Number of Pacing Stimuli for Attaining a Plateau Post-Pacing Interval for Diagnosing Re-Entrant Atrial Tachycardia

Reaching a plateau post-pacing interval (PPI) while increasing the number of pacing stimuli (N_pace) of overdrive pacing is an indicator of establishing entrainment pacing.

This study aimed to investigate whether the N_pace for attaining a plateau post-pacing interval (NPP) can be used for identifying re-entrant atrial tachycardia (AT) circuit.

We studied 43 ATs in 38 patients. At each pacing site, overdrive pacing with an N_pace of 1, 3, 5, and ≥7 was performed. NPP was defined as the smallest N_pace that caused an incremental increase in the PPI to become smaller than tachycardia cycle length (TCL) minus pacing cycle length. NPP was classified as 3, 5, and >5. The relationship between NPP and PPI under the establishment of entrainment pacing (PPI_entrained) was investigated. When PPI_entrained was unavailable, the relationship between NPP and findings on the activation maps was evaluated.

NPP was acquired at 193 pacing sites. Among 170 pacing sites where PPI_entrained was available, 104 of 110 NPP =3 pacing sites had PPI_entrained - TCL ≤30 milliseconds, whereas all 32 NPP >5 pacing sites had PPI_entrained - TCL >30 milliseconds. Among 23 pacing sites where PPI_entrained was unavailable, 7 of 8 NPP =3 pacing sites were on the circuit, whereas all 11 NPP >5 pacing sites were out of the circuit on the activation maps.

NPP obtained using a single mapping catheter may help identify a re-entrant AT circuit without directly confirming the establishment of entrainment pacing.