Neurally Mediated Syncope and Arrhythmias

of syncope in patients with arrhythmias,1 evaluation of the syncope is important in determining an appropriate therapy [eg, pharmacological and/or nonpharmacological intervention (pacemaker, cardiodefibrillator implantation)]. Syncopal hypotension and/or bradycardia in neural circulatory control are thought to account for the neurally mediated syncope (NMS)2 that often accompanies various arrhythmias. Kenny et al3 reported that 36 patients still experienced fainting out of 147 syncopal patients with a pacemaker. It is suggested that the NMS is sometimes misjudged as Adams-Stokes syncope and artificial pacemaker therapy may be indicated. The head-up tilt test (HUT) is well known for stimulating NMS. 3 We investigated whether there were differences between patients with and without arrhythmias in the development of NMS and characterized NMS in syncopal patients with arrhythmia. We also used the HUT to assess the possibility that the arrhythmia may contribute to the generation of NMS.