Predictors of atrial flutter with 1:1 conduction in patients treated with class I antiarrhythmic drugs for atrial tachyarrhythmias

Int J Cardiol. 2001 Aug;80(1):7-15. doi: 10.1016/s0167-5273(01)00459-4.


Objectives: 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.

Conclusion: 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.

MeSH terms

  • Adult
  • Aged
  • Anti-Arrhythmia Agents / adverse effects*
  • Anti-Arrhythmia Agents / pharmacology
  • Atrial Fibrillation / drug therapy
  • Atrial Flutter / chemically induced*
  • Atrial Flutter / diagnosis
  • Atrial Flutter / drug therapy
  • Atrial Premature Complexes / drug therapy
  • Case-Control Studies
  • Contraindications
  • Electrocardiography / methods*
  • Female
  • Forecasting
  • Heart Conduction System / drug effects*
  • Humans
  • Male
  • Middle Aged
  • Patient Selection*
  • Prospective Studies
  • Sensitivity and Specificity
  • Signal Processing, Computer-Assisted


  • Anti-Arrhythmia Agents