Background: In many patients with recurrent neurocardiogenic syncope (NCS), a significant fall in blood pressure precedes any appreciable decline in heart rate. Closed-loop pacing (CLS) employs a sensing system that measures myocardial contractility, thereby providing a potential way to detect the onset of NCS at a much earlier point in time than that provided by standard pacing systems.
Methods: Patients were included in the study if they suffered from recurrent NCS and met all of the following criteria: (1) They had suffered at least two syncopal episodes in the preceding 6 months. (2) Patients were refractory to (or intolerant of) all conventional, non-pharmacological, or pharmacological treatments. (3) They had evidence of asystole (>10 s) or severe bradycardia (heart rate <30 bpm) on implantable loop recorder or during head-up tilt test (HUTT).
Results: Thirty five patients meeting the above criterion received 44 devices. Twelve patients received a standard unit (with rate drop or rate hysterisis response) and 32 patients received a CLS unit (Cylos, Biotronik). The pacemaker implantation was termed successful if there was no recurrence of syncope, if the syncope burden decreased by > or =50%, if only presyncope occurred, or if the syncope occurred but with significant warning symptoms. Thirty-five patients, 29 females and six males, age 41 +/- 11, with refractory NCS underwent pacemaker implantation. Mean follow-up was 9 +/- 3 months. Out of 32 patients who received CLS, nine had a conventional pacemaker implanted in the past. Recurrence (59% vs 83%), reduction in syncope burden and pacemaker success (84% vs 25%, P = 0.002), and occurrence prodrome/warning signs (40% vs 16%) were much better in the closed-loop group.
Conclusion: These preliminary observations suggest that dual-chamber CLS pacing may be promising therapy for refractory NCS. Further randomized trials will be needed to better determine the role of this therapy in refractory NCS.