Digital twin to assess VF undersensing risk in concomitant leadless micra and extravascular ICD

Concomitant use of a leadless pacemaker and the Aurora extravascular implantable cardioverter-defibrillator (EV-ICD) provides a combined pacing and defibrillation therapy option without transvenous leads. However, device interaction may lead to ventricular fibrillation (VF) undersensing due to detection of pacing pulses. The aim of this research is to develop and validate a digital twin to simulate EV-ICD sensing behaviour in the presence of leadless pacing and quantify VF undersensing risk. Saline tank and animal experiments were conducted across multiple device configurations and pacing outputs. These data were used to train a model predicting EV-ICD sensed pacing amplitudes. Monte Carlo simulations were performed to estimate population-level risk. The model accurately estimated sensed amplitudes and identified device proximity and pacing pulse width as key determinants of undersensing risk. Increasing pulse width from 0.24 ms to 1 ms at 3 V increased risk from 4.6% to 37.3%. Model predictions correlated well with saline measurements; an adjustment factor was required to account for tissue differences in animal experiments. The digital twin framework showed good predictive performance in the saline tank and, after adjustment, performed well in animal models. These results suggest, that with further validation, this approach may support clinical assessment of VF undersensing risk in leadless device combinations.