Abstract 3153: High Frequency of Circulating Organ-specific Anti-Heart Autoantibodies in Arrhythmogenic Right Ventricular Cardiomyopathy: Evidence of Immune-mediated Pathogenesis
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by progressive fibro-fatty replacement of the right ventricular myocardium. Myocarditis has been reported in up to 75% of ARVC cases, but the pathogenic significance of inflammation remains elusive. Serum anti-heart autoantibodies detected by indirect immunofluorescence are organ and disease-specific markers of immune-mediated pathogenesis in a subset of patients with dilated cardiomyopathy and in biopsy-proven myocarditis. Methods. We assessed the frequency of anti-heart autoantibodies in 20 ARVC patients, 12 male, aged 41 ± 14 years. All ARVC patients met the 1994 ESC/ISFC Task force diagnostic criteria. Anti-heart autoantibodies were detected by indirect immunofluorescence on cryostat sections of normal O blood group human myocardium and skeletal muscle. Anti-heart autoantibodies of the organ-specific type reacted with myocardium, but were unreactive with skeletal muscle. Control groups for anti-heart autoantibodies included sera from patients with non-inflammatory cardiac disease (n=160, 80 male, aged 37 ± 17, of whom 55 with established valvular heart disease, 67 with hypertrophic cardiomyopathy, 38 with congenital heart defects), with ischemic heart failure (n=141, 131 male, aged 51 ± 12, all with angiographically documented coronary artery disease and depressed global left ventricular ejection fraction, none with acute myocardial infarction in the last 6 months) and normal blood donors (n=270, 123 male, aged 35 ± 11). Frequencies of autoantibodies in ARVC vs controls were compared by ANOVA. Results. Anti-heart autoanti-bodies were found in 8 (40%) ARVC patients and were in all cases of the organ-specific type. The frequency of organ-specific anti-heart autoantibodies was higher (40%) in ARVC than in non-inflammatory cardiac disease (1%), ischemic heart failure (1%) or normal subjects (2.5%)(p=0.0001). Conclusion. The finding of organ-specific anti-heart autoantibodies supports the involvement of autoimmunity in 40% of patients with ARVC.