe manifestations are expressed,” she says.

This is why those with preexisting conditions that affect the heart, such as diabetes, obesity, high blood pressure and advanced age, are at such higher risk of death than those without such conditions. However, even those with no preexisting conditions can develop myocarditis, as found in the JAMA Cardiology study.

Myocarditis, Pericarditis and COVID-19 Vaccines

Three COVID-19 vaccines are now authorized for emergency use in the U.S., helping to significantly improve the course of the pandemic. However, as with any medical intervention there can be side effects associated with these life-saving vaccines. Myocarditis and a similar condition called pericarditis — inflammation of the pericardium, a thin, saclike membrane around the heart — have been observed in some people who’ve received the vaccine.

Most of these cases have been observed in male adolescents and young adults aged 16 or older. Incidents of heart inflammation were more common after the second dose of the mRNA vaccine. Confirmed cases have typically developed several days after vaccination, the Centers for Disease Control and Prevention reports.

So how big a concern should this potential complication of vaccination be? According to the CDC, as of June 23, 2021, more than 177 million people have received at least one dose of a COVID-19 vaccine in the U.S. Since April, more than 1,000 cases of inflammation of the heart have been reported to the CDC’s Vaccine Adverse Event Reporting System.

To break this down further, the CDC reports that for every million doses of the vaccine, there have been:

— 67 cases in boys aged 12 to 17.

— 9 cases in girls aged 12 to 17.

— 56 cases in young men aged 18 to 24.

— 6 cases in young women aged 18 to 24.

— 20 cases in men aged 25 to 29.

— 3 cases in women aged 25 to 29.

As the data prove, these events are very rare and appear to be connected to the Moderna or Pfizer-BioNTech vaccines, both of which use mRNA — a snippet of genetic code from the virus — to stimulate the immune system to develop antibodies against COVID-19.

Despite the potential concern regarding heart inflammation, the CDC and many public health experts recommend the vaccine as the best option to stay safe from COVID. Dr. Lisa Doggett, senior medical director for HGS AxisPoint Health, a care management services company based in Westminster, Colorado, and a newly appointed fellow with American Academy of Family Physicians’ Vaccine Science Fellowship, notes that the CDC is investigating these “very rare reports of possible complications, but the risk of getting infected with COVID-19 is far more than any potential risk from the vaccine.”

The CDC also notes that most cases of heart inflammation associated with the vaccine were mild and 79% of people who experienced post-vaccination myocarditis or pericarditis had recovered fully. According to one study of 23 men who developed myocarditis, after one week, 16 had recovered while the remaining seven still had some chest discomfort.

[Read: The Best Diets for Your Heart]

Signs of Myocarditis

Many cases of myocarditis are asymptomatic, Watson says. Some signs or symptoms of myocarditis can include:

— Chest pain.

— Rapid or abnormal heart rhythms, or arrhythmias.

— Shortness of breath, at rest or during physical activity.

— Fluid retention with swelling of your legs, ankles and feet.

— Fatigue.

— Other signs and symptoms of a viral infection, such as a headache, body aches, joint pain, fever, a sore throat or diarrhea.

Physicians test for myocarditis with imaging studies such as electrocardiograms and echocardiograms. Blood tests also may reveal biomarkers, chemicals that reveal heart muscle damage or heart failure, Chaparro says.


Treatment depends on the symptoms. “If asymptomatic, no specific treatment besides rest may be given,” Watson says. If the heart function is severely damaged, then treatment consists of:

— Supporting the heart, which may include medication or require advanced therapies such as mechanical circulatory support.

— Controlling the inflammation, often with powerful anti-inflammatory medications like steroids.

— Protecting the heart with medications such as ACE inhibitors or beta blockers.

Prevention, of course, is the best medicine, and the widely available vaccines are your best way to do that. In addition, wearing a mask, practicing social distancing, washing your hands often and getting a flu shot to reduce the risk of a co-infection can also reduce your risk of contracting COVID-19 and potentially myocarditis.

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What to Know About Myocarditis originally appeared on usnews.com

Update 07/23/21: This story was published at an earlier date and has been updated with new information.

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