P380Simultaneous endo-epicardial mapping of the human right atrium: unravelling 3-dimensional excitation

Abstract

Abstract Funding Acknowledgements Prof. Dr. NMS de Groot is supported by funding grants from CVON-AFFIP (914728), NWO-Vidi (91717339), Biosense Webster USA (ICD 783454) and Medical Del Abstract Introduction & Purpose Mapping studies demonstrated that endo-epicardial asynchrony (EEA) and conduction disorders, mainly longitudinal dissociation, play an important role in the pathophysiology of atrial fibrillation (AF). The aim of our study was therefore to investigate the correlation between features of conduction disorders assessed in the endo- and epicardial plane and the degree of EEA. Methods In 80 patients (63 male (79%), age 66 ± 9 years, 31 history of AF (39%)) undergoing cardiac surgery, simultaneous endo-epicardial mapping (256 electrodes, interelectrode distance:2mm) of the inferior, middle and superior right atrium (RA) was performed during SR. Areas of conduction block (CB) were defined as conduction delays of ≥12ms, EEA as activation time differences of opposite electrodes of ≥15ms and transmural CB as CB at similar endo-epicardial sites. Results Amount of CB was highest at the endocardium (endo median:1.9% [0-21.6] vs. epi median:1.1% [0-19.2], all locations p < 0.025) and was more pronounced at the superior RA. Amount of conduction block at both the endo-epicardium combined was higher at the superior RA in patients with hypertension (p = 0.046). Likewise, prevalence of transmural CB and EEA,-up to 84ms-, significantly increased from inferior to superior RA (all p < 0.001). Transmural CB at the inferior RA appeared to be associated with a higher incidence of post-operative AF (p = 0.03). Degree of EEA was also highest at superior RA (superior: 17.5ms [16-21.75] vs mid: 17ms [0-20] and inferior: 0ms [0-17], p < 0.001). Prevalence of CB was correlated with prevalence EEA (r= 0.74-0.87; all locations p < 0.001). In patients with hypertension (p = 0.009), diabetes (p = 0.015) and hypercholesterolemia (p = 0.015), EEA degree was higher at inferior RA. Significantly more CB (p = 0.007) and EEA (p = 0.037) were observed in patients with a history of persistent AF compared to patients without AF history. Conclusions This study provides important insights into the complex 3-dimensional endo-epicardial excitation and arrhythmogenesis. Knowledge of 3-dimensional excitation during SR is essential to understand the substrate underlying AF in order to improve (ablative) AF therapy.