PARA-HISIAN PACING DURING SINUS RHYTHM: DERIVING FORMAL VALUES TO DETERMINE THE PRESENCE OF A SEPTAL ACCESSORY PATHWAY

Abstract

Para-Hisian pacing during sinus rhythm is an established method to evaluate for the presence of a septal accessory pathway (AP). Despite being an accepted diagnostic maneuver, formal values to differentiate nodal versus extra-nodal conduction have not been established. We sought to evaluate the change in stimulation-to-atrial electrogram interval measured from the proximal coronary sinus (delta-stim-PCS) with His-bundle plus para-Hisian ventricular (H+V) capture and para-Hisian ventricular (V) capture alone among patients with a septal AP and those with no AP. High and low output para-Hisian pacing during sinus rhythm was performed in patients undergoing an electrophysiology study to capture H+V or V, respectively. Stim-PCS intervals were measured and the within patient difference for V and H+V capture was calculated. Normally distributed continuous variables were compared using the Student’s t-test Among 23 and 41 patients with a septal AP and no AP, respectively, the delta-stim-PCS was shorter in patients with a septal AP (1918 ms vs. 6521 ms, p<0.001). The shortest delta-stim-PCS observed with no AP was 37 ms, while the longest delta-stim-PCS observed in the presence of a septal AP was 51 ms. Patients possessing a septal AP exhibited a shorter delta-stim-PCS interval relative to individuals with no AP. A delta-stim-PCS less than 37ms confirmed the presence of a septal AP, while a value greater than 51ms excluded its presence.