Myocarditis and Inflammatory Cardiomyopathy

Abstract

Activation of the inflammatory system occurs in most patients with advanced heart failure, regardless of etiology, and contributes to the pathophysiological milieu and the progression of the disease. The term inflammatory cardiomyopathy (ICM) refers to a group of disorders for which an acute or chronic myocardial inflammation is the central cause of abnormal cardiac structure or impaired cardiac function. The most common cause of inflammatory cardiomyopathy is lymphocytic myocarditis, which is most usually triggered by a viral infection, and occasionally by other infectious agents. Rare causes of specific inflammatory cardiomyopathies include cardiac sarcoidosis, giant cell myocarditis and eosinophilic myocarditis. Inflammatory cardiomyopathy can also occur in connection with autoimmune inflammatory diseases. Typical manifestations of inflammatory cardiomyopathy include chest pain, heart failure, and arrhythmias, but these symptoms and signs are unspecific. Although non-invasive diagnostic methods are emerging, the gold standard of diagnosis is the histological examination of an endomyocardial biopsy. Owing to the invasive nature of this technique and a modest diagnostic sensitivity, its use is limited. Therefore, the identification of inflammatory cardiomyopathy is elusive and the true incidence of the condition remains unknown. In most cases of lymphocytic myocarditis, recovery occurs within a few weeks following supportive treatment. In patients with cardiac sarcoidosis, giant cell myocarditis or eosinophilic myocarditis the use of immunosuppressive treatment is recommended, as is the case in myocarditis associated with autoimmune disorders. Such interventions may also have beneficial effects in chronic viral myocarditis once the virus has been cleared. In severe cases, treatment with mechanical circulatory support and/or heart transplantation may be required. Randomized intervention trials including antiviral, immunomodulating, or immunosuppressive agents are lacking. Similarly, new molecular-based methods and therapies tailored to specific pathogeneses have a potential to improve diagnosis and outcomes in patients with inflammatory cardiomyopathy. Still, such techniques and interventions are to be evaluated in adequate randomized controlled studies.