RANDOMIZED COMPARISON OF ANATOMIC AND ELECTROGRAM MAPPING APPROACHES TO ABLATION OF THE SLOW PATHWAY OF ATRIOVENTRICULAR NODE REENTRANT TACHYCARDIA

Objectives. The purpose of this study was to prospectively compare in random fashion an anatomic and an electrogram mapping approach for abl ation of the slow pathway of atrioventricular (AV) node reentrant tach ycardia. Background. Ablation of the slow pathway in patients with AV node reentrant tachycardia can be performed by using either an anatomi c or an electrogram mapping approach to identify target sites for abla tion. These two approaches have never been compared prospectively. Met hods. Fifty consecutive patients with typical AV node reentrant tachyc ardia were randomly assigned to undergo either an anatomic or an elect rogram mapping approach for ablation of the slow AV node pathway. In 2 5 patients randomly assigned to the anatomic approach, sequential radi ofrequency energy applications were delivered along the tricuspid annu lus from the level of the coronary sinus ostium to the His bundle posi tion. In 25 patients assigned to the electrogram mapping approach, tar get sites along the posteromedial tricuspid annulus near the coronary sinus ostium were sought where there was a multicomponent atrial elect rogram or evidence of a possible slow pathway potential. If the initia l approach was ineffective after 12 radiofrequency energy applications , the alternative approach was then used. Results. The anatomic approa ch was effective in 21 (84%) of 25 patients, and the electrogram mappi ng approach was effective in all 25 patients (100%) randomly assigned to this technique (p = 0.1). The four patients with an ineffective ana tomic approach had a successful outcome with the electrogram mapping a pproach. On the basis of intention to treat analysis, there were no si gnificant differences between the electrogram mapping approach and the anatomic approach with respect to the time required for ablation (28 +/- 21 and 31 +/- 31 min, respectively, mean +/- SD, p = 0.7) duration of fluoroscopic exposure (27 +/- 20 and 27 +/- 18 min, respectively, p = 0.9) or mean number of radiofrequency applications delivered (6.3 +/- 3.9 vs. 7.2 +/- 8.0, p = 0.6). With both the anatomic and electrog ram mapping approaches, the atrial electrogram duration and number of peaks in the atrial electrogram were significantly greater at successf ul target sites than at unsuccessful target sites. Conclusions. The an atomic and electrogram mapping approaches for ablation of the slow AV nodal pathway are comparable in efficacy and duration. If the anatomic approach is initially attempted and fails, the electrogram mapping ap proach may be successful at sites outside the areas targeted in the an atomic approach. With both the anatomic and electrogram mapping approa ches, there are significant differences in the atrial electrogram conf iguration between successful and unsuccessful target sites.