The Value of Programmed Ventricular Extrastimuli From the Right Ventricular Basal Septum During Supraventricular Tachycardia

BACKGROUND The difference between the right ventricular (RV) apical stimulus-atrial electrogram (SA) interval during resetting of supraventricular tachycardia (SVT) versus the ventriculoatrial (VA) interval during SVT (DSA-VAapex) is an established technique for discerning SVT mechanisms but is limited by a significant diagnostic overlap. OBJECTIVES This study hypothesized that the difference between the RV SA interval during resetting of SVTs versus the VA interval during SVTs (DSA-VA) would yield a more robust differentiation of atrioventricular nodal re-entrant tachycardia (AVNRT) from atrioventricular reciprocating tachycardia (AVRT) when using the RV basal septal stimulation (DSA-VAbase) as compared to the RV apical stimulation (DSA-VAapex). Moreover, it was predicted that the DSA-VAbase might distinguish septal from free wall accessory pathways (APs) effectively. METHODS In this prospective study, 105 patients with AVNRTs (age 48 +/- 20 years, 44% male) and 130 with AVRTs (age 26 +/- 18 years, 54% male) underwent programmed ventricular extrastimuli delivered from both the RV basal septum and RV apex. The DSA-VA values were compared between the 2 sites. RESULTS The DSA-VAbase was shorter than the DSA-VAapex during AVRT (44 +/- 30 ms vs 58 +/- 29 ms; P < 0.001), and the opposite occurred during AVNRT (133 +/- 31 ms vs 125 +/- 25 ms; P = 0.03). A DSA-VAbase ofS85 milliseconds had a sensitivity of 97% and specificity of 96% for identifying AVNRT. Furthermore, a DSA-VAbase of 45-85 milliseconds identified AVRT with left free wall APs (sensitivity 86%, specificity 95%), 20-45 milliseconds for posterior septal APs (sensitivity 72%, specificity 96%), and <20 milliseconds for right free wall or anterior/mid septal APs (sensitivity 86%, specificity 98%). CONCLUSIONS The DSA-VAbase during programmed ventricular extrastimuli produced a robust differentiation between AVNRT and AVRT regardless of the AP location with S85 milliseconds as an excellent cutoff point. This straightforward technique further allowed localizing 4 general AP sites. (c) 2023 by the American College of Cardiology Foundation.