B-PO01-084 DIAGNOSTIC UTILITY OF EARLY PREMATURE VENTRICULAR COMPLEXES IN DIFFERENTIATING ATRIOVENTRICULAR REENTRY AND AV NODE REENTRY TACHYCARDIAS

Abstract

His refractory PVC (HrPVC) perturbing a supraventricular tachycardia (SVT) establishes the presence of an accessory pathway (AP). Earlier PVCs may perturb AVNRT or AVRT and are currently considered non-diagnostic. We hypothesize that an early PVC will always show a minimum differential of >30 ms in its advancement of AVNRT because of minimum retrograde conduction time (stimulus to His plus His to AV node) of 30 ms from any ventricular pacing site to the AV node. The site of pacing, on the other hand, can be in close proximity to some AVRT circuits resulting in greater advancements. Thus, if an early PVC (H1S2) advances the subsequent atrial activation (A1-A2) more than this minimum differential (A1A2 ≤ H1S2+30 ms), AVRT diagnosis is established. Thirty-seven consecutive patients with either AVNRT or AVRT undergoing ablation were retrospectively evaluated. PVCs were delivered during SVT at RV apex or septum based on operator preference. Early PVCs were defined when the pacing stimulus was >30 ms ahead of the His. When early PVCs resulted in A1A2 ≤ H1S2+30 ms, it was considered an AP response. Final diagnosis of AVRT and AVNRT, based on tachycardia features and standard established maneuvers, were matched to the above responses by an observer blinded to the diagnosis. Among the 38 cases, 21 were AVNRT (20 typical, 1 atypical) and 17 were AVRT (2 right free wall, 2 right septal, 1 left septal, 12 left free wall). SVTs were divided into those with the AP response and those without AP response to early PVCs. Eight cases had an AP response with a mean H1S2+30 ms of 333 ± 60 ms and A1A2 of 307 ± 56 ms, and all cases were confirmed AVRT. The specificity of AP response to early PVC in predicting AVRT was 100%. The sensitivity of the test to predict AVRT was low, 45%. No AVNRT cases had AP response. All 9 AVRTs without an AP response were left free wall. An AP response to early PVCs (A1A2 ≤ H1S2+30 ms) is 100% specific for AVRT diagnosis. The degree of atrial advancement after early PVCs may contain information to differentiate AVRT and AVNRT in select cases.