LATE CLINICAL AND ELECTROPHYSIOLOGIC OUTCOME OF RADIOFREQUENCY ABLATION THERAPY BY THE INFERIOR APPROACH IN ATRIOVENTRICULAR NODE REENTRY TACHYCARDIA

A late electrophysiologic study was conducted in 182 of 289 patients w ith slow-fast atrioventricular node reentry tachycardia 81 +/- 36 days after radiofrequency ablation therapy by the inferior approach. Of th ese 182 patients, electrophysiologic study immediately after ablation revealed a selective modification of the slow pathway in 159, a modifi cation of both the slow and fast pathways in 15, a modification of the fast pathway alone in 3, and failure of ablation in 5. One hundred tw o patients had no induction of echoes; 75 had induction of fewer than four echoes; and 5 had induction of sustained tachycardia with or with out isoproterenol infusion. The late electrophysiologic study in these 182 patients revealed a persistent effect without changes in conducti on properties in 161 (88%) patients. A change in conduction properties was noted in 21 patients, including 5 with resumption of slow- or fas t-pathway conduction with induction of sustained tachycardia, 8 with i mproved fast- or slow-pathway conduction, and 8 with an additional dep ression of fast- or slow-pathway conduction. Of the 102 patients with no induction of echoes and the 75 patients with induction of fewer tha n four echoes during the immediate postablation electrophysiologic stu dy, 5 (3 and 2, respectively) patients had induction of tachycardia. O f the 5 patients with induction of sustained tachycardia in the immedi ate postablation electrophysiologic study, 3 continued to have inducti on of sustained tachycardia; 1 had induction of echoes only; and 1 had no induction of echoes. The predictability of late success by using a combination of induction of no and fewer than four echoes in the imme diate postablation electrophysiologic study had a sensitivity of 99%, a specificity of 38%, a positive predictive value of 97%, a negative p redictive value of 60%, and a total predictive accuracy of 96%. Thus t he effects of radiofrequency ablation persist in the majority of patie nts during follow-up, and elimination of all echoes is unnecessary for achieving a late success.