Single Lead Implantable Cardioverter Defibrillator (ICD) with a Floating Atrial Dipole: A Systematic Review and Non-Comparative Meta-Analysis

Background: A DX implantable cardioverter defibrillator (ICD) system consists of an ICD and a shock lead equipped with two ring electrodes positioned in the atrium, referred to as the DX-lead. This system allows the collection of atrial signals using a single lead. Multiple studies on the device have been conducted over more than a decade. Aims: The aim of this study is to summarise these data in a non-comparative meta-analysis. Methods: A systematic literature review targeting publications on studies including a certain type of ICD, VR-DX ICD, was conducted. Subsequently a meta-analysis of proportions was conducted. Endpoints selected for evaluation included p-wave amplitude (at day 0, <6 months, 6-12 months and >12 months), appropriate and inappropriate shock rates, and all-cause mortality. Results: One randomised controlled trial, 11 prospective cohort studies and registries, and two retrospective studies were selected for analysis. P-wave amplitudes were consistently in a range where they can support clinical decision making across studies and remained stable over a follow-up of up to two years. Pooled shock incidence was consistent with industry standard for appropriate (10.7%) and inappropriate shocks (2.4%) across studies. All-cause mortality was at an average of 5%, increasing, as expected, with duration of study follow-up. Like shock results, mortality was within the expected range. Conclusion: This analysis shows that the VR-DX ICD system works reliably and provides an added benefit compared to single chamber ICD in the form of atrial sensing. Atrial view without requiring a second lead provides clinicians with an attractive, hardware-sparing option for the continuous monitoring of atrial activity.