CATHETER-BASED 3-DIMENSIONAL ELECTROGRAM ACQUISITION AND ANALYSIS SYSTEM

Conventional time-domain electrogram (EGM) characteristics have a poor positive predictive value for successful accessory pathway (AP) ablat ion location. The authors hypothesized that a computer-generated three -dimensional electrogram (3D-EGM) of myocardial activation along the a trial aspect of the tricuspid or mitral annulus created from sequentia lly obtained, signal-averaged endocardial bipolar EGMs and time aligne d to a known myocardial reference could improve AP localization and ab lation. Serial signal-averaged EGMs, digitized at 4 KHz and filtered f rom 1 to 2,500 Hz, were sampled at known locations along the atriovent ricular ring. Up to 15 EGMs were time aligned to a known myocardial ac tivation reference and displayed as a 3D-EGM. Time-domain 3D-EGMs were then analyzed for morphologic characteristics corresponding to effect ive radiofrequency ablation location in 33 patients with left-sided AP s, 5 with posteroseptal APs, and 5 with right free wall APs. A charact eristic retrograde atrial 3D-EGM polarity reversal identified AP inser tion sites in all free wall locations with a 97% sensitivity, 46% spec ificity, and 72% positive predictive value. Posteroseptal APs were cha racterized by left posterior paraseptal atrial 3D-EGM polarity reversa l, but proximal coronary sinus activation preceded endocardial activat ion in all. Three-dimensional electrogram polarity reversal of the ret rograde atrial activation vector has a high sensitivity and positive p redictive value for effective ablation location patients with left and right free wall APs, but should be used with caution in patients with posteroseptal APs.