Implantable loop recorder: towards a gold standard for the diagnosis of syncope?

Implantable loop recorder: towards a gold standard for the diagnosis of syncope? Role of the implantable loop recorderAn implantable ECG event monitor has recently become available (Reveal, Medtronic).This device is placed subcutaneously under local anaesthesia, and has a battery life of 15-18 months.The device has a solid state loop memory and, with the current version, the ECG of up to 40 minutes before and two minutes after activation can be stored.With these characteristics, if patients activate the device when consciousness has been restored, there is a high probability of having a correlation of ECG signals and syncope.In the first reported experience, the device was used in a heterogeneous population of 85 patients aVected by unexplained syncope, 1 which included patients with and without structural heart disease as well as patients with and without abnormalities in baseline ECG.Syncope-ECG correlation was achieved in 27% of patients and presyncope-ECG correlation in 32%; the rhythm recorded during the event was heterogeneous, thus reflecting the various clinical settings of the population enrolled: 29 patients were in sinus rhythm, three had supraventricular tachycardia, and 18 had some type of "bradyarrhythmia", the origin of which was considered to be neurally mediated in seven patients.This study showed that patient activated, long term monitoring is feasible, helpful, safe, and probably cost eVective.From that initial experience it appeared that the implantable loop recorder might become the reference standard to be adopted when an arrhythmic cause of syncope is suspected but not suYciently proven.There are several areas of interest:x Tilt induced vasovagal syncope-We do not know whether the type of response induced during tilt testing (vasodepressor, mixed, cardioinhibitory) correlates with the spontaneous vasovagal attack.Knowing the exact mechanism of the spontaneous attack is of course of great practical importance in choosing the best treatment.One recent trial 2 has shown that pacemaker therapy is highly eYcacious in preventing syncopal recurrences in patients with cardioinhibitory vasovagal syncope.