1173Anti-heart and anti-intercalated disk autoantibodies: possible novel biomarkers of cardiac sarcoidosis

Abstract Background Sarcoidosis is an immune-mediated disease; cardiac involvement, a granulomatous form of myocarditis, is under-recognised and prognostically relevant, as it can present with significant morbidity and mortality. Anti-heart autoantibodies (AHA) and anti-intercalated disk autoantibodies (AIDA) are reliable autoimmune markers in non-sarcoidosis myocarditis forms. Purpose The aim of this study was to assess the potential role of serum AHA and AIDA in cardiac sarcoidosis. Methods This is a cross-sectional study on a series of 29 patients with biopsy proven extra-cardiac sarcoidosis and with biopsy-proven or clinically suspected cardiac involvement, who were tested for AHA and AIDA. Patients were recruited in two recruiting tertiary centres, in USA and Italy. AHA and AIDA were detected by indirect immunofluorescence on human myocardium and skeletal muscle. Controls included sera from patients with non-inflammatory cardiac disease (NICD) (n=160), with ischemic heart failure (IHF) (n=141) and normal blood donors (NBD) (n=270). Results The frequencies of AHA and of AIDA were higher in sarcoidosis (86%; 62%) than in NICD (8%; 4%), IHF (7%; 2%), NBD (9%; 0%) (p=0.0001; p=0.0001 respectively). Sensitivity and specificity were: 86% and 92% for positive AHA and 62% and 98% for positive AIDA, respectively (see figure). Figure 1 Conclusions The detection of serum AHA and AIDA in biopsy-proven or clinically suspected cardiac sarcoidosis supports the involvement of heart-specific autoimmunity in the majority of our cases and may provide a novel non invasive diagnostic marker.