Dual-chamber pacing with closed loop stimulation reduces syncope recurrence in patients with cardioinhibitory vasovagal syncope and ≥ 2 syncopal events in 1 year
EBM Focus - Volume 12, Issue 43
- Limited evidence is available as to whether pacemaker therapy decreases syncope recurrence in patients with cardioinhibitory vasovagal syncope.
- The efficacy of DDD-closed loop stimulation (CLS) pacing vs. sham (DDI mode) pacing to reduce syncope recurrence was investigated in a randomized crossover trial with 54 adults ≥ 40 years old with recurrent vasovagal syncope (≥ 2 events in 1 year) and a positive tilt test.
- The rate of patients experiencing a ≥ 50% reduction in syncopal episodes over 1 year was 72% with DDD-CLS pacing vs. 28% with sham pacing (p = 0.017, NNT 3).
Vasovagal syncope (also called reflex syncope) is a common type of syncope that may be due to predominantly cardioinhibitory or hypotensive mechanisms (or both). Evidence regarding whether pacemaker therapy decreases syncope recurrence is limited. In trials comparing active vs. inactive pacemaker programming, two small trials did not show a statistically significant difference in syncope recurrence in patients who had a cardioinhibitory response to tilt testing (J Am Coll Cardiol 1999, JAMA 2003) and one trial (ISSUE-3) demonstrated a benefit for active programming in patients with documented asystole (Circulation 2012). A recent randomized crossover trial evaluated DDD-CLS pacing vs. sham (DDI mode) pacing in 54 adults ≥ 40 years old with recurrent vasovagal syncope. All patients had a positive tilt test and history of ≥ 5 episodes of vasovagal syncope with ≥ 2 episodes (median 4.5 episodes) in the past year. After 12 months, the patients were crossed over to the alternate treatment for 12 months unless 3 syncopal episodes occurred within 1 month of enrollment; in which case, crossover was immediate. The analysis was performed in the 85% of patients that completed the trial.
The rate of patients experiencing a ≥ 50% reduction in syncopal episodes over 1 year was 72% with DDD-CLS pacing vs. 28% with sham pacing (p = 0.017, NNT 3). In addition, fewer patients with DDD-CLS pacing had ≥ 1 syncopal episode (in 8.7% vs. 46% with sham pacing, p < 0.05, NNT 3) and the median time to the first syncopal episode was not reached in the DDD-CLS group while it was 9 months in the sham group (p < 0.0001). Procedural complications included transitory atrial arrhythmia in 3 patients and atrial lead dislodgement in 1 patient.
The SPAIN trial demonstrated a benefit in reducing syncope recurrence with DDD-CLS pacing compared to sham (DDI mode) pacing in patients with recurrent vasovagal syncope and a positive tilt test. These findings are consistent with the ISSUE-3 trial conducted in 77 patients with recurrent syncope and documented asystole (Circulation 2012). The authors of the SPAIN trial note that the event rate was too low to investigate whether there were differences in benefit of pacemaker therapy between patients who have bradycardia versus asystole on tilt testing. Due to the potential risks associated with pacemaker implantation, there is further need to better define the patient population who would most benefit from dual chamber pacemaker therapy, as the rate of syncope recurrence in the active arm of the SPAIN trial was 8% over one year and 25% over 2 years in the ISSUE-3 trial. The ongoing BIOSYNC trial (Trials 2017) with a planned recruitment of 128 patients and two year follow-up may help answer this question. In summary, the SPAIN trial, along with the ISSUE-3 trial, suggest that dual chamber pacing (DDD mode) with closed loop stimulation is beneficial to reduce syncope recurrence in patients with recurrent cardioinhibitory vasovagal syncope.