Real-world utility of implantable loop recorders

Abstract

Abstract Background Implantable loop recorders (ILRs) allow prolonged and continuous single-lead electrocardiogram recording and have significantly shortened time to electrocardiographic diagnosis and appropriate therapy of many bradyarrhythmias and tachyarrhythmias. Purpose The aim of this retrospective single center study was to evaluate ILR indications, diagnostic yield and ILR-guided interventions. Methods We retrospectively analyzed 388 patients (223 male / 165 female), who underwent Medtronic and Biotronik ILRs implantation at a heart center. Demographic and clinical data were obtained from the medical records. Remote monitoring was analyzed when no data of in-hospital follow up could be acquired. Results The mean age at ILR implantation was 63.4 ± 14.9 years with a mean follow-up of 20.7±17.6 months from ILR implantation. In total, 152 (39.2%) patients were followed by a remote monitoring system. Number of patients with ILR indication due to syncope (n=171; 44.1%) was significantly higher compared to patients with monitoring after ablation of atrial fibrillation or atrial flutter (n=108; 27.8%), cryptogenic stroke (n=50; 12.9%) and presyncope and dizziness (n=21; 5.4%) (p<0.05). After 12 months, arrhythmia was detected in 198 cases (79.2% out of 250 patients with detected arrhythmias). The most common type of arrhythmia was paroxysmal atrial fibrillation (31.7%) with a significantly higher prevalence compared to atrial tachycardias (16.5%) and supraventricular premature beats (9.8%) (p<0.05). Noteworthy, in 132 (52.8% out of 250) patients, ILR diagnosis corresponded to the suspected arrhythmia, whereas in 118 patients unexpected arrhythmias were detected. ILR diagnosis of arrhythmia lead in 147 (58.8%) patients to initiation of a new therapy or to a change of current medication. Changes of current medication occurred in 72 patients (28.8%), electrophysiology study/ablation in 66 patients (26.4%), pacemaker/ICD implantation in 46 (18.4%), electrical cardioversion in 6 patients (2.4%), and closure of the left atrial appendage in 1 patient. Conclusion Our study shows, that ILRs are an important diagnostic tool, providing clinical relevant data in about two thirds (65%) of the patients. About half (52.8%) of the detected arrhythmia correlated with the symptoms leading to ILR implantation (number needed to treat was around 2). Remote monitoring improves the diagnostic timing with a potential reduction of costs for health care. However, patient selection is critical and ILRs benefits needs to be proven in larger randomized trials.