Abstract 18547: Beat-to-Beat Variations in Activation Recovery Interval Derived From the Right Ventricular Electrogram Can Monitor Arrhythmic Risk Under Anesthetic and Awake Conditions in the Chronic Atrioventriclar Block Dog

Introduction: In the chronic atrioventricular block (CAVB) dog model, beat-to-beat variation in repolarization in the left ventricle (LV) quantified as short-term variability of the left monophasic action potential duration (STV LVMAPD ) abruptly increases before the first short coupled ectopic beat (EB), specifically in subjects that demonstrate subsequent multiple EBs and repetitive Torsades de Pointes (TdP) arrhythmias. Applicability of STV to monitor arrhythmic risk 24/7 in clinical practice would be feasible through the use of the intracardiac electrogram (EGM) derived from a right ventricle (RV) lead from a pacemaker or implantable cardioverter defibrillator (ICD). Therefore, we performed 1) a retrospective analysis to show that STV RVMAPD is comparable to the STV LVMAPD 2) a prospective analysis to investigate the value of the STV of the activation recovery interval (ARI) derived from the RV EGM (STV RVARI ) to monitor arrhythmic risk in anesthetic (2a) and awake (2b) conditions. Methods: 1) STV LVMAPD and STV RVMAPD were measured in 30 anaesthetized CAVB dogs inducible (≥3TdP) after a challenge with dofetilide. 2a) Under anesthesia 10 inducible CAVB dogs implanted with an ICD with EGM recording capabilities, were challenged with dofetilide to compare STV RVMAP and STV RVARI . 2b) In 8 CAVB dogs oral cisapride (10-20 mg/kg) was administered to provoke arrhythmias in awake conditions. Results: 1) Both STV LVMAPD and STV RVMAPD significantly increased before occurrence of the first EB (1.29±0.58 to 3.05±1.70ms and 1.11±0.53 to 2.18±1.43ms respectively (p=0.001). Spearmans rho 0.62 (p RVARI increased from 2.82±0.33 to 3.77±0.69ms (p=0.001). Spearmans rho between STV RVMAPD and STV RVARI was 0.42 (p RVA RI was observed in the first hour after cisapride from 2.65±0.55 to 3.56±0.30ms (p=0.03). Conclusion: Behavior of STV derived from the RV is comparable to the LV. STV RVARI increases significantly before the occurrence of an arrhythmia in awake and anaesthetized conditions. This can be integrated in devices to 24/7 monitor arrhythmic (in)stability and initiate and or modify antiarrhythmic therapies.