Covid-19 vaccination or infection: what are the real risks of myocarditis?

Covid vaccination is accused of causing myocarditis, and this risk is even scientifically proven. However, it is now also known that among athletes who contracted Covid-19, some also developed myocarditis. This cardiac consequence, when linked to intense effort, can be fatal. What exactly is this pathology, and is it better to be vaccinated or to catch the virus to limit the risks?

By Jean-François Tatard – Photos: Depositphotos.com / Creative Commons / JF Tatard

The objective of this article is to warn 3bikes.fr readers that myocarditis, which is very often caused by a viral infection, is also one of the potential sequelae of coronavirus, and to check if a link can also be made with vaccination. What worries us is that myocarditis is a frequent cause of sudden death in athletes.

A diagnosis of myocarditis made before it is too late will result in a cessation of sports practice for a period usually ranging from three to six months. We have a recent example with the Italian rider Diego Ulissi, who was diagnosed with myocarditis in December 2020 (i.e., before the start of the vaccination campaign) and had to interrupt training until the end of February, then competition in April. This did not prevent him from winning four victories during the 2021 season.

What is myocarditis?

The term “myocarditis” literally means “inflammation of the heart muscle.” There are several causes of myocarditis, whether infectious, toxic, allergic, or associated with another cardiovascular disease. In the vast majority of cases, myocarditis is caused by a viral infection that attacks heart muscle cells, such as Coxsackievirus or Adenovirus family viruses.

The symptoms of myocarditis are often non-specific and can be confused with those of the flu: fatigue, general weakness, joint pain, chest pain, palpitations, or other heart rhythm disorders. Depending on the stage of the infection, symptoms can be very variable. They can range from simple flu-like manifestations to arrhythmia, heart failure, or even the patient’s death.

Post-Covid myocarditis and post-vaccination myocarditis

The risk of developing myocarditis is highlighted after the injection of Pfizer and Moderna Covid-19 vaccines (more particularly with the latter), especially in boys and young people under 30. Indeed, since July 2021, myocarditis has been considered an adverse effect that can occur after vaccination against Covid-19 with an mRNA vaccine. However, this risk is also high after infection with the disease itself, according to a study by the CDC (Centers for Disease Control and Prevention) in the United States, which analyzed consultation data from more than 900 hospitals.

According to these data, the risk of hospitalization for myocarditis increases in the seven days following vaccination in men under 30, particularly after the second dose of Moderna, with an excess of about 132 cases per million doses in this population group. For the Pfizer vaccine, the excess cases observed would be about 27 per million doses in the same age group. In women under 30, there is an excess of 4 cases per million for Pfizer, and 37 for Moderna.

Furthermore, this study reports that in 2020, the number of consultations for myocarditis in these hospitals was 42% higher than in 2019, with peaks corresponding to those of the number of Covid-19 cases. This was before the vaccination campaign. An Israeli study published at the end of August in the scientific journal NEJM indicates that the risk of developing myocarditis after the injection of an mRNA vaccine (Pfizer) was multiplied by 3 compared to someone in perfect health, but that the risk associated with a Covid infection was multiplied by 18. The CDC concludes that myocarditis remains rare, with or without Covid-19. But the benefit-risk balance clearly favors vaccination in this case.

Post-infection investigations to detect a risk of myocarditis

After the disease, symptomatic or not, a medical investigation may yield normal results, yet the athlete may still have a cardiac abnormality that increases the risk of sudden death. So, to avoid this risk and try to circumvent this problem, the key is to make a gradual return after the illness, until maximum intensity is regained. Why not, for example, implement a questionnaire at the federation level, filled out by cyclists themselves? This would gather data on the nature, location, and duration of symptoms.

This collected information would then make it possible to determine whether the rider faces a mild, moderate, or severe risk of developing post-infectious complications. A patient who was asymptomatic or had a mild case should thus be evaluated to ensure that they do not have cardiac symptoms and that their physical examination is normal. And when cyclists have had more significant symptoms such as fever for several days or shortness of breath, it would be advisable to screen and perhaps even go as far as cardiac ultrasound. In case of doubt, a cardiac MRI would be performed to confirm or rule out the diagnosis of myocarditis. And if one wants to be 100% certain, a biopsy would be necessary, but this is a very invasive procedure that cannot be performed so easily.

Another thing that has been revealed is that in some patients who needed to be hospitalized: blood test results can determine if the heart has experienced some kind of stress or damage that could be myocarditis. These are not necessarily severe myocarditis cases, but there is something abnormal, which suggests that there has been damage.

In reality, we are navigating a gray area, where several elements must be taken into consideration in the diagnosis. If clinical suspicions suggest the need for an electrocardiogram, the results of this examination must be carefully analyzed and interpreted accordingly. The same electrocardiogram will be normal for an athlete who intensely practices their sport, but will be worrying if applied to someone aged 50 who has no physical activity or whose activity is exceptional.

Cardiac MRI is not perfect either. Sometimes anomalies unrelated to Covid-19 are detected, which prematurely halts the cyclist’s sports activity.

Prudence, whatever happens, means a gradual return to sport and a medical re-evaluation at the slightest symptom. Even if the risk is considered low in those who have had few or no symptoms, this risk can still be fatal.

And after vaccination?

The other question to ask is: should you stop playing sports for a while after vaccination, or is there a similar risk? In Belgium, there are reports of three cyclists who experienced cardiac problems after a second dose of the Pfizer vaccine. And even if the number remains almost anecdotal, in my opinion and that of the rest of the 3bikes.fr editorial team, it is better to reduce high-intensity sports activity for a few days after the injection.

The European Medicines Agency has listed the various symptoms: “shortness of breath, a strong heart rhythm that may be irregular (palpitations) and chest pain“. Health authorities recommend consulting a general practitioner if these symptoms appear. But the severity of these side effects is complex to establish. WHO experts, for their part, indicate that available data suggest that the immediate course of myocarditis (and pericarditis) after vaccination is generally mild and responds to treatment.

In conclusion, the link between myocarditis and Covid infection exists. It is rare but it exists. The link between vaccination and myocarditis is even rarer but it is also possible. So 3bikes.fr recommends all its readers to always take notes of their own sensations and perceptions. Whether post-infection or post-vaccination, we also recommend taking it easy on high-intensity sports for a week after the vaccine even if there are no symptoms. And finally, to resume sports very gradually, step by step, after a possible infection with regular check-ins.

=> SEE ALSO: All our Coaching articles