Acute Myocarditis Following mRNA-1273 SARS-CoV-2 Vaccination

Canada, 8 July 2021, Williams et al, CJC Open


A case report of acute perimyocarditis in a young (34 year old), healthy man after vaccination with the mRNA-1273 (SARS-CoV-2; Moderna) vaccine. He presented with chest pain and decompensated heart failure 3 days after administration of his second dose.

On physical exam, he was febrile (39.1oC), tachycardic with a heart rate of 102, had blood pressure of 103/67 mm Hg, and was tachypneic, with a respiratory rate of 28 and oxygen saturation of 93% on room air. His jugular venous pressure was elevated, he had no murmurs or rubs, and he had mild crackles to the lung bases. Electrocardiography showed lateral PR-segment depression and ST-segment elevation mirrored in the aVR with PR-segment elevation and ST-segment depression (Fig. 1 ). Laboratory investigation on admission showed a high-sensitivity troponin T concentration of 4026 ng/L (normal < 14 ng/L), which peaked at 5203 ng/L; N-terminal pro-B-type natriuretic peptide [NT-proBNP] concentration of 1551 ng/L (normal < 125 ng/L); a white blood cell count of 8.4 x 109/L; lactate level at 1.1 mmol/L, and a C-reactive protein level of 111 mg/L. Sputum and blood cultures were negative, and nasopharyngeal coronavirus disease 2019 (COVID-19) polymerase chain reaction was nonreactive. Chest radiograph revealed mild pulmonary edema. His symptoms, physical exam, and investigations were suspicious for perimyocarditis.

A transthoracic echocardiogram revealed reduced left ventricular ejection fraction (LVEF) of 43%, without pericardial effusion. Cardiac magnetic resonance imaging (MRI) performed on day 4 of admission showed normalization of the LVEF to 54%, with subepicardial late gadolinium enhancement in the anterolateral and inferolateral segments, as well as patchy myocardial edema on T2-weighted images (Fig. 2 ), meeting the Lake Louise criteria for myocarditis. The MRI also demonstrated pericardial enhancement consistent with inflammation, confirming the clinical suspicion of perimyocarditis.

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