Efficacy of implantable loop recorders in establishing symptom-rhythm correlation in young patients with syncope and palpitations

Objective. To evaluate efficacy of the recently introduced implantable loop recorder (ILR) in establishing symptom-rhythm correlation in young patients with syncope, near syncope, palpitations, and acute life-threatening events (ALTEs). Methods. A retrospective study was conducted with patients with ILR from 3 pediatric centers. Inclusion criteria were age less than or equal to 25 years and a minimum follow-up of 1 month. All ILR-stored events were analyzed regularly for the presence or absence of an arrhythmia at the time of the symptomatic event. Results. Twenty-one patients ( 12 male, 9 female) with an average age of 12.3 +/- 5.3 years ( range: 0.8 - 22 years) were included in the study. Five (24%) patients had structural heart disease, 2 (10%) had a family history of sudden cardiac death, 3 (14%) had QT prolongation on electrocardiogram, and 11 had no cardiovascular disease. Indications for ILR were recurrent syncope and near syncope ( n = 15), palpitations ( n = 2), and ALTE ( n = 2). Fourteen (67%) patients continued to have symptoms, and 7 (33%) had no symptoms after ILR over a follow-up period of 8.4 +/- 4.7 months ( range: 1.9 - 16 months). Symptom-rhythm correlation was possible in all 14 patients who continued to have symptoms ( supraventricular tachycardia in 4, ventricular tachycardia in 2, torsades de points in 1, asystole in 1, junctional bradycardia in 1, and sinus rhythm in 5). Conclusions. ILR is useful in determining the presence or absence of an arrhythmia during symptoms of syncope, near syncope, and palpitations as well as ALTEs in patients with and without structural heart disease when conventional diagnostic testing, such as electrocardiogram, Holter monitoring, and/or external loop recording, is inconclusive.