COVID-19 vaccine-associated myocarditis milder, confirms Cardiac MRI based study

Canada: Cardiac MRI shows the presence of a similar pattern of myocardial injury in myocarditis associated with the COVID-19 vaccine compared to myocarditis caused by other factors, says a recent study in the journal Radiology. Abnormalities although were found to be less severe, with no adverse events, and less frequent septal involvement over short-term follow-up. 

Myocarditis is a non-ischemic inflammatory disease of the heart muscle (myocardium), with diverse causes, clinical patterns, and outcomes. Myocarditis after immunization is a rare occurrence that recently has received increased attention recently due to reports of myocardial injury in a minority of patients who received messenger RNA (mRNA) based COVID-19 vaccines. However, there is not much data on the pattern and severity of myocardial injury in patients with COVID-19 vaccination-associated myocarditis.

Against the above background, Matteo Fronza, Department of Medical Imaging, Women's College Hospital, University of Toronto, Toronto, and colleagues aimed to describe myocardial injury following COVID-19 vaccination compared these findings to other causes of myocarditis in a retrospective cohort study. 

The study included consecutive adult patients with myocarditis with at least one T1-based and at least one T2-based abnormality on cardiac MRI performed at a tertiary referral hospital between 2019-2021. Patients were categorized into three groups: myocarditis following COVID-19 vaccination, myocarditis following COVID-19 illness, and other myocarditis not associated with COVID-19 vaccination or illness.