(CCSP046) HIS REFRACTORY PACING MANEUVERS TO SIMPLIFY THE DIAGNOSIS OF ACCESSORY PATHWAY-MEDIATED SUPRAVENTRICULAR TACHYCARDIAS INVOLVING THE ATRIUM AND VENTRICLE FOR THE ARRHYTHMIA CIRCUIT

Background: Numerous diagnostic studies can be performed to help correctly identify and differentiate the different types of supraventricular tachycardias (SVT) in the electrophysiology (EP) laboratory. However, certain arrhythmia mechanisms yield overlapping diagnostic results that make SVT differentiation challenging, such as in cases of atrioventricular reciprocating tachycardia (AVRT) and atypical atrioventricular nodal reentrant tachycardia (AVNRT). Moreover, many pacing maneuvers have poor sensitivity or are difficult to perform during an EP study. This study aimed to test a pacing maneuver that can be easily performed, with the potential to be consistently diagnostic for most cases of AVRT. We hypothesize that simultaneous delivery of a premature ventricular contraction (PVC) and a left lateral premature atrial contraction (PAC) during His-refractoriness will always terminate or affect AVRT while rarely, if ever, terminate or affect other supraventricular tachyarrhythmias such as AVNRT.

METHODS AND RESULTS: Pilot, single-centre prospective study of adult patients who underwent an electrophysiology study with or without ablation for SVT from January to April 2023. Patients without sustained SVT during EP study were excluded. During SVT, simultaneous His-refractory PVC and His-refractory PAC (in the lateral left atrium using the distal coronary sinus electrode) were delivered. His-refractory PVC only and His-refractory PAC only were done as comparators. Other usual EP study results, including the diagnoses, were collected.

Nineteen patients with a preliminary diagnosis of SVT were enrolled. Five were excluded (4 due to no sustained SVT during the study, 1 due to incorrectly delivered pacing maneuvers). Of the 14 patients, 4 had AVRT (3 using a left lateral accessory pathway and 1 using a R posterolateral accessory), 9 had typical AVNRT, and 1 had atrial tachycardia (AT). Simultaneous His-refractory PVC and left lateral PAC terminated all the AVRTs while they did not have any effect on the other types of SVTs. In contrast, His-refractory PVC did not affect any of the AVRTs. His-refractory PAC terminated 1 AVRT with a L lateral accessory pathway. None of the maneuvers affected AVNRT or AT.

Conclusion: In this pilot study of patients with SVT, simultaneous delivery of a His-refractory PVC and left lateral PAC during SVT consistently terminated AVRT, with no effect on AVNRT or AT. While the sample size is very limited, the results of our study show that this maneuver is feasible and may be helpful in differentiating between AVRT and AVNRT, with more consistent and easily interpretable effects on AVRT compared to His-refractory PVCs alone.