Triggered by a sudden drop in blood pressure and heart rate, leading to a reduction in blood flow to the brain, syncope can be very dangerous due to loss of consciousness.1 It is a common problem, with a frequency of between 15% and 39%.2 Syncope can severely affect many people’s quality of life, particularly since these episodes recur and are unpredictable.3 The mediated neural reflex, known as neurocardiogenic or vasovagal syncope, is the most frequent cause of syncope.2 Pacemakers are used widely to address heart rhythm disorders, especially bradycardia. The pacing programme known as Closed Loop Stimulation (DDD-CLS) treats recurrent syncope by detecting contractions than precede an episode of syncope, preventing the potentially dangerous fall in heart rate and blood pressure.
Patients who received the DDD-CLS pacing programme experienced significantly fewer fainting episodes compared to a placebo (DDI) pacing group, according to the recent results of the Closed Loop Stimulation for Neuromediated Syncope (SPAIN) study (n=46).4 During the two-year trial, four patients receiving DDD-CLS pacing experienced syncope versus 21 who received DDI pacing, which, unlike DDD-CLS, does not respond to the contractions preceding syncope.
The average age of patients in the SPAIN study was 56 years and 48% were men. To be eligible, patients had to have experienced more than five episodes of syncope over their lifetime, with more than two in the past year. Patients were randomly assigned to receive either DDD-CLS or DDI pacing for 12 months after which the two programmes were switched. However, if a patient in either group had more than three episodes of syncope in one month, their pacing assignment was switched. Among those patients who were initially assigned to DDD-CLS pacing, 72.2% experienced a reduction of more than 50% in syncope episodes, but fainting recurred when they crossed over to the DDI group after the first year.
SPAIN is the first prospective double-blind placebo-controlled trial to show robustly positive results for the DDD-CLS pacing program in patients with recurrent syncope. The lack of treatments available for recurrent syncope underlines the significance of this study, according to the study’s lead investigator, Gonzalo Baron-Esquivias, associate professor, chief of the clinical cardiology section and head of studies in the cardiology department at Virgen del Rocio University Hospital in Seville, Spain.
‘Now a door is open and we have new possible treatment for these patients,’ Baron-Esquivias said.
The main limitations of this study are the small size and short duration of follow-up. However, if the findings of SPAIN are confirmed by larger, ongoing studies such as the Benefit of Dual-chamber Pacing With Closed Loop Stimulation (CLS) in Tilt-induced Cardioinhibitory Reflex Syncope (BIOSync CLS) trial (ClinicalTrials.gov Identifier: NCT02324920), Baron-Esquivias expects international guidelines will be changed to recommend DDD-CLS pacing for patients with recurrent syncope.
The SPAIN study was funded by the Investigation Agency of the Spanish Society of Cardiology, which received an unrestricted grant from Biotronic Spain. Biotronic is the developer of the DDD-CLS programme.
1. Ruwald MH, Epidemiological studies on syncope--a register based approach, Dan Med J, 2013;60:B4702.
2. da Silva RM, Syncope: epidemiology, etiology, and prognosis, Front Physiol, 2014;5:471.
3. Kenny RA, McNicholas T, The management of vasovagal syncope, QJM, 2016;109:767–73.
4. Baron-Esquivias G, Randomized placebo controlled trial of closed loop stimulation in recurrent reflex vasovagal syncope (SPAIN study), Presented at: American College of Cardiology Scientific Session, 19 March 2017, Washington, DC, US.