Closed loop stimulation reduces the incidence of atrial high-rate episodes compared with conventional rate-adaptive pacing in patients with sinus node dysfunctions.

AIMS: Subclinical atrial fibrillation (AF) is associated with increased risk of progression to clinical AF, stroke, and cardiovascular death. We hypothesized that in pacemaker patients requiring dual-chamber rate-adaptive (DDDR) pacing, closed loop stimulation (CLS) integrated into the circulatory control system through intra-cardiac impedance monitoring would reduce the occurrence of atrial high-rate episodes (AHREs) compared with conventional DDDR pacing. METHODS AND RESULTS: Patients with sinus node dysfunctions (SNDs) and an implanted pacemaker or defibrillator were randomly allocated to dual-chamber CLS (n = 612) or accelerometer-based DDDR pacing (n = 598) and followed for 3 years. The primary endpoint was time to the composite endpoint of the first AHRE lasting ≥6 min, stroke, or transient ischaemic attack (TIA). All AHREs were independently adjudicated using intra-cardiac electrograms. The incidence of the primary endpoint was lower in the CLS arm (50.6%) than in the DDDR arm (55.7%), primarily due to the reduction in AHREs lasting between 6 h and 7 days. Unadjusted site-stratified hazard ratio (HR) for CLS vs. DDDR was 0.84 [95% confidence interval (CI), 0.72-0.99; P = 0.035]. After adjusting for CHA2DS2-VASc score, the HR remained 0.84 (95% CI, 0.71-0.99; P = 0.033). In subgroup analyses of AHRE incidence, the incremental benefit of CLS was greatest in patients without atrioventricular block (HR, 0.77; P = 0.008) and in patients without AF history (HR, 0.73; P = 0.009). The contribution of stroke/TIA to the primary endpoint (1.3%) was low and not statistically different between study arms. CONCLUSION: Dual-chamber CLS in patients with SND is associated with a significantly lower AHRE incidence than conventional DDDR pacing.

Head-up tilt test diagnostic yield in syncope diagnosis.

BACKGROUND: The European Syncope Guidelines (ESG) recommend the use of Head-up tilt test (HUT) in case of suspicion of vasovagal syncope (VVS) or orthostatic hypotensive syncope (OHS) after an adequate initial inconclusive evaluation. We report a single center experience in the scenario of suspected VVS or OHS, who underwent HUT in patients referred to a Syncope Clinic after ruling out high-risk causes. METHODS: We prospectively and consecutively included all syncopal patients that were referred for HUT, by their attending physician after performing a series of diagnostic tests to rule out cardiac etiology. The clinical history and diagnostic tests performed were reviewed prior to HUT. Patients were pre-classified according to the recommendations from the ESG as; VVS, OHS or Syncope of Unknown Etiology (SUE). RESULTS: We studied 1058 patients, 558 (52.7%) males, mean age 46.5 ±â€¯20.1 yr. There were no gender differences in age, risk factors, previous heart diseases, ECG findings or number of previous tests. Based on the ESG criteria a significant number of diagnostic tests were probably unnecessarily performed. HUT was positive in 609 patients (57.5%). The rate of positive HUT according to pre-classification was significantly different among groups: 60% VVS, 46.1% OHS and 54.3% SUE (p = 0.037). Combining ESG recommendations and HUT results of the 1058 resulted in 762 (72%) diagnosed as VVS, 89 (8.4%) as OHS and 207 (19.5%) as SUE. CONCLUSIONS: Appropriate application of ESG recommendations combined with HUT, identified 81% of patients with non-cardiogenic syncope, potentially avoiding a significant number of unnecessary diagnostic tests.