Three‐Dimensional Electrogram Mapping Improves Ablation of Left‐Sided Accessory Pathways

Conventional electrogram mapping techniques for localization of accessory pathways during radiofrequency ablation procedures are time consuming and often inaccurate. We hypothesized that a computer generated, three-dimensional electrogram of retrograde atrial activation created from signal-averaged sequential endocardial bipolar electrograms (collected from the atrial aspect of the mitral annulus using a single transseptal catheter and then time aligned to a known myocardial activation reference) would improve left-sided accessory pathway atrial insertion site identification and increase ablation efficiency. Ablation efficiency was defined by procedure time, fluoroscopy time, duration of radiofrequency energy required to achieve initial accessory pathway block, cumulative ablation energy per procedure, and number of radiofrequency energy applications. Patients with single left-sided accessory atrioventricular connections were studied. Standard mapping results in 31 patients (group A) were compared to a three-dimensional electrogram approach used in 26 patients (group B). Three-dimensional electrogram mapping reduced procedure time (group A 3.8 +/- 1.6 vs group B 2.8 +/- 0.9 hours, P < 0.004), fluoroscopy time (group A 45.3 +/- 35.0 vs group B 25.1 +/- 10.5 min, P < 0.02), time to accessory pathway block (group A 2.6 +/- 1.5 vs group B 1.2 +/- 0.5 sec, P < 0.002), cumulative radiofrequency energy (group A 2126 +/- 2207 vs group B 636 +/- 586 joules, P < 0.0008), and radiofrequency energy applications (group A 5.0 +/- 4.4 vs group B 1.7 +/- 1.2, P < 0.0002). We conclude that three-dimensional electrogram mapping improves left-sided accessory pathway atrial insertion localization, reduces ablation procedure time and radiation exposure, and improves ablation efficiency.