ABSTRACT
Myocarditis can lead to myocardial infarction in the absence of coronary artery obstruction. We report a case of probable myocarditis, complicated by myocardial infarction with non-obstructive coronary arteries. A 19-year-old man presented with chest pain typical of myocarditis. He was a smoker but was otherwise well. Electrocardiogram revealed diffuse ST-elevation and echocardiography revealed a thin, akinetic apex. Troponin-T levels on admission were raised leading to an initial diagnosis of myocarditis being made. However, late gadolinium enhancement study on cardiac magnetic resonance imaging demonstrated transmural enhancement typical of ischaemia. Coronary angiogram was normal, leading to a likely diagnosis of myocardial infarction with non-obstructive coronary arteries. It is important to highlight that coronary assessment remains important when working up for myocarditis, as myocardial infarction with non-obstructive coronary arteries can often complicate myocarditis in cases of normal angiography. Another important lesson was on how cardiac magnetic resonance imaging provided vital evidence to support underlying ischaemia despite normal coronary angiogram, leading to a diagnosis of myocardial infarction with non-obstructive coronary arteries. Myocardial infarction with non-obstructive coronary arteries remains a broad 'umbrella' term and cardiac magnetic resonance imaging, as well as more invasive coronary imaging techniques during angiography, can further assist in its diagnosis. Our case provides a reminder that myocardial infarction with non-obstructive coronary arteries, although increasingly recognised, remains under-diagnosed and can often overlap with peri-myocarditis, highlighting the need to employ multi-modality imaging in guiding management.Copyright © The Author(s) 2021.
ABSTRACT
Objective: Severe acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) seen in SARs-CoV-2 infection has been attributed to the disruption of the immune response in COVID-19 patients. Neutrophilia and marked lymphocyte reductions are associated with disease severity and seem predictive of disease outcome in moderate and severe COVID-19 patients. Herein, we aim to decipher possible mechanisms involved in extensive tissue injury observed in COVID-19 patients, accompanied by vasculopathy, coagulopathy, and a high incidence of thrombotic complications in severe patients. Method(s): We searched PubMED for keywords including COVID-19 pathogenesis, thrombosis, and vasculities. Result(s): Neutrophils can undergo a specialized form of apoptosis to yield thread-like extracellular structures termed neutrophil extracellular traps (NETs), termed NETosis, which form web-like scaffolds of DNA, histones, and toxic protein granules and enzymes, whose primary function is to trap and eliminate microbes. However, uncontrolled NET production can lead to ALI and ARDS, coagulopathy, multiple organ failure, and autoimmune disease. Dysregulation of NETs promotes production of anti-neutrophil cytoplasmic antibodies (ANCA) which affects small vessels through ANCA-associated vasculitis (AAV). Furthermore, NETs can also induce thrombosis via formation of scaffolds that trap platelets, RBCs, fibronectin, and other proteins, which can also induce coagulation. Conclusion(s): We suggest that NET production is central during SARS-CoV-2 infection and COVID-19 pathogenesis, associated with alveolar damage accumulation of edema, endothelial injury and coagulopathy, elevated platelet activation and thrombogenesis forming a NET production feed-forward loop, causing diffuse small vessel vasculitis in the lungs and other organs. Copyright © 2020 FSG Communications Ltd. All rights reserved.