Incremental Value of Cardiac MRI in Patients Suspected to Have Myocarditis Following COVID-19 mRNA Vaccination

Abstract

Myocarditis post MRNA based COVID-19 vaccination remains a community concern. This usually occurs in young males within 7 days post. We aimed to review local data for presentations of this including investigations and clinical outcomes. We performed a search of the cardiac MRI database for studies including the words “vaccine”, “Pfizer”, “Moderna” and “mRNA” alone and in combination. All cardiac MRIs were reviewed, and those with no evidence of myocardial or pericardial inflammation were excluded. The cases were then reviewed. Between February 2020 to February 2022, 14 cases were identified with MRI confirmed myocarditis post COVID-19 vaccination. 3 cases were deemed unlikely to be attributable to the vaccination. Of the remaining 11 patients, 7/11 (64%) were male, with a mean age of 20 years. Most had no significant medical history. 8/11 (73%) occurred after the second dose with a median onset of 3 days post vaccination. Chest pain (100%), dyspnoea (18%) and fevers (18%) were the most common presenting complaints. The mean peak troponin level was 7869 ng/L, mean CRP was 22.57 mg/L. 6/11 (54%) of had ECG abnormalities, widespread ST elevation was most common (37%). Transthoracic echocardiography was normal for most 9/11 (81.8%). Lateral wall subepicardial late gadolinium enhancement was the most common MRI finding. Mean LOS was 2.64 days. There were no readmissions. In keeping with international data, most cases were young, male, and after dose two. Most cases had normal TTE. Lateral wall LGE was the most common MRI finding. Most cases were clinically mild, with short LOS.