Comparison of local electrogram predictors for successful catheter ablation of left-versus right-sided accessory atrioventricular pathways by radiofrequency current

Analysis of local electrogram manifestations is critical to the success of radiofrequency catheter ablation of accessory atrioventricular (AV) pathways. However, despite similar criteria, the ablation of right-sided targets has been less effective than that of left-sided ones. In order to elucidate the possible variations, we systematically analyzed the morphological and timing characteristics of 215 bipolar local electrograms from ablation sites of 65 left-sided accessory AV pathways, and 356 from those of 37 right-sided ones in 92 consecutive patients. By multivariate analysis, we selected the presence of a possible accessory pathway potential, local ventricular activation preceding QRS complex for 20 ms or more (ventricular insertion mapping); and the local retrograde ventriculoatrial continuity, local retrograde ventriculo-atrial interval ≤50 ms (atrial insertion mapping) as the common independent outcome predictors by local electrogram criteria for ablation of left- and right-sided accessory AV pathways. Electrogram stability for left-sided targets and retrograde accessory pathway potential for right-sided ones were additional indicators during atrial insertion ablation. Combination of all local electrogram predictors could have moderate chance of success for ablation of left-sided accessory AV pathways: positive predictive value of 80% and 51% by ventricular and atrial insertion mapping. However, such combination had either low positive predictive value or very low sensitivity in cases of right-sided accessory AV pathways. In conclusion, successful catheter ablation of right-sided accessory AV pathways, as comparing to left-sided ones, necessitated still more breakthrough in addition to local signal analysis.