Imaging cardiac sarcoidosis and infiltrative diseases: diagnosis and therapeutic response

Infiltrative heart disease is an encompassing term referring to different pathological entities that involve infiltration of the myocardium by either abnormal substances or inflammatory cells. These infiltrates can impair cellular function, induce necrosis and fibrosis, or otherwise disrupt myocardial architecture resulting in a wide spectrum of structural and functional impairment. Depending on the specific disorder and stage of disease, patients may present with minimal cardiac abnormalities, or may have findings of advanced restrictive and/or dilated cardiomyopathy. Furthermore, patients may often be misdiagnosed with more common conditions such as hypertensive, hypertrophic or ischemic cardiomyopathies. Correlation of cardiac findings with clinical, serologic or pathologic data is critical in many of these conditions. While cardiac involvement may be detected by echocardiography, other imaging modalities such as cardiac magnetic resonance, single-photon emission computed tomography, or positron emission tomography provide additional critical diagnostic, prognostic and therapeutic information. Advanced imaging modalities also provide quantitative data that can further risk stratify patients, monitor disease progression, and guide management. In this review we provide an overview of infiltrative heart disease from an imaging perspective, with a particular focus on cardiac sarcoidosis and cardiac amyloidosis.