Accelerated Idioventricular Rhythm (AIVR)

Introduction

Accelerated idioventricular rhythm (AIVR) is a type of heart rhythm disturbance originating from the ventricles. It is generally considered a benign arrhythmia, but in some cases, it may indicate underlying heart conditions.

What is AIVR?

AIVR is a slow ventricular arrhythmia with a heart rate typically between 50–110 beats per minute (bpm). It occurs when an ectopic ventricular pacemaker overrides the sinus node. It is most commonly observed in: - Reperfusion after myocardial infarction (one of the most frequent causes). - Drug effects, such as digoxin toxicity. - Electrolyte imbalances, particularly hypoxia or hypokalemia. - Congenital heart diseases or cardiomyopathies.

Symptoms

Most patients do not experience significant symptoms. However, in some cases, individuals may develop: - Palpitations (a feeling of irregular or fast heartbeat). - Dizziness or lightheadedness. - Mild chest discomfort.

Diagnosis

The primary tool for diagnosis is an electrocardiogram (ECG), which shows: - A regular or slightly irregular rhythm. - Wide QRS complexes (>120 ms), similar to ventricular tachycardia. - Absence of P waves (or they may be dissociated from the QRS complexes). - Rate between 50 and 110 bpm.

Is AIVR Dangerous?

AIVR is often self-limiting and resolves without treatment, particularly after myocardial reperfusion. However, it is important to differentiate it from more severe arrhythmias like ventricular tachycardia (VT) or ventricular fibrillation (VF).

Treatment

• No treatment is needed in hemodynamically stable patients (those with normal blood pressure and circulation).
• If symptomatic, addressing the underlying cause is the key (e.g., correcting electrolyte imbalances, managing ischemia, or adjusting medications).
• In rare cases, atropine may be used if bradycardia causes significant symptoms.
• Avoid antiarrhythmic drugs like amiodarone, as they may worsen the condition.

Summary

AIVR is typically a benign arrhythmia, often seen in myocardial infarction recovery. It usually does not require treatment unless the patient is symptomatic. The key is identifying and managing underlying causes.

Related Clinical Guidelines

• American College of Cardiology Guidelines on Arrhythmias
• European Society of Cardiology Guidelines on Ventricular Arrhythmias

Source recommendations

1. American College of Cardiology Guidelines on Arrhythmias

1. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001193
2. https://www.acc.org/Clinical-Topics/Arrhythmias-and-Clinical-EP
3. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000549
4. https://www.acc.org/Guidelines
5. https://pubmed.ncbi.nlm.nih.gov/29097320/

2. European Society of Cardiology Guidelines on Ventricular Arrhythmias

1. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death
2. https://academic.oup.com/eurheartj/article/43/40/3997/6675633
3. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000549
4. https://pubmed.ncbi.nlm.nih.gov/36017572/
5. https://www.sciencedirect.com/science/article/pii/S2405500X22010945