P911Universal S-ICD eligibility: eliminating the need for pre-implant screening using mathematical vector rotation and a gradient filter

S-ICD eligibility is determined by ECG morphology across three sensing vectors; primary (P), secondary (S) and alternate (A). Small R:T ratios and low amplitude signals confer an unacceptable risk of oversensing and are unsuitable. The vector score is a composite measure of signal amplitude and R:T ratio calculated using an S-ICD simulator. Eligibility requires a single vector to score > 100. Around 5% of ICD patients have no suitable vector, this rises to 13-16% in some patient groups (ACHD, hypertrophic cardiomyopathy). Mathematical vector rotation is a novel technique which can generate vectors, at any given angle of observation, using signal recorded in the current S-ICD position. Vector rotation alters the relative amplitudes of both R and T such that for any individual, the largest R wave vector (Rmax) and the smallest T wave vector (Tmin) can be generated. We hypothesise that combining these signals, using a gradient filter to identify periods of rapidly changing signal amplitude, will significantly increase both R:T ratio and vector scores. Application of this programming to a cohort of patients, who are currently S-ICD ineligible, has the potential to produce universal device eligibility.