Efficacy of a Right-sided Ablation of the Anterior Ganglionated Plexus for Neurally Mediated Syncope

The third study on CardNM (CardNMH3 study) is a multicenter, double-blind, randomized trial with a sham control group investigating the efficacy and safety of a computed tomography (CT)-guided, right-sided ablation of the anterior ganglionated plexus to prevent recurrence of syncope in patients with neurally mediated syncope (NMS). The primary goal of the study is to determine whether a CT-guided, right-sided ablation of the anterior ganglionated plexus safely reduces the risk of recurrent episodes of syncope in patients with a history of recurrent NMS. Two-third of the patients will be randomized to the active arm and one-third to the control arm (sham). The study procedure is described in the 'detailed description' and 'intervention description'. Syncope burden, syncope occurrence and quality of life will be assessed by questionnaires at baseline and at 1, 3, 6 and 12 months. A 24-h rhythm registration will be performed at baseline and at 1-, 3- and 6-month follow-up to investigate the influence of the intervention on heart rate. The effect of CardNM on blood pressure and on chronotropic sinus node function will be evaluated in 2 additional substudies. Patients enrolled in the blood-pressure substudy will undergo a 24-h blood pressure monitoring at baseline and at 1, 3 and 6 months. Participants in the sinus node competence substudy will undergo a bicycle exercise test at baseline and at 1, 3 and 6 months. Investigators aim to achieve complete follow-up for 110 patients who meet the study enrollment criteria. If syncope-free survival (primary endpoint) is significantly different between the 2 arms after the enrollment of fewer than 110 patients (minimum 55 patients), enrollment into the trial will be prematurely stopped. The study may also be terminated prematurely if safety concerns occur.