Cardiac MRI indicates that myocarditis associated with the COVID-19 vaccine shows a similar pattern compared to myocarditis caused by other factors, but is milder, according to a study published February 15 in Radiology.
Myocarditis is inflammation of the heart muscle and can be caused by viral infections. It has been reported as a complication of mRNA-based COVID-19 vaccines.
Since cardiac MRI is typically used to assess myocarditis, a team led by Dr. Matteo Fronza of the University of Toronto in Canada sought to investigate the pattern and extent of myocarditis findings in individuals who had been vaccinated for COVID-19.
The team conducted a study that included 92 adults with myocarditis and abnormalities on cardiac MRI. Patients were categorized as follows:
- Those who developed myocarditis after COVID-19 vaccination
- Those who developed myocarditis after COVID-19 illness
- Those who developed myocarditis due to non-COVID-19 factors
Fronza's group found that 22% of the patients had myocarditis after receiving the COVID-19 vaccine, while 11% had the condition after being ill with COVID-19 and 66% developed it from non-COVID-19 causes.
But the abnormal cardiac MRI findings were less severe in patients with myocarditis after receiving the COVID-19 vaccine, while those who developed the condition after COVID-19 illness or via other causes had a "higher prevalence of abnormalities involving the interventricular septum and worse myocardial injury measured by T1 mapping," the investigators noted.