Use of an Implantable Loop Recorder in Different Age Groups to Identify the Cause of Unexplained Syncope

Background. An implantable loop recorder (ILR) is a small subcutaneous electrocardiogram monitoring device that may be useful in the diagnosis of patients with recurrent syncope or palpitations, while initial examination is not diagnostic. Objectives. To analyze the use of an ILR in different age groups and identify its effectiveness in determining the cause of syncope. Material and methods. This single -center retrospective study included 51 patients who underwent ILR implantation at the Hospital of the Lithuanian University of Health Sciences Kaunas Clinics due to unexplained syncope between January 2015 and July 2022. Patients were divided into two groups according to age: younger (< 50 years, n = 26) and older (>= 50 years, n = 25). Results. The mean duration to diagnosis of arrhythmia -related syncope was 219 [105-995] days in the younger patients and 141 [30-452] days in the older patients ( p = 0.28). In younger patients, the diagnoses were sinus node dysfunction (SND) ( n = 3), complete atrioventricular (AV) block ( n = 1), and ventricular tachycardia (VT) ( n = 1), while in older patients - SND ( n = 4), complete AV block ( n = 2), fast supraventricular tachycardia (SVT) ( n = 1), and VT ( n = 1). In younger patients, 4 (80%) were offered a pacemaker and 1 (20%) an implantable cardioverter-defibrillator implantation, while in older patients, the recommendations were more heterogeneous: 6 (75%) were offered a pacemaker, 1 (12.5%) an catheter ablation, and 1 (12.5%) an electrophysiological study. The documented incidence of arrhythmia -related syncope was not statistically significant different between the groups (19.2% vs 32.0%, p = 0.30). Conclusions. An ILR is a useful instrument in determining the causes of recurrent unexplained syncope in different age groups.