Imaging of Inflammation in Unexplained Cardiomyopathy

Myocarditis is a recognized but underdiagnosed cause of cardiomyopathy due to its wide clinical spectrum and nonspecific presentation. Accurate diagnosis is important because 25% of patients with acute myocarditis develop cardiomyopathy, and of those, approximately 5% per year require heart transplantation or die. Current guidelines for the recognition and treatment of the inflammatory cardiomyopathies are limited. The gold standard for diagnosis, endomyocardial biopsy, has low sensitivity, and thus, multimodality imaging of inflammation plays a crucial role in defining the cardiac abnormalities and in assisting with diagnosis and management. The literature on inflammatory cardiomyopathies is limited to small studies of selected populations due to the diverse etiologies and inherent difficulties in definitive diagnosis. This review focuses on the current and projected use of various imaging modalities, including echocardiography, cardiac magnetic resonance, and nuclear imaging to better define inflammatory cardiomyopathies and aid in their management; it specifically focuses on cardiac sarcoidosis, and giant cell, eosinophilic, and lymphocytic myocarditis.