Use of Programmed Ventricular Extrastimulus During Supraventricular Tachycardia to Differentiate Atrioventricular Nodal Re-Entrant Tachycardia From Atrioventricular Re-Entrant Tachycardia.

Objectives: This study hypothesized that early coupled ventricular extrastimuli (V) stimulation might yield a more robust differentiation between atrioventricular nodal re-entrant tachycardia (AVNRT) and atrioventricular re-entrant tachycardia (AVRT).

Background: Programmed V during supraventricular tachycardia are useful to differentiate AVNRT from AVRT by subtracting the ventriculoatrial (VA) interval from the stimulus to atrial depolarization (stimulus atrial [SA]) interval, but all such maneuvers have limitations.

Methods: Patients with either AVNRT or AVRT were investigated. The entire tachycardia cycle length (TCL) was scanned with V delivered from the right ventricular apex. The SA-VA difference was calculated with V clearly resetting the tachycardia. The prematurity of V was calculated by dividing the coupling interval (CI) by the TCL.

Results: A total of 210 patients (102 with AVNRT) were included. The SA-VA difference was >70 ms in all AVNRT patients and was <70 ms in all AVRT patients with right and septal accessory pathways (APs), except for those with decremental APs, in whom there was an overlap between AVNRT and AVRT with left APs. However, a SA-VA difference >110 ms with a CI/TCL of <65% distinguished AVNRT from AVRT using the left AP, with sensitivity and specificity of 87% and 100%, respectively. Ventricular overdrive pacing resulted in tachycardia termination or AV dissociation in 28% of patients compared with 15% of patients using the V technique (p = 0.008).

Conclusions: A SA-VA of >70 ms using the V technique differentiated AVNRT from AVRT using septal and right APs. Use of the V technique with a short CI differentiated AVNRT from AVRT using left APs. The V technique less frequently resulted in tachycardia termination compared with ventricular entrainment.