The Dual Role of Implantable Loop Recorder in Patients with Potentially Arrhythmic Symptoms: a Retrospective Single-center Study

Background: Unexplained and potentially arrhythmic symptoms often lead to electrophysiology referral for evaluation. Implantable loop recorder (ILR) correlation of the symptom to the rhythm can secure a definitive arrhythmic diagnosis after a standard, yet nondiagnostic workup.

Methods: This large single-center retrospective study sought to assess the role of ILR in the evaluation of potentially arrhythmic symptoms, both in terms of diagnosis of an arrhythmia as well as to rule out an arrhythmic cause. Clinical data, indications for ILR, interrogation reports, and further management strategies were collected in all 86 patients who received ILR from June 1999 to April 2008 at the University of Iowa Hospitals and Clinics. The indications for ILR were unexplained syncope (76%), palpitations (14%), and presyncope or dizziness (10%).

Results: During a mean follow-up period of 10 +/- 7 months, 53 patients (62%) had recurrent symptoms after ILR placement with the mean time to recurrence of 12 +/- 17 weeks. Of these, an arrhythmic diagnosis was established in 12 patients (14%). Forty-one patients (48%) did not have any arrhythmia during their symptoms. These patients were discharged from the electrophysiology clinic. Thirty-three patients (38%) did not have any symptoms following ILR placement. Out of these, device was explanted in 10 patients, while the rest are still being followed.

Conclusions: In patients with potentially arrhythmic symptoms, ILR plays an important role not only in diagnosing an arrhythmia, but also to rule out an arrhythmic cause.