Accelerated idioventricular rhythm (AIR)

Introduction

  • Accelerated idioventricular rhythm (AIR) occurs in patients with underlying heart disease such as coronary artery disease, it commonly manifests in patients with myocardial infarction

  • It can also occur in patients experiencing digoxin toxicity

  • Onset of AIR is generally gradual and occurs when the rate of AIVR exceeds the sinus rate as a result of sinus slowing or sinoatrial (SA) or AV block

  • Termination is also gradual and can happen due to slowing of the ventricular rate or acceleration of the sinus rhythm

  • SA node and the ventricles compete for the role of leading pacemaker due to their similar rate, that produces capture beats and/or fusion beats

  • It is usually transient lasting up to several minutes and can be recurrent

  • It does not alter the patient’s prognosis

Causes

  • Typical situation resulting in AIR is reperfusion of a blocked coronary artery such as during or after PCI for myocardial infarction

  • Other causes/situations include resuscitation (during return of spontaneous circulation), electrolyte abnormalities, congenital heart disease, cardiomyopathies, myocarditis or drug effect (isoprenaline, norepinephrine)

ECG characteristics

  • regular or irregular ventricular rhythm with a rate of 60-110/min
  • > 3 consecutive wide (>120 ms) QRS complexes
  • capture beats and fusion beats may be present

ECG 1 Accelerated idioventricular rhythm - a ventricular rhythm at a rate of 97/min, QRS duration is 136 ms, capture beats are present (last beat in limb and precordial leads)


Management

  • Treatment is rarely necessary. If treatment is required (symptomatic patient, rate is too high,…) atrial pacing or atropine administration to accelerate the sinus rhythm can be considered

References

  1. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 11th ed, Zipes DP, Libby P, Bonow RO, et al, W.B. Saunders Company, Philadelphia 2018.
  2. https://litfl.com/accelerated-idioventricular-rhythm-aivr/