Clinical characteristics and prognostic factors of myocarditis associated with the mRNA COVID-19 vaccine

Abstract

To analyze the clinical presentation and outcomes of myocarditis after administration of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccine. Nine case series and 15 case reports (74 patients) of myocarditis after administration of the BNT162b2 or mRNA-1273 vaccine were reviewed from PubMed, Scopus, Embase, and Web of Science. We analyzed clinical manifestations, diagnostic findings, and outcomes. In addition, we performed a pooled analysis and investigated risk factors leading to admission to the intensive care unit and recovery with conservative care. Most patients were male (94.6%), and the median age (range) was 17.6 (14-70) years. Patients who received the BNT162b2 (n = 58, 78.4%) vaccine presented fewer systemic symptoms and left ventricular dysfunction than mRNA-1273 recipients. Although patients under 20 years experienced more fever and myalgia, they had better ejection fraction and less prominent myocardial inflammation in magnetic resonance imaging than older patients. The clinical course of all patients was favorable without mortality, and one-third of patients resolved with conservative care alone. Risk factor analyses revealed that patients with gastrointestinal symptoms required intensive care (odds ratio: 20.3, 95% confidence interval 1.90-217, p = 0.013). The risk of fatality in myocarditis subjected to mRNA vaccination seems to be low. However, patients with gastrointestinal symptoms received more intensive care, and a significant proportion of patients recovered with conservative management.

Keywords: BNT162b2; COVID-19 vaccine; mRNA-1273; myocarditis; vaccine-induced myocarditis.

Figure 1

Correlation among key clinical characteristics and diagnostic findings with Phi(Φ) coefficient Tx, treatment; EF, ejection fraction; Hx, history; BNP, B‐type natriuretic peptide; HOD, hospital stay. *Cardiac MRI findings satisfying original or modified Lake Louise criteria. ^§Conservative care: patients who recovered without administration of anti‐inflammatory agents or cardiovascular medications. ^◻Treatment including colchicine, nonsteroidal anti‐inflammatory drugs, steroid, or intravenous immunoglobulin

Figure 2

Treatment outcome of myocarditis patients between COVID‐19 induced and COVID vaccine related *p < 0.05, **p < 0.001. ^†It accounts for cases that needed intubation, mechanical ventilation, or ECMO support. ^††It included patients who did not receive anti‐inflammatory agents, steroids, IV immunoglobulin, cardiovascular medications We compared the pooled data of 42 patients in two systematic reviews, of case reports about myocarditis due to COVID‐19 infection and our data of myocarditis patients who developed after mRNA vaccinations