Demonstration of syncope in patients after pacemaker implantation: role of head-up tilt test to distinguish neurocardiogenic vasodepressor syncope from pacemaker syndrome.

It is important to distinguish clinically neurocardiogenic syncope from pacemaker syndrome in patients after pacemaker implantation. We report two syncopal patients with AV sequential physiological pacemakers who displayed neurocardiogenic vasodepressor syncope (VDS) during head-up tilt (HUT) testing. Neurocardiogenic VDS, as a cause of syncope in patients following pacemaker implantation, might be involved in these patients as well as pacemaker syndrome. HUT is a useful diagnostic test in distinguishing neurocardiogenic VDS from pacemaker syndrome in patients with syncope following pacemaker implantation. Careful evaluations for diagnosis of pacemaker syndrome are needed in these patients.