In a trial of 46 adults with frequent vasovagal syncope (VVS), dual-chamber pacing with closed loop simulation (DDD-CLS) significantly reduced recurrent episodes when compared to sham DDI mode pacing.

The proportion of patients that cut their syncopal episodes at least in half was 72 percent with DDD-CLS pacing and 28 percent in the sham mode. In addition, a statistical estimate revealed the time to first relapse was 29.2 months with DDD-CLS pacing versus 9.3 months in the placebo arm.

“Although a smaller sample contributed data for the primary efficacy outcome of at least a 50% reduction in burden of syncope, the effect was clear and highly significant, indicating that DDD-CLS pacing is highly beneficial in a population of patients with recurrent, high-burden VVS,” wrote lead researcher Gonzalo Baron-Esquivias, MD, from Universidad de Sevilla in Spain, and colleagues.

They published their findings in the Journal of the American College of Cardiology.

“This benefit was further supported by the highly significant effect (89% relative risk reduction) in the time to first recurrence of syncope. Time to first recurrence of syncope correlates well with frequency of syncope, which may be more clinically relevant from the patient’s perspective and for health care resource utilization.”

The authors pointed out previous studies have been inconclusive regarding the efficacy of pacing to prevent VVS, and some have demonstrated a strong placebo effect.

Their study included 24 women and 22 men, all older than 40, who had experienced at least five VVS episodes, including at least two the year before the trial. Participants also demonstrated a cardioinhibitory response to a head-up tilt test, defined as heart rate lower than 40 beats per minute for at least 10 seconds or asystole for at least three seconds.

Patients were randomized to either DDD-CLS pacing for 12 months followed by sham DDI mode pacing at 30 pulses per minute for another 12 months, or the reverse order of those interventions. They were given a diary to document all syncopal or pre-syncopal episodes during the follow-up period.

Baron-Esquivias and colleagues pointed out the study did not compare DDD-CLS mode with other dual-chamber pacing modes, so further trials may be warranted to determine the best option to recommend to patients.