Early application of an implantable loop recorder allows effective specific therapy in patients with recurrent suspected neurally mediated syncope

Aims: This prospective multicentre observational study assessed the efficacy of specific therapy based on implantable loop recorder (ILR) diagnostic observations in patients with recurrent suspected neurally mediated syncope (NMS). Methods and results: Patients with three or more clinically severe syncopal episodes in the last 2 years without significant electrocardiographic and cardiac abnormalities were included. Orthostatic hypotension and carotid sinus syncope were excluded. After ILR implantation, patients were followed until the first documented syncope (Phase I). The ILR documentation of this episode determined the subsequent therapy and commenced Phase II follow-up. Among 392 patients, the 1-year recurrence rate of syncope during Phase I was 33%. One hundred and three patients had a documented episode and entered Phase II: 53 patients received specific therapy [47 a pacemaker because of asystole of a median 11.5 s duration and six anti-tachyarrhythmia therapy (catheter ablation: four, implantable defibrillator: one, anti-arrhythmic drug: one)] and the remaining 50 patients did not receive specific therapy. The 1-year recurrence rate in 53 patients assigned to a specific therapy was 10% (burden 0.07 ± 0.2 episodes per patient/year) compared with 41% (burden 0.83 ± 1.57 episodes per patient/year) in the patients without specific therapy (80% relative risk reduction for patients, P =0.002, and 92% for burden, P = 0.002). The 1-year recurrence rate in patients with pacemakers was 5% (burden 0.05 ± 0.15 episodes per patient/year). Severe trauma secondary to syncope relapse occurred in 2% and mild trauma in 4% of the patients. Conclusion: A strategy based on early diagnostic ILR application, with therapy delayed until documentation of syncope allows a safe, specific, and effective therapy in patients with NMS.