C05 - Anti-desmosomal Antibody as a Potential Biomarker of Arrhythmia Burden in Boxers with Arrhythmogenic Ventricular Cardiomyopathy

Abstract: Background– Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a common entity in Boxer dogs causing syncope or sudden death. As Holter and echocardiographic abnormalities frequently do not develop until after 5-6 years of age, novel biomarkers for identification of affected individuals are needed. Circulating autoantibodies to cardiac desmosomal protein desmoglein-2 (anti-DSG2) have been identified in the serum of people and Boxers with ARVC.

Hypothesis/Objectives- Anti-DSG2 antibodies will discriminate between affected and healthy Boxer dogs and correlate with disease severity as measured by 24h burden of ventricular premature contractions (VPCs) in affected dogs.

Animals– Client-owned Boxer dogs ≥ 5 years of age were recruited.

Methods– Prospective, cross-sectional study. The normal group was comprised of Boxers with < 100 VPCs on 24h Holter and normal echocardiogram. The affected group was comprised of Boxers with > 300 VPCs on Holter or documented ventricular tachycardia. Cardiac biomarkers (high sensitivity troponin-I and NT-proBNP) were evaluated, and Western blots and direct ELISA were carried out using recombinant DSG2 protein.

Results– Fifty-one dogs were enrolled (healthy = 24; affected = 27). Cardiac troponin-I (Mann-Whitney, p < 0.001) and NT-proBNP (Mann-Whitney, p < 0.001) were significantly higher in affected dogs, but anti-DSG2 antibody did not differ between groups (p = 0.63). A positive correlation between VPCs over 24h and anti-DSG2 was observed (Pearson, p = 0.012, r = 0.4, fig 1).

Conclusion: Anti-DSG2 analysis did not discriminate between normal and affected dogs but may have utility for monitoring arrhythmia burden and possibly progression of ARVC.