SELECTIVE RADIOFREQUENCY CATHETER ABLATION OF FAST AND SLOW PATHWAYS IN 100 PATIENTS WITH ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

One hundred patients received selective radiofrequency ablation of retrograde fast pathway (32 patients, group 1) or slow pathway (68 patients, group II) to treat drug-refractory atrioventricular nodal reentrant tachycardia. In group 1, a mean of 6 +/- 3 radiofrequency pulses eliminated the retrograde fast pathway. Thirty patients were free of symptoms and were not receiving antiarrhythmic drugs; two patients had accidental atrioventricular block. One patient had recurrent tachycardia and received a repeated ablation (slow pathway ablation). In group II, a mean of 9 +/- 4 radiofrequency pulses eliminated the slow pathway in 68 patients. All patients were free of symptoms and were not receiving antiarrhythmic drugs. One patient had recurrent tachycardia and received a repeated ablation. Serial follow-up electrophysiologic studies (immediate [20 to 30 minutes], early [5 to 7 days], and late [3 to 6 months]) showed that selective ablation of retrograde fast pathway was associated with nonspecific injury on the antegrade fast pathway (increase of AH interval) without effects on the slow pathway. Selective ablation of slow pathway was associated with nonspecific injury on the retrograde fast pathway in 15 patients (22%), but the antegrade fast pathway conduction parameters did not change significantly. Thus retrograde and antegrade fast pathway may be anatomically similar or have different sensitivities to radiofrequency energy, and slow pathway may be anatomically distinct from fast pathway. We conclude that (1) selective radiofrequency ablation of retrograde fast or slow pathway could cure atrioventricular nodal reentrant tachycardia with a high success rate (98%) and a low recurrence rate (2%) during a follow-up period of 6 to 18 months, but fast pathway ablation was associated with accidental atrioventricular block (5%), and (2) serial follow-up electrophysiologic studies elucidated the possible mechanisms of cure in atrioventricular nodal reentrant tachycardia.