Diagnostic Approach to Cardiac Involvement in Idiopathic Inflammatory Myopathies

Cardiac involvement in idiopathic inflammatory myopathies (IIMs) attracts more attention than it ever did because of its morbidity and impact on worse prognosis, although the accurate information needs further epidemiological studies. Early identification and intervention for the diseased heart may help improve the clinical outcomes of IIMs with cardiac involvement. Cardiac troponin assays, allowing for sensitive detection of minor myocardium injury, may provide a new way for early detection for heart involvement in IIMs. While elevated cardiac troponin I (cTnI) specifically indicates cardiomyocyte injury, the elevation of cardiac troponin T (cTnT) levels may not only derive from damaged heart but also diseased adult skeletal muscles in which cTnT could re-express in patients with IIMs. cTnI is the biomarker of choice for diagnosis of cardiac involvement and may also be a prognostic factor in IIMs. Meanwhile, electrocardiography (ECG), cardiac imaging (e.g., echocardiography, cardiac magnetic resonance) and histopathological techniques (e.g., endomyocardial biopsy) take on different degrees of importance for the diagnosis of cardiac involvement. We propose a diagnostic strategy combining the routine use of cTnI assay with other techniques (routine ECG and echocardiography, cardiac magnetic resonance, and or endomyocardial biopsy in necessity) and clinical investigation for early detection of heart involvement in IIMs. Future researches are required to validate the algorithm for performance.