International study on syncope of uncertain aetiology 3 (ISSUE 3): pacemaker therapy for patients with asystolic neurally-mediated syncope: rationale and study design

Eligible patients receive an Implantable Loop Recorder and are followed till the first documented syncopal recurrence or a significant asystolic event. Those patients who have an asystolic pause (sinus arrest or AV block) > 6 s or a syncopal asystolic pause > or = 3 s receive a dual-chamber pacemaker implantation and are randomized to active therapy (Pm ON) or to placebo therapy (Pm OFF). End-points: Primary end-point is the first syncope recurrence after pacemaker implant. Sample size and duration: A maximum of 710 patients are to be enrolled during an anticipated period of 2 years to allow randomization of 60 patients in the Pm ON arm and 60 in the Pm OFF arm (total 120).