Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection often leads to pulmonary complications. Cardiovascular sequelae, including myocarditis and heart failure, have also been reported. Here, the study presents two fulminant myocarditis cases infected by SARS-CoV-2 exhibiting remarkable elevation of cardiac biomarkers without significant pulmonary injury, as determined by imaging examinations. Immunohistochemical staining reveals viral antigen within cardiomyocytes, indicating that SARS-CoV-2 could directly infect myocardium. The full viral genomes from respiratory, anal, and myocardial specimens are obtained via next-generation sequencing. Phylogenetic analyses of the whole genome and spike gene indicate that viruses in the myocardium/pericardial effusion and anal swabs are closely related and cluster together yet diverge from those in the respiratory samples. In addition, unique mutations are found in the anal/myocardial strains compared to the respiratory strains, suggesting tissue-specific virus mutation and adaptation. These findings indicate genetically distinct SARS-CoV-2 variants have infiltrated and disseminated within myocardial tissues, independent of pulmonary injury, and point to different infection routes between the myocardium and respiratory tract, with myocardial infections potentially arising from intestinal infection. These findings highlight the potential for systemic SARS-CoV-2 infection and the importance of a thorough multi-organ assessment in patients for a comprehensive understanding of the pathogenesis of COVID-19.

中文翻译：

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SARS-CoV-2 感染引起的暴发性心肌炎，无严重肺部受累：深入了解 COVID-19 发病机制

严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 感染通常会导致肺部并发症。心血管后遗症，包括心肌炎和心力衰竭，也有报道。在此，该研究介绍了两例 SARS-CoV-2 感染的暴发性心肌炎病例，根据影像学检查确定，心脏生物标志物显着升高，但没有明显的肺损伤。免疫组织化学染色显示心肌细胞内的病毒抗原，表明 SARS-CoV-2 可以直接感染心肌。通过下一代测序获得了呼吸道、肛门和心肌样本的完整病毒基因组。全基因组和刺突基因的系统发育分析表明，心肌/心包积液和肛门拭子中的病毒密切相关并聚集在一起，但与呼吸道样本中的病毒有所不同。此外，与呼吸道病毒株相比，在肛门/心肌病毒株中发现了独特的突变，表明组织特异性病毒突变和适应。这些发现表明，遗传上不同的 SARS-CoV-2 变体已在心肌组织内渗透和传播，与肺损伤无关，并指出心肌和呼吸道之间的感染途径不同，心肌感染可能由肠道感染引起。这些发现强调了系统性 SARS-CoV-2 感染的可能性，以及对患者进行彻底的多器官评估对于全面了解 COVID-19 发病机制的重要性。