Autoimmune Mechanisms in the Arrhythmogenesis in Small Children

Aim: To evaluate the impact of autoimmune mechanisms on arrhythmogenesis in pre-school children.

Materials and Methods: Autoantibodies (AB) to components of cardiomyocytes were detected by the method of indirect immunofluorescence in 84 children with various types of tachyarrhythmias and extrasystoles. Data were compared with general population titers of antimyocardial antibodies in blood serum of virtually healthy individuals (1/20-1/40).

Results: The increases in the titers of anti-fibrillar (p=0.006) and anti-sarcolemma (p=0.030) AB were found in patients with clinically significant arrhythmias associated with tachycardia-induced cardiomyopathy and clinical signs of heart failure (HF). Age-related analysis showed that anti-fibrillar and anti-sarcolemma AB were detected more frequently in children of older age. Quantitative analysis revealed statistically significant increases in the titers of anti-fibrillar (p=0.017) and anti-sarcolemma (p=0.011) AB in arrhythmic children aged 3 to 7 years compared with infants. These data can be explained by the fact that the low levels of AB against components of cardiomyocytes in infants are caused by depletion of maternal IgG responsible for passive immune response during the first months of life. By the age of 5 to 7 years, child’s organism is capable of own IgG synthesis, in particular, in response to arrhythmogenic myocardial damage as the immune system has developed by this age.

Conclusions: Infants with suppressed immune responses to damaging factors suffer from severer arrhythmias associated with clinical manifestation of HF. The analysis of AB against components of cardiomyocytes may contribute to elucidating the involvement of autoimmune mechanisms in the arrhythmogenesis in children of different age groups.