Myocarditis and how to think about it… like a cardiologist

There may be multiple articles on the internet that discuss myocarditis following COVID vaccination. These articles should make you aware of your options and what to do if it occurs. Myocarditis diagnosis can be complicated. I, a board-certified pediatric cardioologist, want to share some of the nuance with you.

This article will be about myocarditis from the perspective a mainstream pediatric cardiologist. For excellent articles on postvaccine myocarditis research and statistics, I refer to the previously published Science Based Medicine work by Dr. David Gorski and Dr. Dan Freedman and Dr. Jonathan Howard.

Numerous news outlets have made the argument that COVID vaccination myocarditis can be worse than COVID-related myocarditis. First, let's define what this statement means. There are many types of tissue in the heart muscle, including connective tissue (scaffolding), muscle (the workhorse), nervous tissue (the communications network), nerve tissue and electrical tissue. These tissues also include vascular tissue (to keep everything nourished). At the core of myocarditis is inflammation of your heart. Myocarditis can be caused by many different factors. Because myocarditis is most often seen in young children and adolescents, I will concentrate my discussion on this group. Older adults have a much better risk-benefit ratio.

Myocarditis can be caused by many things, but most children get it from being exposed to some type of virus. These are just a few of the causes (citation European Society of Cardiology).

Myocarditis is usually diagnosed in a hospital or cardiology office. The following case description by the Centers for Disease Control and Prevention, with small regional variations, has been used:

Non-medical readers can find it quite disconcerting to see the cases of myocarditis reported. Naturally, the next question is why did not the mRNA platform vaccine be halted as soon as all these cases of myocarditis became known? Right after the discovery that vaccine-induced thrombotic hemorhagepenia was possible, the adenoviral vector vaccine platform was halted. You may not remember any other details, but not all myocarditis are the same severity. Why did myocarditis not feature in the core clinical trials of myocarditis? The reason it didn't happen was that the researchers were not looking. It was because of a concept called study power. A fluorescent needle cannot be found in one in 100 000 haystacks. This means that many haystacks will need to be searched in order to find the needle. The search becomes much easier if the needle is located in 1/50 of the haystacks.

Myocarditis, of any cause, is a common condition that has been reported in the past at 1-2/100,000. (citation: Moss & Adams Heart Disease in Infants). Myocarditis has historically been more common in men than it was in women. Troponin is a common component of the heart muscle and is the classic blood test to diagnose myocarditis. Troponin is not a normal component of the heart muscle. This is why it is important to not label every patient with troponin in their blood as myocarditis. (citation American College of Cardiology).

It is the role of a cardioologist to determine if a patient has myocarditis. Sometimes, it can be hard to diagnose myocarditis. Patients don't always follow the rules of medicine. Patients rely on us to find out why their body is acting in a certain way. They don't always fit the traditional criteria that medical school taught them to look for. If the diagnosis is not clear, radiologists who specialize in cardiac MRI or cardiologists can help to image the heart. (Image citations UCDavis, Cardiologists can confirm diagnosis using specialized MRI criteria.

To determine the severity of an illness, cardiologists can combine the EKG, echocardiogram, laboratory tests and cardiac MRI (if it is available) with how the patient is acting. Some hospitals do not offer cardiac MRI. Sometimes, you might see a cardiologist using other tools in the hospital toolkit. A description of the severity of each must be included in any discussion about COVID vaccine myocarditis and COVID disease myocarditis. Without this information, the discussion could easily become misleading. What do we know so far about these two?

It is difficult to determine the true incidence of viral myocarditis caused by seasonal viruses in young men, but it is likely higher than those numbers. What is the reason? Why? Because every patient who has a sniffle does not see a doctor to determine if they have myocarditis. It is reasonable to compare the depth of your testing with the severity. Viral myocarditis can be symptom-free or require life support. SARS-COV2 viral marrow myocarditis is similar.

How high is the incidence of viral myocarditis (COVID19) in teenage girls and boys, the group most at-risk for post-vaccine myocarditis. This study from Cleveland using the TriNetX Research network showed that 876 boys developed myocarditis in COVID19. These rates were split into 12-15 and 16-19. The respective rates were 601 per million and 561 per mil, respectively. The rates for girls were 213 per one million, 235 per million, 708 per million, and 213/million in the age group of 12-15 and 16-19, respectively. The same study found that myocarditis is six times more common after infection than after vaccination. This 2nd article (Safety and Use of the BNT162b2 mRNA Covid-19 Vaccine) compared side effects of COVID vaccination to older patients (albeit in an older age bracket). It found that the incidence of side effects in patients infected by the real virus was higher than in those who received vaccination. The vaccination also poses an increased risk of developing myocarditis beyond the baseline. Myocarditis from COVID is worse than myocarditis from COVID vaccine.

Hoeg et. al.'s now-famous study is misleading. Their core premise states that vaccination myocarditis is more common in people who have COVID disease than in people who get it. This is the surprising conclusion that you will reach if you only look at VAERS reports and do not perform any analysis. In fact, VAERS specifically warns readers not to use their database this way. It is intended to be used as a tool for creating hypotheses but not to search causality. This problem can be better researched using databases such as the Vaccine Safety Datalink. To be as precise as possible and to ensure that all cases are accurately estimated, the Centers for Disease Control and Prevention uses very specific criteria for myocarditis (which is consistent with what most cardiologists use).

Myocarditis is not something I want to minimize. If I was to see a COVID-vaccine myocarditis patient who was seriously ill, I would make it public and warn everyone about the dangers. I have never met such a patient and all patients in my clinic have recovered. My entire clinic, which includes all my cardiologist partners and me, has seen approximately five COVID vaccine myocarditis patients. Similar questions were made to my colleagues, who all agreed that they are all symptomatically healing. Although the study did not collect many MRIs before publication, the study group will continue to conduct a follow up work that includes MRI studies. My patients who have suffered from post-COVID vaccination myocarditis are seeing cardiac MRIs which look very, very reassuring. There are some unpublished data that shows patients who had extremely concerning cardiac MRIs following COVID vaccination. These patients have cardiologists who closely monitor them. These patients are being monitored by a special study group that has been established by the CDC. This is not an attempt to minimize myocarditis.

While I support any efforts to reduce the risk of mRNA vaccine myocarditis, given the rapid growth of Pediatric Intensive Care Admissions (PICU), I would not be in favor of any attempt to do so at the expense of vaccination efficacy, or even at the cost to add PICU admissions. Even if they don't cause long-term complications, PICU admissions can be a major hit on a teenagers quality life. I am grateful for the work of Professor Shane Crottys team in clarifying the relative effectiveness and post-immunization immunity. I look forward to the discussion by the Immunology community on this topic. Although I can't speak for them, I will be glad to refer you to their research. The risk of COVID vaccine-related myocarditis is higher than that of vaccination with other classical vaccines. However, the absolute risk remains very low. Each patient with this condition may be seen by a pediatric cardiologist who is available to provide the appropriate care. You are taking a substantial risk in exchange for a smaller, more calculated risk.