CARDIAC AUTOANTIBODIES IN DILATED CARDIOMYOPATHY BECOME UNDETECTABLE WITH DISEASE PROGRESSION

Objective-To determine the relation of cardiac autoantibody and diseas e status in a consecutive series of patients with dilated cardiomyopat hy by prospective antibody testing art diagnosis and at follow up. Met hods-Antibody status was assessed by indirect immunofluorescence in 11 0 patients with dilated cardiomyopathy (85 male, mean (SD) age 44 (13) years) at diagnosis and see follow up (mean (SD) 14 (12) months); in 57 of them cardiac specific anti-a myosin antibody titres were also me asured by an enzyme-linked immunosorbent assay (ELISA). Patients under went complete evaluation at diagnosis and clinical and non-invasive as sessment at fellow up, including exercise testing with maximal oxygen consumption measurements. Results-The frequency of cardiac specific an tibodies by immunofluorescence was lower at follow up than at diagnosi s (28 (25%) v 11 (10%), P = 0.002). Mean (SEM) anti-alpha myosin antib ody titres at follow up were also lower than at diagnosis (0.24 (0.02) v 0.30 (0.02), P = 0.038); 24% of patients at diagnosis and 14% at fo llow up had an abnormal ELISA result. None off the patients who were n egative by immunofluorescence or ELISA at diagnosis became positive at follow up. Presence of antibody at diagnosis was associated with mild er symptoms and greater exercise capacity at follow up and persistence of antibody at follow up was associated with stable disease and milde r symptoms at diagnosis. Conclusions-Cardiac specific autoantibodies i n dilated cardiomyopathy become undetectable with disease progression; this is a recognised feature of other autoimmune conditions, such as type 1 diabetes. Detection of these antibodies at diagnosis and at fol low up may provide a non-invasive marker of early dilated cardiomyopat hy.