Global alert and response network for hepatitis C virus-derived heart diseases: A call to action

Hepatitis C Virus-Associated Extrahepatic Manifestations in Lung and Heart and Antiviral Therapy-Related Cardiopulmonary Toxicity

Besides liver cirrhosis and hepatocellular carcinoma, chronic hepatitis C virus (HCV) infection is associated with many extrahepatic manifestations (EHMs). HCV exhibits lymphotropism that is responsible for various EHM. An important characteristic of HCV is escape from the immune system, which enables it to produce chronic infections and autoimmune disorders along with accumulation of circulating immune complexes. These EHMs have large spectrum, because they affect many organs such as heart, lungs, kidney, brain, thyroid, and skin. HCV-related cardiac and pulmonary manifestations include myocarditis, cardiomyopathies, cardiovascular diseases (i.e., Stroke, ischemic heart disease), chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, asthma, and interstitial lung diseases. This review discusses etiology and pathogenesis of HCV-associated cardiac and pulmonary manifestations and how different genes, immune system, indirectly linked factors (mixed cryoglobulinemia), liver cirrhosis, and antiviral treatment are involved in HCV-related heart and lung diseases, however, their exact mechanism is not clear.

Dilated cardiomyopathy update: infectious-immune theory revisited

Dilated cardiomyopathy is characterized by dilatation of the left or right ventricle, or both ventricles. The degree of myocardial dysfunction is not attributable to abnormal loading conditions. The infectious-immune theory has long been hypothesized to explain the pathogenesis of many etiologically unrecognized dilated cardiomyopathies. Inflammations followed by immune reactions, which may be excessive, in the myocardium, evoked by external triggers such as viral infections and/or autoimmune antibodies, continue insidiously, and lead to the process of cardiac remodeling with ventricular dilatation and systolic dysfunction. This ultimately results in dilated cardiomyopathy. Hepatitis C virus-associated heart diseases are good examples of cardiac lesions definitely induced by viral infections in humans that progress to a chronic stage through complicated immune mechanisms. Therapeutic strategies for myocarditis and dilated cardiomyopathy have been obtained through analyses of the acute, subacute, and chronic phases of experimental viral myocarditis in mice. The appropriate modulation of excessive immune reactions during myocarditis, rather than their complete elimination, appears to be a key option in the prevention and treatment of dilated cardiomyopathy. The clinical application of an NF-κB decoy and immune adsorption of IgG3 cardiac autoantibodies have been used as immunomodulating therapies and may provide novel approaches for the treatment of refractory patients with dilated cardiomyopathy. Conventional therapeutic agents for chronic heart failure such as β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists in particular should be re-evaluated on the basis of their anti-inflammatory properties in the treatment of dilated cardiomyopathy.

Lessons learned from experimental myocarditis

We have developed murine models of viral myocarditis induced by encephalomyocarditis (EMC) virus in which severe myocarditis, congestive heart failure and dilated cardiomyopathy occur in high incidence. From these models, we have learned the natural history and pathogenesis and assessed not only new diagnostic methods but also therapeutic and preventive interventions. Autoantibodies against cardiac troponin I appeared in spontaneously developing autoimmune myocarditis in PD-1 deficient mice, who lack the T-cell receptor costimulatory molecule PD-1. The passive transfer of this antibody induced myocardial dysfunction. Later, this autoantibody was found in patients with myocarditis. Mast cell deficiency had beneficial effects in the viral myocarditis model, and anti-allergic agents prevented viral myocarditis. Angiotensin-converting enzyme inhibitors, angiotensin II receptor blocker and an aldosterone receptor antagonist improved viral myocarditis, suggesting that the renin-angiotension-aldosterone system may play an important role in the pathogenesis of viral myocarditis. Differential modulation of cytokine production was seen with various calcium channel blockers, and some calcium channel blocker improved viral myocarditis. Viral infection could lead to increased synthesis of immunoglobulin light chains (FLC). Serum levels of FLC were increased in myocarditis, and exogenously given FLC inhibited viral replication and improved myocarditis. We suggest that a strategy of drug development specifically addressing inflammation in myocarditis may provide increased benefit in terms of target organ damage.

Fulminant myocarditis associated with pandemic H1N1 influenza A virus

Fulminant myocarditis associated with influenza A virus is exceedingly rare, with only a few cases reported in the literature. We describe a previously healthy 10-year-old boy, with a three-day history of flu-like symptoms without antiviral treatment. He was hospitalized with dehydration and hypothermia in the context of persistent vomiting, when he suddenly developed heart failure secondary to fulminant myocarditis. Despite aggressive management, including circulatory support and cardiopulmonary resuscitation measures, the patient died of cardiogenic shock. The postmortem histopathology was compatible with a multisystem viral infection with myocarditis and pulmonary involvement, and H1N1v polymerase chain reaction was positive. The prevalence of influenza-associated fulminant myocarditis remains unknown. Findings reported in the literature raise the possibility that the novel H1N1 influenza A virus is more commonly associated with a severe form of myocarditis than previously encountered influenza strains.

A national survey on myocarditis associated with the 2009 influenza A (H1N1) pandemic in Japan

BACKGROUND

An influenza pandemic occurred in 2009 and myocarditis associated with the 2009 influenza A (H1N1) pandemic was reported among hospitalized patients from August 2009.

METHODS AND RESULTS

The Japanese Circulation Society organized the Clinical Research Committee on Myocarditis Associated with Influenza Pandemic A (H1N1) 2009 and called for a case report on myocarditis for a national survey. The diagnosis of myocarditis was performed using the Guidelines for the Diagnosis and Treatment of Myocarditis (JCS 2009). Fifteen patients were reported to the committee. Fulminant myocarditis developed in 10 patients. Mechanical circulatory support (intra-aortic balloon pumping (IABP) and/or percutaneous cardiopulmonary support (PCPS)) was used on all 10 patients, 8 of whom were rescued. Abnormalities on echocardiography and elevated cardiac enzymes were seen in most of the patients. Myocarditis was found by endomyocardial biopsy in 6 patients. Three patients had complications with pneumonia.

CONCLUSIONS

In reality, myocarditis associated with pandemic influenza A (H1N1) seemed to be more common in hospitalized patients, compared with previous seasonal influenza virus outbreaks. To avoid misdiagnosis of acute myocarditis associated with influenza pandemic A (H1N1) 2009, it is essential to determine the characteristic symptoms, signs, and laboratory findings of acute myocarditis during influenza pandemics. Mechanical circulatory support (IABP and/or PCPS) was required to rescue patients with fulminant myocarditis.