Multimodality imaging and the emerging role of cardiac magnetic resonance in autoimmune myocarditis

Autoimmune responses and inflammation are involved in the excess cardiovascular risk observed in patients with systemic inflammatory diseases. Autoimmune myocarditis is a presentation of an inflammatory reaction of the heart during the course of autoimmune disorders, with most cases seen in systemic lupus erythematosus. Early diagnosis is of great significance because of the likelihood of progression to severe and potentially fatal complications such as arrhythmias, heart block, and heart failure. The clinical presentation of the disease is silent leading to delayed diagnosis when dilated cardiomyopathy or heart failure has already advanced. Therefore, a major issue is whether the diagnosis of myocarditis will continue to require invasive procedures such as endomyocardial biopsy or can be achieved with non-invasive methods. There is increasing evidence that noninvasive cardiac imaging, including tissue Doppler echocardiography and cardiac magnetic resonance (CMR), is able to detect subclinical cases and aid in the initiation of specific treatment when it is more likely to be effective. CMR in particular, has emerged as an important technique in the evaluation of myocarditis using three types of images: T2-weighted (T2-W), early T1-weighted (EGE) images taken after 1 min, and delayed enhanced images (LGE) taken 15 min after the injection of contrast agent. If 2/3 of the imaging sequences are positive, myocardial inflammation can be predicted or ruled out with a diagnostic accuracy of 78%. As our understanding of disease mechanisms improves, multimodality imaging may aid in the development of new diagnostic and therapeutic strategies for this potentially devastating complication of systemic inflammation, but further studies are needed to formally evaluate this.