During 2016 and 2017, 5 papers have been published on recurrent vasovagal syncope with cardioinhibitory response to the tilt table test (TTT) and treatment with pacemaker implantation.
The first paper reported on a single center, retrospective, observational study of 24 patients with recurrent syncope. An in-depth diagnostic protocol was applied, including a TTT and exclusion of any other cause for syncope, followed by insertion of an implantable loop recorder (ILR). When patients then had a first syncope recurrence accompanied by asystole longer than 3 seconds or asystole longer than 6 seconds irrespective of syncope recurrence, they received a dual-chamber pacemaker with rate drop response (RDR). In the 35-month follow-up, syncope recurred in 7 patients, 4 of whom were TTT-positive. However, of the 17 patients without syncope recurrence, the TTT was positive in only 2.1
The second paper described a prospective, multicenter study with 281 patients older than 40 years who underwent a diagnostic study starting with carotid sinus massage (CSM). Of these patients, 78 had asystole and were given an implantable PM. The remaining 203 patients underwent a TTT. A VASIS type 2B response with asystole was induced in 38 patients, who were then given an implantable PM. The remaining 165 patients received an ILR. Asystole was recorded in 21 of these patients, who were then given an implantable PM. All 137 patients treated with a PM received a dual-chamber device with rate drop sensing to allow minimal ventricular pacing time. Syncope recurred in 25 of the 281 patients (18%), and there were no differences according to the test (CSM, TTB or ILR) that indicated PM requirement. At 3 years of follow-up, 20% of the 137 patients with a PM had had syncope recurrence, which was significantly lower than the 43% in the 142 patients who received no PM (P=.01). Among the patients who had asystole during the TTT, syncope recurrence was 3% at 12 months and 17% at 21 months. Among the patients with a negative TTT, syncope recurrence was only 5% at 3 years.2
The third paper reported on a multicenter, prospective, single-blind, randomized study that enrolled 30 patients with a dual-chamber PM with closed-loop stimulation (CLS) implanted at least 6 months prior to enrolment, with a history of recurrent syncopes and cardioinhibitory response to the TTT. At the initial visit, patients were randomized 1:1 by a central system into 1 of 2 pacing groups, DDD-CLS first or DDD first (at a fixed rate of 60 bpm), and they underwent a first TTT with the PM activated. At the end of the test, the PM was reprogrammed and 1 week later, the test was repeated with the other pacing mode, i.e., with crossover from DDD-CLS to DDD and from DDD to DDD-CLS. Compared with DDD, the DDD-CLS mode significantly reduced the occurrence of syncope in the TTT (30.0% vs 76.7%; P <.001). Among the patients who had a syncope in both TTTs and with both pacing modes, DDD-CLS significantly delayed the onset of syncope during TTT. The maximum fall in blood pressure recorded during the TTT was significantly lower in DDD-CLS than in DDD.3
The fourth paper described the SPAIN study, with a multicenter, prospective, randomized, double-blind design, that enrolled 54 patients with recurrent syncope and TTT cardioinhibitory response. A total of 46 patients completed the protocol. All patients received a DDD-CLS PM and were randomized 1:1 to 2 groups: group A first received DDD-CLS for 12 months and then DDI for 12 months; group B first received DDI and then DDD-CLS for the same periods of time as group A. During 22 months of follow-up, in group A, 72% of patients receiving DDD-CLS therapy had ≥ 50% reduction in syncopes versus 28% of patients receiving DDI; and in group B, all patients had ≥ 50% reduction in syncopes after switching from DDI mode to DDD-CLS in the second year (P=.0003). Just 4 patients (8.7%) had a syncope when in DDD-CLS mode, versus 21 (45.65%) who had one when in DDI mode (hazard ratio=6.72; odds ratio=0.11; P <.0001). The Kaplan-Meier analysis showed significantly longer time to first syncope in group A versus group B and the same finding was also observed in the 46 patients in DDD-CLS mode versus DDI mode (P <.0001). Therefore, DDD-CLS pacing significantly reduces syncope burden, lowers syncope recurrence 7-fold, and significantly prolongs time to first recurrence.4,5 The BIOSync study, 6the fifth paper referred to here, aims to confirm our results.
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