The Use of an Implantable Loop Recorder in Patients With Syncope of Unknown Origin

Background and Objectives: Possible mechanisms of syncope often remain unknown despite the performance of extensive cardiological and neurological tests. An implantable loop recorder (ILR) has been introduced to monitor the heart rhythm continuously over a year. We evaluated the diagnostic value of the use of the ILR for unexplained syncope. Subjects and Methods: Between 2006 and 2007, an ILR was implanted in 9 patients (7 male, 2 female, mean age 55±17 years) where syncope remained unexplained after extensive diagnostic tests. We analyzed the recorded electrocardiogram signal in the memory of the ILR. Results: During a follow-up period of 8.8±7.3 months, arrhythmia was detected in five patients. Two patients had a sinus pause and received a permanent pacemaker, and one patient had sustained ventricular tachycardia and fibrillation and received an implantable cardioverter defibrillator. One patient had micturition syncope with sinus pause and is waiting for permanent pacemaker implantation, and one patient had symptomatic paroxysmal atrial fibrillation and was administered anticoagulation therapy. Inappropriate auto-activations such as a pseudopause or a decreasing signal were also noted. Conclusion: ILR monitoring seems to be a useful diagnostic tool to identify the arrhythmic cause in patients with unexplained syncope. (Korean Circ J 2008;38:205-211)