MRI scan revealed the relationship between myocarditis and COVID vaccine

According to a new study published in the journal Radiology, vaccine-associated myocarditis has a comparable damage pattern on cardiac MRI to other types of myocarditis, but the abnormalities are less severe.

Myocarditis, or inflammation of the heart muscle, is a common complication of viral infections, such as COVID-19. It can alter the heart's rhythm and capacity to pump blood, as well as cause long-term damage to the heart muscle in the form of scarring. Myocarditis has also been reported as an uncommon side effect of COVID-19 vaccinations based on messenger RNA (mRNA).

Cardiac MRI plays a significant role in the diagnosis of acute myocarditis because of its unrivalled capacity to characterise cardiac tissue noninvasively. Understanding the pattern and amount of myocardial injury, as well as its consequences, may allow for better patient care and may help to overcome vaccine hesitancy.

As a result, University Health Network, University of Toronto, cardiac radiologist Kate Hanneman, M.D., M.P.H., and colleagues set out to determine the pattern and extent of cardiac MRI findings in myocarditis associated with COVID-19 vaccination, as well as compare these findings to other causes of myocarditis, including COVID-19.

"We know that the risk of myocarditis after receiving COVID-19 vaccine is quite minimal. However, compared to other causes of myocarditis, there is very little information on the extent of heart injury "Dr. Hanneman stated the following.

The researchers reviewed data from 92 adult patients with myocarditis and anomalies on cardiac MRI done at a tertiary referral hospital between 2019 and 2021 for this retrospective investigation. Myocarditis following COVID-19 vaccine, myocarditis following COVID-19 illness, and myocarditis not connected with COVID-19 immunisation or illness were the three groups of patients studied.

Following COVID-19 vaccination, 21 (22%) of the 92 individuals developed myocarditis (mean age 31 years). Following COVID-19 infection, ten individuals (11%) developed myocarditis (mean age 51 years), while 61 (66%) had other myocarditis (mean age 44 years). In comparison to the other groups, those who developed myocarditis after vaccination were younger and more likely to be male.

All 21 individuals with vaccine-associated myocarditis experienced chest discomfort. One to seven days after immunisation, the pain began and lasted one to six days. Fourteen patients (67%) were admitted to the hospital, with a median stay of three days. The intensive care unit did not receive any patients. Troponin levels were increased in all of the patients hospitalised to the hospital, but they had significantly dropped by the time they were discharged.

In vaccine-related myocarditis, MRI results included late gadolinium enhancement in 17 (81%) cases and left ventricular failure in 6 cases (29 percent ). Patients with vaccine-associated myocarditis had less functional impairment and less severe myocardial abnormalities than patients with other types of myocarditis, according to cardiac MRI. Patients with COVID-19 infection and other myocarditis showed a higher prevalence of interventricular septum anomalies and worse myocardial damage as determined by T1 mapping.

All patients with vaccine-associated myocarditis were asymptomatic and had no adverse outcomes after a short period of follow-up (median 22 days).

"These findings suggest that myocarditis caused by COVID-19 immunisation is usually moderate and recovers fast," Dr. Hanneman stated.

Matteo Fronza, M.D., first author and cardiac imaging fellow, remarked that the absence of adverse events and remission of all symptoms during follow-up were comforting. Longer-term follow-up is, however, required.

COVID-19 infection can cause cardiac damage, which has been linked to poor outcomes in hospitalised patients, according to the researchers, and this risk should be evaluated against the low risk of vaccine-related problems.

"Not only is myocarditis after COVID-19 immunisation uncommon, but it also tends to be milder than myocarditis after SARS-CoV2 infection," Dr. Hanneman added.

Reference:

Matteo Fronza, Paaladinesh Thavendiranathan, Victor Chan, Gauri Rani Karur, Jacob A. Udell, Rachel M. Wald, Rachel Hong, Kate Hanneman. Myocardial Injury Pattern at MRI in COVID-19 Vaccine–associated Myocarditis. Radiology, 2022; DOI: 10.1148/radiol.212559