International Study on Syncope of Uncertain Etiology 2: The management of patients with suspected or certain neurally mediated syncope after the initial evaluation rationale and study design

Objectives. Main objective is to verify the value of implantable loop recorder (ILR) in assessing the mechanism of syncope and the efficacy of the ILR-guided therapy after syncope recurrence. Inclusion criteria. Patients who met the following criteria are included: suspected or definite neurally mediated syncope based on initial evaluation; ≥3 syncope episodes in the last 2 years; severe clinical presentation of syncope requiring treatment initiation in the judgement of the investigator and age >30 years. Exclusion criteria. Patients with one or more of the following are excluded: carotid sinus syndrome; suspected or definite heart disease and high likelihood of cardiac syncope; symptomatic orthostatic hypotension diagnosed by standing blood pressure measurement; loss of consciousness different from syncope (e.g. epilepsy, psychiatric, metabolic, drop-attack, TIA, intoxication, cataplexy) and subclavian steal syndrome. End-points. The primary end-points are the ECG-documented syncopal events and the syncope recurrences after application of ILR-guided therapy. Sample size and duration. A minimum of 400 patients will be enrolled during an anticipated period of 3 years.