The actual effect of periostin, no matter it is protective, detrimental or neutral needs further confirmation. According to our results, we concluded that periostin showed good correlation with cardiac systolic function and short term prognosis in ST elevation acute myocardial infarction patients. Higher serum periostin level was associated with worse left ventricular function and deteriorated short term prognosis. In the present study, we visited patients for six months and this was a relatively short period for myocardial infarction patients. Long term observation for cardiovascular major events and clinical prognosis would be needed in the further study. Our present study enrolled myocardial infarction patients with ST elevation and did not include non-ST elevation myocardial infarction patients or unstable angina patients. As these patients shared the similar pathological process as unstable plaque, the serum periostin level in these patients would better be analyzed in further experiments. Dermatomyositis is an autoimmune inflammatory muscle disorder that symmetrically affects primarily the proximal limb, neck, and pharyngeal muscles and is accompanied by a characteristic rash such as Gottron’s papules and heliotrope eyelids. It is often complicated by interstitial pneumonia and is classified into chronic IP and acute/subacute IP on the basis of clinical course. DM-A/SIP is a disease associated with a poor prognosis that resists treatment with glucocorticosteroids and progresses rapidly in a period of weeks to months to death. Recently, early intervention with a combination of GC and a calcineurin inhibitor such as cyclosporine A and tacrolimus and this combination plus intravenous pulse cyclophosphamide therapy was reported to improve the prognosis of DM-A/SIP. However, there are still many patients who cannot be saved even with these regimens. Early additional immunosuppressant therapy is necessary for such patients, but an accurate prognosis or evaluation of the severity is difficult before the beginning of treatment. Clinical amyopathic DM, autoantibodies such as anti-aminoacyl tRNA synthetase and anti-melanoma differentiation-associated gene 5 antibodies, highresolution computed tomography findings such as ground-glass attenuation and reticular opacity, and a decrease in the diffusing capacity on respiratory function tests have been reported as findings related to the severity and prognosis of DM-IP. Recently, among serum biomarkers, KL-6 and ferritin have been reported to be useful prognostic factors for DM-A/SIP. However, prognostic factors of DM-A/SIP are difficult to analyse because, in addition to these factors, the disease type of IP, time until the beginning of treatment, and therapeutic strategy are also known to affect the outcome. We retrospectively investigated the relations of blood gas analysis results and serum markers such as KL-6 and ferritin before the beginning of treatment with outcome in DM-A/SIP patients who underwent early CSA/GC combination therapy and 2-hour postdose blood concentration monitoring. We also evaluated the relations of prospective prognostic factors with outcome in DM-A/SIP.