title: Cardioinhibitory carotid sinus hypersensitivity predicts an asystolic mechanism of spontaneous neurally mediated syncope.
abstract: OBJECTIVE
  We correlated the finding of cardioinhibitory carotid sinus hypersensitivity (CSH) with that observed during a spontaneous syncopal relapse by means of an implantable loop recorder (ILR).
  
  
  RESULTS
  We included 18 consecutive patients with suspected recurrent neurally mediated syncope and positive cardioinhibitory response during carotid sinus massage (max pause 5.5 +/- 1.6 s) who had subsequent documentation of a spontaneous syncope by means of an ILR. They were compared with a 2:1 age- and sex-matched group of 36 patients with a clinical diagnosis of recurrent neurally mediated syncope and negative response to carotid sinus massage, tilt testing and ATP test. Asystole >3 s was observed at the time of the spontaneous syncope in 16 (89%) of CSH patients and in 18 (50%) of the control group (P = 0.007). Sinus arrest was the most frequent finding among CSH patients but not among controls (72 vs. 28%, P = 0.003). After ILR documentation, 14 CSH patients with asystole received dual-chamber pacemaker implantation; during 35 +/- 22 months of follow-up, 2 syncopal episodes recurred in 2 patients (14%), and pre-syncope occurred in another 2 patients (14%). Syncope burden decreased from 1.68 (95% confidence interval 1.66 - 1.70) episodes per patient per year before to 0.04 (0.038-0.042) after pacemaker implant (98% relative risk reduction).
  
  
  CONCLUSIONS
  In patients with suspected neurally mediated syncope, the finding of cardioinhibitory CSH predicts an asystolic mechanism at the time of spontaneous syncope and, consequently, suggests a possible benefit of cardiac pacing therapy.
authors.affiliation: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Via don Bobbio 24, 16033 Lavagna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Maggi
authors.forename: Carlo
authors.initials: C
authors.lastname: Menozzi
authors.forename: Michele
authors.initials: M
authors.lastname: Brignole
authors.forename: Cristian
authors.initials: C
authors.lastname: Podoleanu
authors.forename: Matteo
authors.initials: M
authors.lastname: Iori
authors.forename: Richard
authors.initials: R
authors.lastname: Sutton
authors.forename: Angel
authors.initials: A
authors.lastname: Moya
authors.forename: Franco
authors.initials: F
authors.lastname: Giada
authors.forename: Serafino
authors.initials: S
authors.lastname: Orazi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Grovale
mesh_terms: D000241:Adenosine; D000368:Aged; D001283:Atrioventricular Node / Q000187:drug effects*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012804:Sick Sinus Syndrome / Q000175:diagnosis*; D012849:Sinoatrial Node / Q000187:drug effects*; D019462:Syncope, Vasovagal / Q000175:diagnosis*; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine