Early detection of myocardial involvement in idiopathic inflammatory myopathies detected by cardiac magnetic resonance imaging

Abstract

Background: Idiopathic inflammatory myopathies are heterogeneous autoimmune systemic diseases characterized by chronic progressive muscle weakness and inflammatory infiltrates in skeletal muscle. The frequency of cardiac involvement varies between 9% and 72%, mainly dependent on patient selection, definition and diagnostic tools applied. Heart failure is the most frequent finding. Cardiac magnetic resonance imaging (CMR) has been shown to provide reliable and valuable information about cardiac function and inflammatory process in one examination. Hypothesis: Aim of our prospective study was to characterize cardiac involvement using a comprehensive CMR protocol. Methods: Fifty-three consecutive patients with histologically proven idiopathic inflammatory myopathy were enrolled into the study. Blood levels of Creatine kinase (CK) and myocardial CK (CK-MB) were analyzed from each patient. All patients underwent CMR examination in a 1.5-T whole body scanner. 3D short-axis functional steady-state free precession and late gadolinium enhancement (LGE) sequences were acquired in all patients covering the entire left and right ventricle. CMR images were analyzed by two experienced and blinded readers in consensus. Besides functional analysis LGE images were analyzed for hyperenhancement and quantified as LGE percentage of myocardial mass. Results: Reduced left ventricular function (ejection fraction < 60%) was present in 9 (17%) patients. These patients exhibited significantly higher blood levels of CK-MB (283±193 vs. 175±221 U/l, p=0.02) than patients with preserved LVEF. Early myocardial enhancement (>45% signal intensity increase) was more often present (6 out of 9 [66.7%] vs. 25 out of 44 [56.8%], p=.014) as well as LGE patterns consistent with myocardial inflammation (9 out of 9 [100%] vs. 24 out of 44 [54.5%], p=.001). LGE was most often observed in the inferior and lateral segments. Conclusion: The results of this study show that CMR is able to detect cardiac involvement in idiopathic inflammatory myopathies. Early diagnosis using CMR could result in early therapy of heart failure, leading to beneficial ventricular remodeling and thus improving living quality and survival in these patients.