Fulminant myocarditis in the time of coronavirus

The role of NETosis in heart failure

The hallmark of heart failure (HF) is structural myocardial remodeling including cardiomyocyte hypertrophy, fibrosis, cardiomyocyte cell death, and a low-grade aseptic inflammation. The initiation and maintenance of persistent chronic low-grade inflammation in HF are not fully understood. Oxidative stress-mediated neutrophil extracellular traps (NETs) are the main immune defense mechanism against external bacterial infections. Furthermore, NETs play important roles in noninfectious diseases. In the settings of myocardial infarction, myocarditis, or cardiomyopathies, neutrophils infiltrate the cardiac tissue and undergo NETosis that further aggravate the inflammation. A number of stimuli may cause NETosis that is a form of programmed cell death of neutrophils that is different from apoptosis of these cells. Whether NETosis is directly involved in the pathogenesis and development of HF is still unclear. In this review, we analyzed the mechanisms and markers of NETosis, especially placing the accent on the activation of the neutrophil-specific myeloperoxidase (MPO), elastase (NE), and peptidylarginine deiminase 4 (PAD4). These conclusions are supported by the recent genetic and pharmacological studies which demonstrated that MPO, NE, and PAD4 inhibitors are effective at least in the settings of post-myocardial infarction adverse remodeling, cardiac valve diseases, cardiomyopathies, and decompensated left ventricular hypertrophy whose deterioration can lead to HF. This is essential for understanding NETosis as a contributor to pathophysiology of HF and developments of new therapies of HF.

Clinical variants of myocardial involvement in COVID-19-positive patients: a cumulative experience of 2020

Myocardial injury, diagnosed by troponin elevation, is common in COVID-19 patients, but cardiac involvement with clinical manifestations occurs less frequently. We analyzed the literature on COVID-19 (2020) and systematically reviewed the cases where individual patient data were presented. We searched PubMed and Google Scholar for "COVID," "COVID-19," and "coronavirus" in combination with "myocarditis," "heart failure," "takotsubo," "cardiomyopathy," and "cardiogenic shock." We identified 90 cases of COVID-19 with myocardial involvement, mean age 52.9 ± 18.3 years, 54.5% males. Of them, 55 survived (61.1%), 20 died (22.2%), and in 15 (16.7%) the outcome was unknown at the time of publication. Among patients with known outcome, mortality was 26%. The nadir LVEF was 31.7 ± 13.1% and recovered to 50.1 ± 16.0%. Pericardial effusion was a common finding, reported in 21 (23.3%) of patients, including moderate size effusion in 8.9% and large in 7.8%. The effusion caused tamponade in 11 (12.2%) of patients. Out of 83 patients who experienced a decrease in LVEF, 30 could be classified as takotsubo syndrome. The takotsubo patients were older than those with myocarditis, and with relatively high proportion of males. About one third of the cases was complicated by cardiogenic shock. Myocardial involvement in COVID-19 patients most often presents as a new, rapid decrease in LVEF, although normal LVEF or takotsubo-like wall motion pattern does not rule out myocarditis. Moderate and large pericardial effusion is common, and cardiac tamponade occurs in 12.2% of patients. Cardiogenic shock develops in one third of the patients. Mortality appears to be high at 26%.

Ex uno, plures-From One Tissue to Many Cells: A Review of Single-Cell Transcriptomics in Cardiovascular Biology

Recent technological advances have revolutionized the study of tissue biology and garnered a greater appreciation for tissue complexity. In order to understand cardiac development, heart tissue homeostasis, and the effects of stress and injury on the cardiovascular system, it is essential to characterize the heart at high cellular resolution. Single-cell profiling provides a more precise definition of tissue composition, cell differentiation trajectories, and intercellular communication, compared to classical bulk approaches. Here, we aim to review how recent single-cell multi-omic studies have changed our understanding of cell dynamics during cardiac development, and in the healthy and diseased adult myocardium.

Immune Mechanisms in Cardiovascular Diseases Associated With Viral Infection

Influenza virus infection causes 3-5 million cases of severe illness and 250,000-500,000 deaths worldwide annually. Although pneumonia is the most common complication associated with influenza, there are several reports demonstrating increased risk for cardiovascular diseases. Several clinical case reports, as well as both prospective and retrospective studies, have shown that influenza can trigger cardiovascular events including myocardial infarction (MI), myocarditis, ventricular arrhythmia, and heart failure. A recent study has demonstrated that influenza-infected patients are at highest risk of having MI during the first seven days of diagnosis. Influenza virus infection induces a variety of pro-inflammatory cytokines and chemokines and recruitment of immune cells as part of the host immune response. Understanding the cellular and molecular mechanisms involved in influenza-associated cardiovascular diseases will help to improve treatment plans. This review discusses the direct and indirect effects of influenza virus infection on triggering cardiovascular events. Further, we discussed the similarities and differences in epidemiological and pathogenic mechanisms involved in cardiovascular events associated with coronavirus disease 2019 (COVID-19) compared to influenza infection.