P5556Impact of viral genome detection in endo-myocardial biopsy of arrhythmogenic cardiomyopathy substrate

Abstract Background Arrhythmogenic cardiomyopathy (ACM) is a genetically inherited cardiomyopathy characterized by myocardial fibro-fatty replacement. A pathogenetic role of viral myocardial infections in ACM natural history has been proposed over the years, although no definitive conclusion has been reached yet. Purpose To describe viral genome presence into a cohort of ACM biopsy proven patients (pts) and its impact on clinical features and outcome. Methods A cohort of all ACM pts undergoing an invasive third level evaluation at our institution was enrolled. All pts underwent a cardiac magnetic resonance (MR), an invasive electrophysiological study (EPS) with endo-cavitary electro-anatomical mapping (EAM), and a EAM guided endo-myocardial biopsy (EMB). Viral genome research through molecular biology techniques was performed on all biopsied samples. According to arrhythmic risk evaluation, a trans-catheter ablation (TCA) and/or an internal cardioverter device (ICD) implant was performed. Clinical arrhythmic presentation, MR data, arrhythmia inducibility at EPS, EAM and EMB characteristic, and arrhythmic events at a 12-month follow up visit were retrieved in all pts and compared between the viral genome positive (v+ACM) and negative group (v-ACM). Results Forty-five pts were enrolled in our study (48±13 years; 66% male); the EMB samples of 7 (15%) pts presented a lymphocytic infiltrate and tested positive for viral genome (n=3 B19 Parvovirus; n=2 for Citomegalovirus; n=2 for Ebstein-Bar Virus) [Figure1]. At arrhythmic presentation, complex ventricular arrhythmias (NSVT, SVT and FV) were more frequent in the v+ACM group (86% vs 50%; p=0.039). Both left and right ventricular ejection fraction at MR resulted more depressed in the v+ACM group (44±7 vs 52±2 and 47±2 vs 52±2; p=0.047 and p=0.041). Complex ventricular arrhythmia inducibility at EPS was more frequent in v+ACM (72% vs 34%; p=0.032), while no differences in pathological potentials rate and extension at unipolar and bipolar EAM were found. TCA was performed in 55% and 57% and an ICD was implanted in 29% and 42% in the v+ACM and v-ACM group respectively. No differences in 12-months arrhythmic event rates (39% vs 42%) between the two groups were described. EBM at different magnifications/stains Conclusion In our cohort a viral infection super-imposed to the fibrofatty infiltration was found in 15% of the patients. ACM pts testing positive for viral genome at the EMB had a more severe arrhythmic disease presentation, a more impaired heart function, and a higher rate of complex ventricular arrhythmias at disease presentation, but seemed to respond as well as viral genome negative ACM to ablative and pharmacological treatment