Background: Several lines of evidence support the involvement of autoimmunity in Myocarditis and Dilated Cardiomyopathy (DC). Serum anti-heart autoantibodies (AHA) are organ and disease-specific autoimmune markers in Myocarditis and Dilated Cardiomyopathy. Biopsy-proven myocarditis is frequently reported in Arrhythmogenic Cardiomyopathy (AC) but its etiopathogenetic significance remains poorly understood.
Purpose: The aim of the study was to assess the frequency of AHA in AC patients and their relationship with a worst clinical phenotype.
Methods: We assessed serum AHA in 57 AC patients (52,6%male, mean age 32±12years) met the 2010 revised ESC Task force diagnostic criteria. AHA was detected by indirect immunofluorescence on cryostat sections of normal O blood group human myocardium and skeletal muscle, blindly from clinical and genetic diagnosis. All patients underwent clinical and non-invasive assessment including a 12 lead electrocardiogram, echocardiography, 24-hour Holter Ecg, exercise testing, late potentials ECG and cardiac MRI. At follow up all patients performed 12 lead electrocardiogram, echocardiography, 24-hour Holter Ecg and exercise testing.
Results: In 31 AC patients (54%) was detected the presence of AHA. At diagnosis AHA positive patients presented more often a familiar history of autoimmune disease (38,5% vs 11,4% p-value:0,05); they had more supraventricular extra beats (281,69±702,6 vs 24,45±45, p-value=0,05) and premature ventricular contraction polymorphism at Holter ecg (48,4% vs 15,4%, p-value=0,001). Furthermore, at initial echocardiography evaluation, the presence of AHA antibodies was associated with a greater dimension of right ventricular outflow tract (RVOT) RVOTP:mm/m2 17,39±2,72 vs 15,29±2,68 p-value=0,005; RVOT1: 23,775±3,4 vs 16,19±2,25 p-value=0,001; RVOT2:14,72±2,36 vs 13,15±1,71 p-value=0,006). At follow up visit (mean 6 years±2,7) AHA patients showed more syncopal episodes (10pt vs 2pt, p-value=0,04) more non sustained ventricular tachycardia at Holter ecg (14pt vs 1pt, p-value=0,0006) and more patients were in atrial fibrillation (5pt vs 1pt, p-value 0,06).
Conclusion: For the first time we demonstrated that the presence of AHA in patients with AC is associated with a more severe disease phenotype, indeed it were significantly correlated with the size of the RVOT, with the complexity of arrhythmias and with the presence of syncope and ventricular tachycardia at follow-up.