Loading...
Neurocardiogenic syncope (NCS), the most common type of syncope, typically is benign and occurs in young individuals. However, its clinical course is highly variable, making therapeutic decisions and clinical trial design challenging. Prior studies of permanent pacemaker treatment for NCS demonstrated a profound placebo effect and are therefore difficult to interpret. Investigators have now published findings from ISSUE-3, a manufacturer-sponsored, blinded, European multicenter, randomized trial of pacing in NCS.
All patients were aged 40 or older and had experienced three or more episodes of NCS during the previous 2 years. In a 12-month prestudy screening phase, 511 patients received an implantable loop recorder; of these, 77 with syncope and asystole of 3 or more seconds or asymptomatic asystolic pauses of 6 or more seconds during follow-up received pacemakers and were randomized to pacing on or off. The 2-year syncope recurrence rate in the pacing-off group was 57%, compared with 25% in the pacing-on group (P=0.04).
Brignole M et al. Pacemaker therapy in patients with neurally mediated syncope and documented asystole: Third International Study on Syncope of Uncertain Etiology (ISSUE-3). A randomized trial. Circulation 2012 May 29; 125:2566.
Connolly SJ. Permanent pacemaker therapy for neurally mediated syncope. Circulation 2012 May 29; 125:2552.
Comment
According to this study, a pacemaker may be effective in a small group of older patients with severe neurocardiogenic syncope and asystole. This is consistent with my experience; older NCS patients are more likely than younger ones to have concomitant sinus node dysfunction and thus are more likely to benefit from pacing. However, as an editorialist cautions, these results should in no way open the floodgates for pacing in the overall population of patients with NCS. Appropriate candidates are patients with predominantly asystolic variants, particularly if they also have sinus node dysfunction.