Implantable loop recorder is an effective diagnostic tool for unexplained syncope

INTRODUCTION: Patients with cardiac syncope have a significantly higher mortality than patients with syncope of non-cardiac causes, while patients with syncope of unknown aetiology constitute an intermediate risk group, presumably because this group is mixed, which suggests that further diagnostic testing is warranted. MATERIAL AND METHODS: This was a retrospective single-centre study evaluating the diagnostic yield of an implantable loop recorder (ILR) in establishing the cause of recurrent, unexplained syncope. RESULTS: A total of 44 patients received ILR between 2007 and 2011. Follow-up data were available for 39 patients, the mean age was 63 years (range 23-94 years), 59% were female and the mean follow-up period was 349 days. The average time to first recurrence of syncope with ECG documentation was 244 days (range 11-699 days). The mean follow-up for the total population was 349 days (range 11-1,083 days) and for the group without recurrence 460 days (range 176-1,083 days). Diagnoses were obtained in 22 patients (56%) of which the cause of syncope was cardiac in 64%. CONCLUSION: ILR was an effective tool to establish an arrhythmic cause of the recurrent, unexplained syncope, and useful in ruling out arrhythmia as a cause of syncope. New studies are needed to demonstrate whether very prolonged monitoring in case of absent recurrence may further improve the diagnostic yield. Additionally, there is much need for randomized controlled trials to investigate whether ILR-guided therapy reduces recurrence rate and mortality.