Inflammatory Cardiomyopathic Syndromes
Inflammatory activation occurs in nearly all forms of myocardial injury. In contrast, inflammatory cardiomyopathies refer to a diverse group of disorders in which inflammation of the heart (or myocarditis) is the proximate cause of myocardial dysfunction, causing injury that can range from a fully recoverable syndrome to one that leads to chronic remodeling and dilated cardiomyopathy. The most common cause of inflammatory cardiomyopathies in developed countries is lymphocytic myocarditis most commonly caused by a viral pathogenesis. In Latin America, cardiomyopathy caused by Chagas disease is endemic. The true incidence of myocarditis is unknown to the limited utilization and the poor sensitivity of endomyocardial biopsies (especially for patchy diseases such as lymphocytic myocarditis and sarcoidosis) using the gold-standard Dallas criteria. Emerging immunohistochemistry criteria and molecular diagnostic techniques are being developed that will improve diagnostic yield, provide additional clues into the pathophysiology, and offer an application of precision medicine to these important syndromes. Immunosuppression is recommended for patients with cardiac sarcoidosis, giant cell myocarditis, and myocarditis associated with connective tissue disorders and may be beneficial in chronic viral myocarditis once virus is cleared. Further trials of immunosuppression, antiviral, and immunomodulating therapies are needed. Together, with new molecular-based diagnostics and therapies tailored to specific pathogeneses, the outcome of patients with these disorders may improve.