Myocarditis and Pericarditis following COVID-19 mRNA Vaccination: Practical Considerations for Care Providers

Luk, Adriana; Clarke, Brian; Dahdah, Nagib; Ducharme, Anique; Krahn, Andrew; McCrindle, Brian; Mizzi, Trent; Naus, Monica; Udell, Jacob A; Virani, Sean; Zieroth, Shelley; McDonald, Michael

The mRNA vaccines against COVID-19 infection have been effective in reducing the number of symptomatic cases worldwide. With widespread uptake, case series of vaccine-related myocarditis/pericarditis have been reported, particularly in adolescents and young adults. Males tend to be affected with greater frequency, and symptom onset is usually within one week following vaccination. Clinical course appears to be mild in the overwhelming majority of cases. Based on the available evidence, we highlight a clinical framework to guide providers on how to assess, investigate, diagnose and report suspected and confirmed cases. In any patient with highly suggestive symptoms temporally related to COVID-19 mRNA vaccination, standardized work-up includes serum troponin measurement and PCR testing for COVID-19 infection, routine additional labwork, and a 12-lead ECG. Echocardiography is recommended as the imaging modality of choice for patients with unexplained troponin elevation and/or pathologic ECG changes. Cardiovascular specialist consultation and hospitalization should be considered based on the results of standard investigations. Treatment is largely supportive, and myocarditis/pericarditis that is diagnosed by defined clinical criteria should be reported to Public Health authorities in every jurisdiction. Finally, we recommend COVID-19 vaccination in all individuals in accordance with the Health Canada and NACI guidelines. In patients with suspected myocarditis/pericarditis following the 1(st) dose of an mRNA vaccine, deferral of 2(nd) dose is recommended until additional reports become available. With widespread uptake of COVID-19 mRNA vaccines, reports of vaccine-related myocarditis/pericarditis have emerged. Based on the available evidence, we highlight a clinical framework to guide providers on how to assess, investigate, diagnose and report suspected and confirmed cases. We recommend COVID-19 vaccination in all individuals in accordance with the Health Canada and NACI guidelines. For patients with suspected myocarditis/pericarditis following the 1(st) dose of mRNA vaccine, deferral of 2(nd) dose is recommended pending further data.