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

Differentiating 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.The purpose of this study was to test the hypothesis that a DeltaHA (HA((entrainment)) - HA((SVT))) cutoff value of 0 reliably differentiates AVNRT from AVRT.Of 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). DeltaHA values during entrainment from the ventricle were significantly longer during AVNRT than AVRT (31 +/- 24 ms vs -38 +/- 31 ms, P <.001). All DeltaHA values were positive (minimum: 3 ms) for AVNRT and negative (maximum: -2 ms) for AVRT. DeltaHA of 0 had sensitivity, specificity. and positive predictive value of 100% for correct diagnosis.The DeltaHA criterion during entrainment of tachycardia from the ventricle reliably differentiates AVNRT (positive values) from AVRT (negative values).