Makindo Medical Notes

🫀 Accelerated Idioventricular Rhythm (AIVR) is a transient ventricular rhythm often seen post-MI, particularly during reperfusion. It is usually benign, self-limiting, and haemodynamically well tolerated, so treatment is rarely required. The key challenge is distinguishing it from slow VT or CHB.

📖 About

• Commonly observed after reperfusion in acute MI (PCI or thrombolysis).
• Often resembles a "slow VT" but is not typically malignant.
• Most cases resolve spontaneously as sinus rate accelerates past the ventricular focus.
• Generally requires only observation and reassurance unless instability develops.

📊 ECG Characteristics

• Broad-complex rhythm, usually regular.
• Rate: 40–120 bpm (classic: 60–100). 🕒
• AV dissociation often present (cannon A waves may be seen clinically).
• At rates >110–120 bpm, consider slow VT instead.

🧾 Differential Diagnosis

• CHB with escape rhythm: if rate <50 bpm.
• Slow VT: if rate >110–120 bpm, particularly in scarred ventricles.
• Junctional rhythm with aberrancy: consider if QRS morphology varies.

⚠️ Causes / Associations

• 💔 Acute STEMI, especially reperfusion arrhythmia.
• Ischaemic heart disease, cardiomyopathy.
• Myocarditis, digoxin toxicity (check K⁺ and drug levels).
• Cocaine use.
• Normal finding in well-trained athletes (high vagal tone).
• During ROSC after cardiac arrest.

🩺 Clinical Features

• Often asymptomatic, may have variable heart sounds due to AV dissociation.
• Seen in acute MI context → always check for associated complications.
• Usually haemodynamically stable (key teaching pearl: instability is unusual).

💊 Management

• Observation only in most cases – treat the underlying condition (e.g., MI).
• Spontaneously resolves once sinus node regains dominance.
• Do NOT suppress with antiarrhythmics (lidocaine, amiodarone) unless unstable – risk of asystole ⚠️.
• Seek senior input if in doubt, particularly in the peri-MI setting.

📚 References

• LITFL – Accelerated Idioventricular Rhythm
• NCBI Bookshelf – Idioventricular Rhythm

Cases — Accelerated Idioventricular Rhythm (AIVR)

• Case 1 — Post-Reperfusion MI: A 58-year-old man is admitted with an acute anterior STEMI. He undergoes primary PCI with stenting of the LAD. An hour later, telemetry shows a wide-complex rhythm at 70 bpm with gradual onset and offset. He is asymptomatic, BP stable, and the rhythm spontaneously reverts to sinus. Diagnosis: AIVR following reperfusion therapy for MI. Management: No treatment needed — benign rhythm. Monitor and continue post-MI care (dual antiplatelets, beta-blocker, ACEi, statin).
• Case 2 — Digoxin Toxicity: A 72-year-old woman with atrial fibrillation on digoxin presents with nausea and visual halos. ECG: regular wide-complex rhythm at 60 bpm, independent of atrial activity. Serum digoxin level high. Diagnosis: AIVR associated with digoxin toxicity. Management: Stop digoxin, correct electrolytes (especially potassium and magnesium), consider digoxin-specific antibody fragments if severe. Continuous cardiac monitoring until rhythm resolves.

Teaching Commentary ⚡

AIVR is a ventricular rhythm faster than the intrinsic ventricular escape rate (≈40 bpm) but slower than VT (usually 50–110 bpm). It typically occurs after reperfusion of acute MI (a “reperfusion arrhythmia”), but also in drug toxicity (digoxin), cardiomyopathy, and metabolic disturbances. ECG shows a regular, wide-complex rhythm with gradual onset/offset. Unlike VT, AIVR is benign and self-limiting, rarely requiring treatment. Management is to treat the underlying cause (e.g. reperfusion, stop digoxin, correct electrolytes) rather than antiarrhythmics.