title: Predictors of atrial flutter with 1:1 conduction in patients treated with class I antiarrhythmic drugs for atrial tachyarrhythmias.
abstract: OBJECTIVE
  The purpose of the study was to look for the predictor factors of atrial proarrhythmic effects of class I antiarrhythmic drugs.
  
  
  BACKGROUND
  Class I antiarrhythmic drugs may induce or exacerbate cardiac arrhythmias. The predictors of ventricular proarrhythmia are known. The predictors of atrial flutter with 1:1 conduction are unknown.
  
  
  METHODS
  Clinical history, EGG, signal-averaged EGG (SAECG) and electrophysiologic study were analysed in 24 cases of 1:1 atrial flutter with class I AA drugs and in 100 control patients without history of 1:1 atrial flutter with class I AA drugs.
  
  
  RESULTS
  The ages of patients varied from 46 to 78 years. Underlying heart disease was present in nine patients. The surface EGG revealed the presence of a short PR interval (PR<0.13 ms), visible in leads V5, V6 in eight (35%) patients with normal P wave duration; in other patients with prolonged P wave duration, PR seemed normaL On SAECG recording, there was a pseudofusion between P wave and QRS complex. The electrophysiologic study revealed some signs indicating a rapid AV nodal conduction (short AH interval or rate of 2nd degree AV block at atrial pacing >200 beats/mm) in 19 of the 23 studied patients. All patients, except one, had at least one sign indicating a rapid AV nodal conduction (short PR and/or P wave-QRS complex continuity on SAECG). In the control group, seven patients (7%) had a short PR interval (P<0.01) and 11 (11%) had a pseudofusion between P wave and QRS complex on SAECG (P<0.001). The P wave-QRS complex pseudofusion on SAECG had a sensitivity of 100% and a specificity of 89% for the prediction of an atrial proarrhythmic effect with class I antiarrhythmic drug.
  
  
  CONCLUSIONS
  We recommend avoiding class I AA drugs in patients with a short PR interval on surface EGG and to record SAECG in those with apparently normal PR interval to detect a continuity between P wave and QRS complex, which could indicate a rapid AV nodal conduction, predisposing to 1:1 atrial flutter with the drug.
authors.affiliation: Cardiology, CHU of Brabois 54500 Vandoeuvre Les Nancy, France. b.brembilla-perrot@chu-nancy.fr
authors.forename: B
authors.initials: B
authors.lastname: Brembilla-Perrot
authors.forename: P
authors.initials: P
authors.lastname: Houriez
authors.forename: D
authors.initials: D
authors.lastname: Beurrier
authors.forename: O
authors.initials: O
authors.lastname: Claudon
authors.forename: A
authors.initials: A
authors.lastname: Terrier de la Chaise
authors.forename: P
authors.initials: P
authors.lastname: Louis
mesh_terms: D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects* / Q000494:pharmacology; D001281:Atrial Fibrillation / Q000188:drug therapy; D001282:Atrial Flutter / Q000139:chemically induced* / Q000175:diagnosis / Q000188:drug therapy; D018880:Atrial Premature Complexes / Q000188:drug therapy; D016022:Case-Control Studies; D000075202:Contraindications; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005544:Forecasting; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D000889:Anti-Arrhythmia Agents