The global coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is still ongoing, with many institutions globally researching the pathogenesis of the disease. Complications associated with COVID-19 infection include myocardial injury and myocarditis, acute myocardial infarction, arrhythmias, heart failure and cardiomyopathy, and venous thromboembolism.¹Long B et al. Am J Emerg Med. 2020;38(7):1504-1507.  Acute cardiac injury, defined as a significant elevation in troponin levels, is also the most commonly reported cardiac abnormality in COVID-19, and viral involvement of cardiomyocytes seems to be the most common mechanism for cardiac injury.²Bansal M. Diabetes Metab Syndr. 2020;14(3):247-250.

While SARS-CoV2 has been previously reported to exist in lung tissue in a 78-year-old patient who died of unexpected cardiac arrest when ready for discharge after COVID-19 hospitalisation,³Yao X-H et al. Cell Res. Published online April 28, 2020:1-3. recently the first evidence of SARS-CoV2 infection in heart muscle cells has been reported in a case from Brazil and which is supported by evidence from other reports.^4,5Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).
Topol EJ, Science 10.1126/science.abe2813 (2020).

The patient in the case from Brazil was an 11-year-old child with COVID-19 related multisystem inflammatory syndrome in children (MIS-C), which is distinct from Kawasaki Disease, and who developed cardiac failure and died one day after hospital admission for treatment.^4,6Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).
Ebina-Shibuya R et al. Int J Infect Dis. 2020 Aug; 97: 371–373. The patient presented to the intensive care unit (ICU) with tachypnoea, hypoxia, and signs of congestive heart failure including jugular vein distention and crackles at the base of the lungs, displaced liver and hypotension, and was admitted for cardiovascular shock and persistent fever.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).  Her initial symptoms were fever for seven days, odynophagia, myalgia, and abdominal pain.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). The patient was intubated, and antibiotic treatment with ceftriaxone and azithromycin was initiated.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).

The patient was put on a mechanical ventilator during her first hour in the ICU, and her ventilatory parameters reached a maximum positive end-expiratory pressure of 8cm H₂O and peak inspiratory pressure of 25cm H₂O, with an initial fraction of inspired oxygen of 60%.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). The patient also had sinus tachycardia during her hospital stay and progressed to hyperdynamic vasoplegic shock refractory to volume resuscitation and vasoactive agents.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). The patient developed ventricular fibrillation 28 hours into her hospital admission and died.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).

A minimally invasive autopsy guided by ultrasound was performed, and tissue samples of the heart, lungs, liver, spleen, kidneys, brain, inguinal lymph node, quadriceps muscle, and skin were obtained.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). Histopathological examination of the heart showed myocarditis, pericarditis, and endocarditis that was characterised by inflammatory cell infiltration.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).

Electron microscope analysis of the sampled cardiac tissue showed spherical viral particles of 70-100nm in diameter, which was consistent in shape and size with viruses of the Coronaviridae family. These viral particles were found in the extracellular compartment and within cardiomyocytes, capillary endothelial cells, endocardium endothelial cells, macrophages, neutrophils, and fibroblasts.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).  SARS-CoV2 RNA was also detected on a postmortem nasopharyngeal swab and in cardiac and pulmonary tissues by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).

The findings of SARS-CoV2 in heart tissue indicate that myocardial inflammation was likely a primary response to the virus-induced injury to cardiac cells.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). This case demonstrates that viral particles can infect the different cell lineages of the heart. Such presence suggests potential mechanisms for heart damage.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). The doctors hypothesised that infection of cardiomyocytes likely led to local inflammation in response to cell injury, which is supported by the finding of viral particles in neutrophils.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0). Both virus-induced injury and inflammatory response could lead to cardiomyocyte necrosis.⁴Dolhnikoff M et al. Lancet Child Adolesc Health. 2020;0(0).