Objective    To investigate whether radiofrequency (RF) ablation has same efficiency on treatment of atypical atrioventricular nodal reentrant tachycardia (AVNRT) as on that of typical AVNRT.     Methods    According to electrophysiological examination results

21 cases of atypical AVNRT (including 14 cases of slow/slow type and 7 cases of fast/slow type) were found among 248 identified AVNRT who underwent RF ablation from June 2006 to June 2009 in our department

and another 21 age- and gender-matched cases of typical AVNRT from this cohort served as control. The junctional rhythm appeared when slow pathway ablation was performed and successful RF ablation was achieved when the supraventricular tachycardia was no longer inducible. The rate of ventriculoatrial (VA) block of junctional rhythm during slow pathway ablation

numbers of ablation application

procedure time

X-ray exposure

complications

acute success rate and recurrent rate were compared between atypical and typical AVNRT.     Results    There was no obvious difference in the tachycardia cycle length between the 2 groups (P0.05). The H-A interval during tachycardia in patients with atypical AVNRT was longer than that in control group (155.90±40.86 vs 32.62±18.25 ms

P=0.001)

but the A-H interval was shorter in the former than in the later (142.76±78.46 vs 265.29±43.67 ms

P=0.034). All cases were successfully slow pathway ablated. There was no significance between the 2 groups in numbers of ablation application

procedure time

X-ray exposure

complications

and acute success rate. Compared to the control

the rate of VA block of junctional rhythm during slow passway ablation was higher (66.7% vs 9.5%

P=0.02)

but was not associated with the atrioventricular (AV) block. During the follow-up period of 25.3±11.6 months

the rate of recurrence in atypical AVNRT group was higher than that in control group (23.81% vs 4.76%

P0.05).     Conclusion    Slow pathway ablation is effective and safe for atypical AVNRT as for typical AVNRT. Compared to typical AVNRT ablation

the rate of VA block of junctional rhythm during slow passway ablation is higher in atypical AVNRT

but has no relation to the AV block complication. The rate of recurrence after ablation might be a little higher.