Background: Even after successful slow pathway (SP) ablation for atrioventricular-nodal reentrant tachycardia (AVNRT), there may be clinical recurrence in certain patients and it is clinically important to be able to predict that.
Methods and results: In 97 patients with common type AVNRT, the effective refractory period (ERP) of the fast pathway (FP), SP-ERP, and prolongation of the atrio-His (AH) interval (AH) at the time of jump-up phenomenon were investigated. In patients with residual SP, parameters were re-evaluated in a similar manner. SP was successfully ablated and AVNRT was not inducible in all the patients, but residual SP was observed in 54 of the 97 patients, and there was late clinical recurrence in 10 patients (10/54 patients with residual SP and 0/43 without residual SP, p=0.002). The changes in FP-ERP before and after ablation (DeltaFP-ERP) did not differ between recurrent and non-recurrent patients. Among the patients with residual SP, DeltaSP-ERP did not differ between the groups. However, the changes in DeltaAH before and after ablation (DeltaDeltaAH) were larger in non-recurrent (24+/-30 ms) than in the recurrent patients (4+/-7 ms, p=0.042).
Conclusions: In patients with AVNRT, the residual SP and changes in DeltaAH after successful SP ablation might be useful indices of clinical recurrence.