The quest for diagnostic approaches of cardiac involvement in polymyositis and dermatomyositis.

Polymyositis (PM) and dermatomyositis (DM) are autoimmune diseases characterized by inflammation of skeletal muscle, primarily manifesting as chronic muscle weakness. Extramuscular organs can also be affected. Cardiac involvement is one of the visceral organ damages whose prevalence is underestimated and is a marker of poor prognosis leading to irreversible dysfunction or even death. Although early and accurate recognition of cardiac involvement remains a key barrier to improving survival in PM/ DM patients, considerable progress has been made, and an overview will be provided in this review. The new concept of multimodality imaging, which involves an integrated approach of echocardiography (Echo), cardiac magnetic resonance and sometimes positron emission tomography (PET), can facilitate diagnosis. The development of ultrasound technology, including strain analysis, stress Echo and contrast-enhanced Echo, helps disclose early cardiac dysfunction more sensitively than conventional Echo. Cardiac magnetic resonance unveils silent, acute or chronic myocarditis in PM/DM and is used to monitor treatment efficacy due to its excellent tissue characterization. PET can be useful thanks to the appearance of new tracers that can eliminate the effects of glucose uptake by normal cardiomyocytes. The sensitivity of endomyocardial biopsy may be increased by targeted sampling with the guidance of cardiac imaging. Troponin I is specific to cardiac injury, and investigations into antibodies against cardiac tissue are being carried out. Disease-specific mechanisms and therapies are also discussed to give more insights into cardiac involvement in PM and DM.