Idiopathic inflammatory myopathies (IIMs) are a group of autoimmune diseases that includes the main subtypes dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and inclusion body myositis. IIMs are characterized by the involvement of skeletal muscle and multiple organs, including the heart. This review summarizes the pathology, prevalence, biomarkers, imaging and treatment of cardiac involvement in patients with IIMs. The cardiac involvement in these patients is usually subclinical and rarely considered as the main clinical feature at the time of initial consultation, with a prevalence ranging from 4% to 26%. However, it results in a worse prognosis and represents the main cause of mortality in patients with IIMs. The selection of specific serum cardiac biomarkers is essential for the early detection of cardiac involvement in patients with IIMs, such as cardiac troponin I (cTnI), which is preferred over cardiac troponin T (cTnT), followed by diagnostic evaluations including electrocardiography (ECG), echocardiography (ECHO), and cardiac magnetic resonance imaging (CMR). The combination of glucocorticoids, immunosuppressants, and conventional cardiac medications is effective for the management of IIM patients with confirmed cardiac involvement.