RADIOFREQUENCY CATHETER MODIFICATION OF T HE SLOW PATHWAY TO CURE ATRIOVENTRICULAR NODE REENTRANT TACHYCARDIA

The purpose of this study was to evaluate the long-term follow-up (> 6 months) modification of the slow pathway of atrioventricular node ree ntrant tachycardia (AVNRT). Until August 1995, a total of 151 patients (111 female, 40 male, mean age 50.3 +/- 11.1 years) underwent slow pa thway modification using radiofrequency (RF) current. The mapping cath eter was primarily placed to the midseptum in close proximity to the c oronary sinus ostium and target sites were identified by a multicompon ent atrial electrogram (AEGM). This approach was effective in 149 (98. 6%) patients requiring 3.9 +/- 3.5 RF pulses (median 3, range 1-23). P rocedure duration was 121 +/- 46.7 min (median 120, range 60-300) and fluoroscopy exposure was 16.5 +/- 10.5 min (median 14, range 3-69). 2 patients (1.3%) developed complete AV block requiring permanent pacema ker implantation. During follow-up of 18.4 +/- 6.2 months 12 patients (7.9%) had recurrence of AVNRT. Predictors of a successful site includ ed a longer duration of the AEGM (62.1 +/- 13.8 vs. 45.7 +/- 8.6 ms; p < 0.01), a shorter interval from the offset of AEGM to His bundle act ivity (10.9 +/- 12.5 vs. 21.6 +/- 11.3 ms; p < 0.01), and a greater ex tent of fractionation (3.7 +/- 1.0 vs. 3.0 +/- 1.1 peaks; p < 0.01). R adiofrequency catheter modification of the slow pathway using a combin ed and electrogram mapping approach is effective and safe during long- term follow-up and should be recommended as the therapy of first choic e in symptomatic patients.