title: Atrial fibrillation threshold predicted long-term efficacy of pharmacological treatment of patients without structural heart disease.
abstract: OBJECTIVE
  To ascertain if an electrophysiological study could predict long-term efficacy of anti-arrhythmic drugs in the treatment of lone atrial fibrillation.
  
  
  RESULTS
  Forty-four patients (36 males, 8 females, age 55.5 +/- 10.6) with paroxysmal atrial fibrillation were enrolled to undergo serial electrophysiological studies at the bedside. Two quadripolar catheters were inserted via the subclavian vein. Disopyramide (D: 2 mg/kg iv), cibenzoline (C: 1.4 mg/kg iv), aprindine (A: 2 mg/kg iv), pilsicainide (P: 2 mg/kg po) and flecainide (F: 3 mg/kg po) were tested. Atrial fibrillation threshold (AFT) was measured as the lowest current amplitude of rapid pacing (50 Hz for 1 s) to induce atrial fibrillation lasting more than 30 s. Before drug treatment, AFT was 3.9 +/- 0.3 mA. Pharmacological treatment raised AFT as follows: D 5.9 +/- 0.9 mA, C 7.6 +/- 1.2 mA, A 8.1 +/-1.1 mA, P 6.0 +/- 0.8 mA, F 7.3 +/- 1.1 mA. Recurrence of atrial fibrillation was observed during 1-year follow-up in 12% of cases when they were treated with a drug that raised AFT by 5 mA or more. On the other hand, the recurrence rate was 87% when patients were treated with a drug that raised AFT by less than 5 mA (P = 0.001).
  
  
  CONCLUSIONS
  AFT was a good predictor of long-term efficacy of pharmacological treatment against atrial fibrillation.
authors.affiliation: Kyoto Prefectural University of Medicine, Second Department of Medicine, Kawaramachi Hirokoji, Japan. sirayama@koto.kpu-m.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Shirayama
authors.forename: H
authors.initials: H
authors.lastname: Shiraishi
authors.forename: S
authors.initials: S
authors.lastname: Yoshida
authors.forename: Y
authors.initials: Y
authors.lastname: Matoba
authors.forename: H
authors.initials: H
authors.lastname: Imai
authors.forename: M
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001073:Aprindine / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D004206:Disopyramide / Q000627:therapeutic use; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005424:Flecainide / Q000627:therapeutic use; D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D007093:Imidazoles; D001073:Aprindine; D008012:Lidocaine; C042288:pilsicainide; D004206:Disopyramide; D005424:Flecainide; C032151:cifenline