Rhythm Nation August 2014 Answer!

by eabram • August 15, 2014 • Comments Off

Best and most thorough and most correct reading goes to… Dr. Freedman!

The major clue to this case is the recent or evolving STEMI. In the era of thrombolysis for STEMI, the Accelerated Idioventricular Rhythm (AIVR) or Accelerated Ventricular Rhythm was often seen after reperfusion. Now that PCI is more commonly used than thrombolysis, it’s not as frequently seen in the ED.

The proposed mechanism involves an enhanced automaticity of a ventricular pacemaker which can supersede the sinus node, often in the setting of increased vagal tone with decreased sympathetic tone.

How to diagnose AIVR? A regular rhythm, wide-complex QRS complex, and rate between 50 and 110 beats per minute. If the rate is slower than 50, it is a Ventricular Escape Rhythm. Faster than 110, it is a Ventricular Tachycardia. Fusion beats or capture beats may also be seen.

While acute MI is the most common cause, other causes can be considered: beta-sympathomimetics, stimulants such as cocaine, digoxin, volatile inhaled anesthetics, post-ROSC, cardiomyopathy and electrolyte abnormalities.

Treatment? Keep the patient on a monitor, and don’t address the rhythm directly. Anti-arrhythmics do not help this patient. DO treat any underlying causes (dig toxicity, electrolyte correction).

What now? Outside of the ED, AIVR has more recently been examined in the context of PCI as a possible prognostic factor. Terkelsen et al monitored 490 patients during PCI and AIVR was the most common arrhythmia (41%). Of the patients with AIVR, the authors concluded this rhythm was associated with increased residual myocardial damage post-MI as indicated by higher peak troponin T, longer time to ST elevation resolution and larger final infarct size measured by myocardial perfusion scan 1 month post-MI.

By Dr. Elizabeth Abram, supervised by Dr. Jennifer Martindale.

For more images and other excellent discussions:

Dr. Smith’s ECG Blog

Life in the Fast Lane

References:

Martindale, JL, Brown, DFM. Rapid Interpretation of ECGs in Emergency Medicine. Lippincott Williams & Wilkins (2012).

Mattu, A, Brady W. ECGs for the Emergency Physician 2, BMJ Books (2008).

Osmancik, P et al, In-hospital Arrythmias in Patients with Acute Myocardial Infarction – the Relation to the Reperfusion Strategy and their Prognostic Impact. Acute Cardiac Care. 2008; 10: 15-25.

Terkelsen, CJ et al, Prevalence and Significance of Accelerated Idioventricular Rhythm in Patients With ST-Elevation Myocardial Infarction Treated With Primary Percutaneous Coronary Intervention. American Journal of Cardiology: 2009; 104(12): 1641-1646.

The views expressed on this blog are the author's own and do not reflect the views of their employer. Please read our full disclaimer here. Any references to clinical cases refer to patients treated at a virtual hospital, Janus General Hospital.