Abstract 10370: Personalised Approach is the Key When it Comes to Pacing a Patient with an S-ICD

Abstract

Introduction: Patients with an S-ICD may develop a pacing indication. When transvenous pacing is not feasible, the combination of an S-ICD and a leadless pacemaker (LP) might be a sound option. There are increased reports of concomitant use of LPs and S-ICDs. However, the effect of pacing on the S-ICD sensing is not well studied. Hypothesis: We hypothesize that pacing changes R and T waves morphology and amplitudes, causing changes in R:T ratios perceived by an S-ICD, increasing the risk for T wave oversensing (TWO) during paced rhythm with a subsequent risk of inappropriate shocks. Methods: We ran a prospective study in patients undergoing an electrophysiological study on clinical grounds. Participants were fitted with a Holter®, the leads of which placed to correspond to the three vectors of an S-ICD. We used a standard catheter to pace the right ventricle at four positions (figure 1) for 10 beats each at 8mA/2ms. We analysed the Holter® traces and used two-way ANOVA to assess the effect of pacing on the R:T ratio. Results: A total of 47 patients (mean age 56.02 ± 16.02,72% male) were enrolled (81% structurally normal heart, 15% DCM, 2% ICM, and 2% congenital heart disease). Age, sex, and aetiology had no effect on the R:T ratio. Pacing caused significant decrease in the R/T ratio, but there was no significant difference in the R/T ratio between different pacing sites. (P <0.001). (figure 2) Conclusions: Pacing- regardless of position- causes the S-ICD perceived R:T ratio to fall below the eligibility screening threshold in most patients, increasing the risk of TWO and inappropriate shocks. Caution needs to be exercised and tailored programming of both devices is key for concomitant use of LPs and S-ICDs.