Cardinal ECG Features and Treatment

The cardinal ECG features treatment:

  • Rate over 100
  • P waves present, before QRS (antegrade) but shape may be abnormal (Fig 1) (distinguishes it from sinus tachycardia)
  • In focal atrial tachycardia there will be a consistent abnormal P wave, whilst multifocal atrial tachycardia will have multiple different P wave morphologies
  • R-P baseline isoelectric (distinguishes it from AF)
Figure 1.5 Focal atrial tachycardia (FAT): Consistent, abnormal P wave morphology indicating an ectopic focus.


DC cardioversion is likely to terminate the tachycardia, but some rhythms may recur.

Evidence for specific drug therapy is poor, with beta-blockers, calcium channel blockers and most anti-arrhythmic drugs having potential roles. Adenosine may diagnose the rhythm but is unlikely to terminate it.
Beta-blockers & calcium channel blockers may be used first-line for chronic therapy of recurrent episodes, with catheter ablation the definitive treatment of choice.