ObjectiveTo analyze the incidence of heart disease, its clinical manifestations and risk factors in patients with polymyositis (PM) and dermatomyositis (DM). MethodWe collected the clinical data of 138 PM (n=78) and DM (n=60) patients treated between January 2008 and March 2014, among whom there were 64 males and 74 females with an average age of (48.5±19.6) years old, and an average disease course of (84.5±6.9) months. We analyzed their incidence of heart disease, its clinical manifestations and the risk factors. Subsequently, we adopted single-factor analysis to analyze such factors as age, gender, disease course, kinds of disease, creatine kinase (CK), CK-MB, CK-MB/CK, troponin T, antinuclear antibodies, anti-SSA antibody, erythrocyte sedimentation rate, C-reactive protein, disease activity score, muscle force, pulmonary interstitial lesions and pulmonary artery hypertension. ResultsThere were 59 (42.7%) patients with heart disease, 48 (34.8%) with abnormal electrocardiogram, and 52 (37.7%) with abnormal color Doppler ultrasound results. Logistics multiple factors regression analysis found that the course of the disease (OR=1.669, P=0.010), myositis disease activity score (OR=7.456, P<0.001), pulmonary interstitial lesions (OR=4.568, P=0.014) were risk factor for heart disease in PM/DM patients. ConclusionsLong disease course duration, high myositis activity score and pulmonary interstitial lesions are strong predictors for heart damage in PM/DM patients.