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Pacing in Severe Recurrent Reflex Syncope and Tilt-Induced Asystole
Quick Takes
- In patients ages ≥40 years, affected by severe recurrent reflex syncope and tilt-induced asystole, dual-chamber pacemaker with closed loop stimulation (CLS) is effective in reducing the recurrences of syncope.
- After a median follow-up of 11.2 months, syncope occurred in significantly fewer patients in the pacing group than in the control group (16% vs. 53%; hazard ratio, 0.23; p = 0.00005).
Study Questions:
Do patients with severe recurrent reflex syncope and asystole induced by tilt testing benefit from closed loop stimulation (CLS) pacing?
Methods:
Patients ages ≥40 years with ≥2 episodes of severe reflex syncope in a year and a tilt-induced syncope with an asystolic pause longer than 3 seconds were randomly assigned to receive either an active (pacing ON; 63 patients) or an inactive (pacing OFF; 64 patients) dual-chamber pacemaker with CLS. The primary endpoint was the time to first recurrence of syncope.
Results:
After a median follow-up of 11.2 months, syncope occurred in significantly fewer patients in the pacing group than in the control group (10 [16%] vs. 34 [53%]; hazard ratio, 0.23; p = 0.00005). The estimated syncope recurrence rate at 1 year was 19% (pacing) and 53% (control) and at 2 years, 22% (pacing) and 68% (control). A combined endpoint of syncope or presyncope occurred in significantly fewer patients in the pacing group (23 [37%] vs. 40 [63%]; hazard ratio, 0.44; p = 0.002). Minor device-related adverse events were reported in five patients (4%).
Conclusions:
In patients ages ≥40 years, affected by severe recurrent reflex syncope and tilt-induced asystole, dual-chamber pacemaker with CLS is highly effective in reducing the recurrences of syncope. Our findings support the inclusion of tilt testing as a useful method to select candidates for cardiac pacing.
Perspective:
During vasovagal syncope, patients usually experience a combination of bradycardia (cardioinhibitory response) and hypotension (vasodepressor response). These are likely mediated by parasympathetic activation and sympathetic inhibition. Prior studies of pacing with rate drop response algorithms in vasovagal syncope had variable results. A significant placebo effect was found, necessitating all patients in randomized studies of vasovagal syncope to undergo device implantation with only the active treatment arm programmed to pace. The present study utilizes CLS, in which the pacemaker continuously analyzes right ventricular intracardiac impedance in order to ascertain the force of myocardial contraction and adjust pacing rate accordingly. The ISSUE-3 study found that patients with vasovagal syncope who have 6-second asystole on implantable loop recorder benefit from pacing algorithm with CLS. The current study shows that 3-second asystole during tilt testing may also identify patients who benefit from the proprietary algorithm.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure
Keywords: Arrhythmias, Cardiac, Bradycardia, Electric Impedance, Heart Arrest, Heart Failure, Hypotension, Myocardial Contraction, Pacemaker, Artificial, Secondary Prevention, Syncope, Syncope, Vasovagal, Tilt-Table Test
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