Usefulness of an Implantable Loop Recorder in Patients with Syncope of an Unknown Cause

Purpose: The mechanisms underlying syncope remain unknown in about 20% of patients with recurrent syncope. The implantable loop recorder (ILR) has been shown to be a useful diagnostic tool in patients with unexplained syncope even after negative initial evaluations. Nevertheless, ILR has rarely been used in clinical practice. Materials and Methods: This study included 18 consecutive patients who had an ILR implanted at our center because of recurrent unexplained syncope after extensive diagnostic tests between February 2006 and June 2011. Results: Diagnosis was confirmed in 10 (55.6%) of the 18 enrolled patients (13 males, 61 +/- 15 years). The confirmed diagnoses included sick sinus syndrome (n=6, 60%), advanced atrioventricular block (n=2, 20%) and ventricular tachyarrhythmia (n=2, 20%). The mean follow-up durations of the total study subjects and the diagnosed patients were 11.3 +/- 10.6 months and 5.6 +/- 9.2 months, respectively. Of the 10 diagnosed patients, 8 (80%) were diagnosed within 6 months of loop recorder implantation. Conclusion: ILR may be a valuable and effective diagnostic tool for patients with unexplained syncope.