title: Cardioinhibitory carotid sinus hypersensitivity: prevalence and predictors in 502 outpatients.
abstract: BACKGROUND
  Cardioinhibitory response (CIR) is defined as asystole >3 seconds in response to 5-10 seconds of carotid sinus massage (CSM). Pacemaker implantation is indicated for patients with unexplained syncope episodes and CIR.
  
  
  OBJECTIVE
  To determine the prevalence and predictors of CIR in patients with a high prevalence of cardiovascular disease, and assess the clinical significance of CIR in patients with a history of unexplained syncope or falls.
  
  
  METHODS
  Cross-section design study. Outpatients, aged > or =50 years, referred to the electrocardiography sector of a tertiary hospital. Those with dementia, carotid bruit, and history of myocardial infarction, stroke or transient ischemic attack in the preceding 3 months were excluded. CSM was performed by a single investigator, with the patients in the supine position. CSM was applied on the right side and then on the left side during 10 seconds each time.
  
  
  RESULTS
  502 patients underwent CSM. CIR was present in 52 patients (10.4%; 95% CI: 7.7%-13%). Independent predictors of CIR were male gender (OR: 2.61%; CI 95%: 1.3%-5.1%), structural heart disease (OR: 3.28%; CI 95%: 1.3%-7.9%) and baseline heart rate (P<0.05). The sensitivity of the CIR to CSM in syncope evaluation was low (9.8%). Specificity was high (89.5%), being even better in women (95.3%) and in those without structural heart disease (96.2%).
  
  
  CONCLUSIONS
  CIR was detected in 10.4% of the patients aged > or = 50 years. In males and in patients with structural heart disease CIR was more common. In women and patients with no apparent structural heart disease, the presence of CIR was a highly specific finding in the evaluation of syncope or falls.
authors.affiliation: Universidade Federal do Rio de Janeiro- Hospital Geral de Bonsucesso - Rio de Janeiro, RJ - Brazil. glacerda@cardiol.br
authors.forename: Gustavo de Castro
authors.initials: Gde C
authors.lastname: Lacerda
authors.forename: Roberto Coury
authors.initials: RC
authors.lastname: Pedrosa
authors.forename: Renato Côrtes de
authors.initials: RC
authors.lastname: Lacerda
authors.forename: Marcela Cedenilla dos
authors.initials: MC
authors.lastname: Santos
authors.forename: Maurício de Andrade
authors.initials: Mde A
authors.lastname: Perez
authors.forename: Alfredo Brasil
authors.initials: AB
authors.lastname: Teixeira
authors.forename: Aristarco Gonçalves de
authors.initials: AG
authors.lastname: Siqueira-Filho
mesh_terms: D000058:Accidental Falls / Q000706:statistics & numerical data; D000368:Aged; D001938:Brazil / Q000453:epidemiology; D002340:Carotid Artery Diseases / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D002346:Carotid Sinus / Q000503:physiopathology*; D004812:Epidemiologic Methods; D005260:Female; D006323:Heart Arrest / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D017678:Sex Distribution; D016683:Supine Position; D013575:Syncope / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology