key: cord-0867090-t3l1yycs authors: Williams, Curtis B; Choi, Jung-in; Hosseini, Farshad; Roberts, James; Ramanathan, Krishnan; Ong, Kevin title: Acute Myocarditis Following mRNA-1273 SARS-CoV-2 Vaccination date: 2021-07-14 journal: CJC Open DOI: 10.1016/j.cjco.2021.07.008 sha: 8b6f53798d440b056057514c14f1797fd1d49af0 doc_id: 867090 cord_uid: t3l1yycs Myocarditis has previously been described as a rare side effect of both influenza and smallpox vaccines. In this report, we present a case of acute perimyocarditis in a young, healthy male 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, and his symptoms resolved by 9 days post-inoculation. This case highlights a potentially rare but serious side effect of this mRNA vaccine that primary care physicians and cardiologists should be aware of in order to identify and appropriately manage these patients. We present a case of acute myocarditis in a young, healthy male after his second dose of the mRNA-1273 SARS-CoV-2 (Moderna) vaccine. The aim of this report is to highlight and raise awareness of a potential rare side effect of this vaccine that has not yet been described in the literature. Myocarditis has previously been described as a rare side effect of both influenza and smallpox vaccines. In this report, we present a case of acute perimyocarditis in a young, healthy male 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, and his symptoms resolved by 9 days post-inoculation. This case highlights a potentially rare but serious side effect of this mRNA vaccine that primary care physicians and cardiologists should be aware of in order to identify and appropriately manage these patients. A 34-year-old previously healthy male presented to the hospital with a 3-day history of fevers and myalgias and 2-day history of a dull, retrosternal chest pain that was both positional and pleuritic nature. He had received his second dose of the mRNA-1273 SARS-CoV-2 (Moderna) vaccine one day prior to his symptom onset. He took no medications, did not use any recreational drugs, and his infectious review of systems was otherwise negative. clinical, biochemical and LVEF improvement, an endomyocardial biopsy was deferred. He was discharged from the hospital symptom free on medical therapy with high dose aspirin, colchicine, bisoprolol and rampiril with a plan for close outpatient follow up. Myocarditis is an acute inflammatory disease of the myocardium predominantly associated with infectious agents (often viruses), toxic substances or systemic immune-mediated disorders. The gold standard for diagnosis is via histopathological sampling with endomyocardial biopsy, however, this is not always feasible or practical. A probable diagnosis can be achieved in the appropriate clinical context with elevated cardiac enzymes as well as functional and structural abnormalities on cardiac echocardiogram and MRI [1] . Vaccine related myocarditis is rare but has been documented with live-attenuated influenza and small-pox vaccines [2] [3] . The causality is uncertain, and mechanism is not fully understood, but there are some hypotheses that post-vaccine myopericarditis may be secondary to lymphocytic infiltration resulting in an immune mediated myocardial injury [3] . COVID-19 Vaccine mRNA-1273 developed by ModernaTx, Inc is a pre-fusion SARS-CoV-2 spike glycoprotein (S) antigen encoded in mRNA and formulated in lipid nanoparticles, representing a novel vaccination technology with ongoing surveillance for potential unrecognized side-effects. During the phase 3 study for this vaccine, no cases of myocarditis were documented in any of the 30,420 participants [4] . Cardiac involvement in COVID-19 infection is well recognized, with manifestations ranging from myocardial injury to cardiogenic shock. Myocarditis itself is a known complication of coronavirus disease [5] . With the global vaccination effort well underway and millions of mRNA vaccines administered, the potential for myocarditis after vaccination is being increasingly recognized in case series [6] [7] . Similar to our patient, most reported cases describe younger male patients presenting within days of their second vaccine dose who have a self-limited course without malignant arrythmias or need for advanced circulatory support [6] [7] . While this patient and others reported thus far have had a favourable course and outcome, recognition of this entity is important in managing these patients appropriately, and may have yet unknown future implications. The purpose of this case is to highlight a potential rare side effect of this vaccine for clinicians to be aware of, and not to deter clinicians and patients from the proven efficacy and overall safety profile of this mRNA vaccine.  Clinicians should be aware that patients presenting with chest pain after vaccination with mRNA vaccines (Moderna or Pfizer-BioNTech) may have myocarditis or perimyocarditis  The natural history of mRNA vaccine associated myocarditis is not known, but case reports suggest a favourable prognosis and rapid recovery  Myocarditis after mRNA vaccination appears to be rare, and the goal of this report is not to deter clinicians or patients from vaccination, but to raise awareness of this clinical Effect of acute immunosuppression on left ventricular recovery and mortality in fulminant viral myocarditis: A case series and review of literature. CJC Open Myocarditis and pericarditis after immunization Smallpox vaccination and myopericarditis: a clinical review Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine Recognizing COVID-19-related myocarditis Myocarditis after BNT162b2 and mRNA-1273 Vaccination. Circulation Myocarditis temporally associated with COVID-19 Vaccination. Circulation