Real-world evaluation of the treatment yield of implantable loop recorders (ILR) in the Netherlands

Abstract

Abstract Background Implantable loop recorders (ILRs) are invasive and expensive diagnostic tools used to determine the underlying arrhythmias associated with syncope and palpitations as well as capture atrial fibrillation (AF). The diagnostic and treatment yield from ILRs is uncertain. Prior studies indicated that 26-52% ILR patients were diagnosed with arrhythmias and 11-30% received subsequent treatment. Purpose Our primary aim was to determine the incidence of pacemaker and ICD implants within 1- and 3- years of ILR implantation. The secondary aims include 1) an evaluation of the incidence of AF ablation, 2) the identification of predictors for treatment, and 3) safety. Methods Adult patients who underwent an ILR implant in the Netherlands Heart Registration (NHR) Pacemaker and ICD registry (2018-2021) were included. The NHR device registry was linked to the ablation registry to determine the incidence of AF ablation after ILR. Incidence rates for pacemaker implants, ICD implants, AF ablations, and complications among ILR patients were reported as a proportion of ILR patients over 1- and 3- years. Predictors for treatment following an ILR were determined from multivariable logistic regression models. Results From 2018 to 2021, 11,961 patients underwent an ILR implant in the Netherlands. Patients who underwent ILR implantation were a median age 69 (IQR 56-77) years, 46.9% female, and 24.9% had AF. The most frequent indication for ILR implantation was syncope (76.2%), followed by palpitations (15.2%). At 1- and 3-years post-ILR implantation, 12.0% and 14.6% of ILR patients underwent a pacemaker implant, respectively (Figure 1). Fewer patients underwent ICD implants (0.9% and 1.3%) and AF ablation (1.3% and 1.8%) at 1- and 3-years post-ILR implantation, respectively (Figure 1). Compared to males, females were 28% and 70% less likely to undergo a pacemaker and ICD implant following ILR, respectively (Figure 2). Additional predictors for pacemaker implantation included older age, AF, and syncope (p<0.05 for all, Figure 2a). In addition to female sex, AF was a predictor of ICD implantation (Figure 2b). The incidence of complications was relatively low (0.3%). Infection was the most frequent complication (0.2%), followed by device dislocation (0.06%), bleeding (0.02%), and device defect (0.01%). Conclusion Despite the benefits of ILRs for long-term remote monitoring, the therapeutic yield of ILRs is relatively low with 14.6%, 1.3%, and 1.8% of ILR patients undergoing implantation for pacemakers, ICDs, and AF ablation at 3-years follow-up. As an expensive and invasive diagnostic tool, a more targeted approach for referrals is warranted to increase the therapeutic yield of the ILRs. Further investigations are warranted to determine the diagnostic yield of ILRs, regardless of subsequent invasive therapy.