Myocarditis and inflammatory cardiomyopathy: current evidence and future directions.

Inflammatory cardiomyopathy, characterized by inflammatory cell infiltration into the myocardium and a high risk of deteriorating cardiac function, has a heterogeneous aetiology. Inflammatory cardiomyopathy is predominantly mediated by viral infection, but can also be induced by bacterial, protozoal or fungal infections as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Despite extensive research, inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. At present, the reason why some patients recover without residual myocardial injury whereas others develop dilated cardiomyopathy is unclear. The relative roles of the pathogen, host genomics and environmental factors in disease progression and healing are still under discussion, including which viruses are active inducers and which are only bystanders. As a consequence, treatment strategies are not well established. In this Review, we summarize and evaluate the available evidence on the pathogenesis, diagnosis and treatment of myocarditis and inflammatory cardiomyopathy, with a special focus on virus-induced and virus-associated myocarditis. Furthermore, we identify knowledge gaps, appraise the available experimental models and propose future directions for the field. The current knowledge and open questions regarding the cardiovascular effects associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also discussed. This Review is the result of scientific cooperation of members of the Heart Failure Association of the ESC, the Heart Failure Society of America and the Japanese Heart Failure Society.

Modulation of the acute defence reaction by eplerenone prevents cardiac disease progression in viral myocarditis.

AIMS: Left ventricular (LV) dysfunction in viral myocarditis is attributed to myocardial inflammation and fibrosis, inducing acute and long-time cardiac damage. Interventions are not established. On the basis of the link between inflammation, fibrosis, aldosterone, and extracellular matrix regulation, we aimed to investigate the effect of an early intervention with the mineralocorticoid receptor antagonist (MRA) eplerenone on cardiac remodelling in a murine model of persistent coxsackievirus B3 (CVB3)-induced myocarditis. METHODS AND RESULTS: SWR/J mice were infected with 5 × 104 plaque-forming units of CVB3 (Nancy strain) and daily treated either with eplerenone (200 mg/kg body weight) or with placebo starting from Day 1. At Day 8 or 28 post infection, mice were haemodynamically characterized and subsequently sacrificed for immunohistological and molecular biology analyses. Eplerenone did not influence CVB3 load. Already at Day 8, 1.8-fold (P < 0.05), 1.4-fold (P < 0.05), 3.2-fold (P < 0.01), and 2.1-fold (P < 0.001) reduction in LV intercellular adhesion molecule 1 expression, presence of monocytes/macrophages, oxidative stress, and apoptosis, respectively, was observed in eplerenone-treated vs. untreated CVB3-infected mice. In vitro, eplerenone led to 1.4-fold (P < 0.01) and 1.2-fold (P < 0.01) less CVB3-induced cardiomyocyte oxidative stress and apoptosis. Furthermore, collagen production was 1.1-fold (P < 0.05) decreased in cardiac fibroblasts cultured with medium of eplerenone-treated vs. untreated CVB3-infected HL-1 cardiomyocytes. These ameliorations were in vivo translated into prevention of cardiac fibrosis, as shown by 1.4-fold (P < 0.01) and 2.1-fold (P < 0.001) lower collagen content in the LV of eplerenone-treated vs. untreated CVB3-infected mice at Days 8 and 28, respectively. This resulted in an early and long-lasting improvement of LV dimension and function, as indicated by reduced LV end-systolic volume and end-diastolic volume, and an increase in LV contractility (dP/dtmax ) and LV relaxation (dP/dtmin ), respectively (P < 0.05). CONCLUSIONS: Early intervention with the MRA eplerenone modulates the acute host and defence reaction and prevents cardiac disease progression in experimental CVB3-induced myocarditis without aggravation of viral load. The findings advocate for an initiation of therapy of viral myocarditis as early as possible, even before the onset of inflammation-induced myocardial dysfunction. This may also have implications for coronavirus disease-19 therapy.