title: Consecutive administration of atropine and isoproterenol for the evaluation of asymptomatic sinus bradycardia.
abstract: OBJECTIVE
  Sinus node function is commonly evaluated by the atropine test. The isoproterenol test is less used. The aim of this study was to evaluate chronotropic reserve in patients with asymptomatic sinus bradycardia using the combined administration of atropine and isoproterenol.
  
  
  RESULTS
  A total of 100 patients were studied, 18-70 years old, with permanent, asymptomatic, sinus bradycardia and no detectable cardiac disease. The standard administration protocols for atropine and isoproterenol were used and successive heart rate recorded. Patients were stratified into three groups: Group A (control), showing normal response to atropine and isoproterenol; Group B, demonstrating abnormal response to atropine; Group C, with abnormal response to atropine and isoproterenol. No statistically significant difference was observed between Groups A and B (P = 0.11), whereas Group C differed statistically from both Groups A (P < 0.000001) and B (P = 0.000003) to a significant extent. By the end of the 3-year follow-up period, 47% of the Group C patients had undergone permanent pacemaker implantation (DDDR)--Kaplan-Maier survival curves predict only 35% survival without pacing--whereas none did so in Groups A and B.
  
  
  CONCLUSIONS
  In patients with deficient chronotropic response to atropine administration, isoproterenol tests could differentiate those with inadequate chronotropic reserves, possibly requiring preventive pacemaker implantations.
authors.affiliation: 1Cardiology Department, Thriasio General Hospital of Elefsina, G. Gennimatas Avenue, Elefsina, Athens, Greece. rvav1962@yahoo.gr
authors.forename: Spiridoula
authors.initials: S
authors.lastname: Vavetsi
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Nikolaou
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Tsarouhas
authors.forename: Georgios
authors.initials: G
authors.lastname: Lymperopoulos
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kouzanidis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kafantaris
authors.forename: Athanasios
authors.initials: A
authors.lastname: Antonakopoulos
authors.forename: Christina
authors.initials: C
authors.lastname: Tsitsimpikou
authors.forename: John
authors.initials: J
authors.lastname: Kandylas
mesh_terms: D000293:Adolescent; D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D001285:Atropine / Q000008:administration & dosage*; D001919:Bradycardia / Q000175:diagnosis*; D004562:Electrocardiography / Q000187:drug effects* / Q000379:methods*; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013566:Sympathomimetics / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D000889:Anti-Arrhythmia Agents; D013566:Sympathomimetics; D001285:Atropine; D007545:Isoproterenol