Differentiating atrioventricular nodal reentrant tachycardia from atrioventricular reentrant tachycardia by ΔHA values during entrainment from the ventricle

BackgroundDifferentiating atrioventricular nodal reentrant tachycardia (AVNRT) from orthodromic atrioventricular reentrant tachycardia (AVRT) can be difficult. The His bundle and atria are activated sequentially over the AV node during entrainment of AVNRT from the ventricle but simultaneously during supraventricular tachycardia (SVT). They are activated in parallel during entrainment of AVRT but sequentially during SVT.ObjectiveThe purpose of this study was to test the hypothesis that a ΔHA (HA(entrainment) – HA(SVT)) cutoff value of 0 reliably differentiates AVNRT from AVRT.Methods and ResultsOf 61 patients undergoing electrophysiologic evaluation for paroxysmal SVT, retrograde His-bundle potentials were recorded in 57 (93%) and entrainment performed in 49 (34 AVNRT, 15 AVRT). ΔHA values during entrainment from the ventricle were significantly longer during AVNRT than AVRT (31 ± 24 ms vs –38 ± 31 ms, P <.001). All ΔHA values were positive (minimum: 3 ms) for AVNRT and negative (maximum: –2 ms) for AVRT. ΔHA of 0 had sensitivity, specificity. and positive predictive value of 100% for correct diagnosis.ConclusionThe ΔHA criterion during entrainment of tachycardia from the ventricle reliably differentiates AVNRT (positive values) from AVRT (negative values).