RADIOFREQUENCY MODIFICATION OF THE ATRIOVENTRICULAR NODE IN PATIENTS WITH CHRONIC ATRIAL-FIBRILLATION - COMPARISON BETWEEN ANTERIOR AND POSTERIOR APPROACHES

Introduction: We compared, in a prospective and randomized fashion wit h a cross-over design, the anterior and posterior approaches to radiof requency (RF) modification of the AV node in patients with chronic atr ial fibrillation, Methods and Results: Thirty-three patients were rand omized to receive first an anterior (group I) or posterior (group II) approach for RF modification of AV nodal conduction. Patients who did not fill the endpoint ventricular rate (< 90 beats/min) were crossed o ver to the alternative approach, After the anterior approach in group I patients, mean ventricular rate was significantly lower than in grou p II patients after the posterior approach (79.6 +/- 18.8 beats/min vs 110.8 +/- 16.2 beats/min, P < 0,001), In group I, 14 (82 %) of 17 pat ients fulfilled the endpoint, 1 (6%) had complete AV block, and 2 (12% ) were crossed over to the posterior approach fulfilling the endpoint, In group II, ii (25%) of 16 patients fulfilled the endpoint, No trans ient or permanent high-degree AV block was observed. Among the 12 pati ents who were crossed over to the anterior approach, 8 fulfilled the e ndpoint, whereas 3 had permanent high-degree AV block, RF ablation car ried out only in the anterior region was safer than a stepwise approac h (6% vs 33% incidence of AV block), even though the difference did no t reach statistical significance (P = 0,09), Conclusion: Posterior AV nodal modification is less effective but safer than anterior AV nodal modification. However, to reduce the incidence of AV block, the anteri or approach is preferable to a stepwise approach from the posterior to the anterior zone.