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2018 ACLS Focused Update Takeaways - Antiarrhythmic Drugs

In November 2018, the American Heart Association (AHA) published a focused update for cardiopulmonary resuscitation and emergency cardiovascular care. Specifically, the update provided the most recent evidence for the use of antiarrhythmic drugs during and after ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT).

Antiarrhythmic drugs are used in shock refractory VF/pVT to assist in successful defibrillation and to prevent patients from converting back into a lethal rhythm. Shock refractory VF/pVT is defined as VF or pVT that continues or recurs after one shock.

It is important to note that no antiarrhythmic drugs have proven to increase long-term survival or produce survival with good neurological outcomes. The two most important practices that have improved survival after cardiac arrest are cardiopulmonary resuscitation (CPR) and defibrillation. These two items should not be delayed for an attempt to obtain an intravenous (IV) line for antiarrhythmic drug administration.

ACC/AHA Recommendation System: Applying Class of Recommendation and Level of Evidence to Clinical Strategies, Interventions, Treatments, or Diagnostic Testing in Patient Care* (Updated August 2015)

During VF/pVT Cardiac Arrest

The three antiarrhythmic drugs that were highlighted for use during a VF/pVT arrest are amiodarone, lidocaine, and magnesium.

Amiodarone updated recommendation: Amiodarone may be considered for VF/pVT patients who are unresponsive to defibrillation. This may be more effective in a witnessed arrest, compared to an unwitnessed arrest (Class IIB; Level of Evidence B-R).

Amiodarone is available in the United States in two formulations. One formulation is made with the diluent polysorbate, which can cause hypotension. This version can be given via IV push. The other formulation contains Captisol and does not cause hypotension. The Captisol formulation is produced in a premixed bag for infusion and cannot be given through an IV push.

Lidocaine updated recommendation: Lidocaine may be considered for VF/pVT patients who are unresponsive to defibrillation. It may be more effective in a witnessed arrest, compared to an unwitnessed arrest (Class IIB; Level of Evidence B-R).

Lidocaine is an antiarrhythmic that has been used for many years in healthcare and is familiar to most providers.

Magnesium updated recommendation: The routine use of magnesium for cardiac arrest is not recommended in adult patients (Class III: No Benefit; Level of Evidence C-LD). Magnesium may be considered for torsades de pointes (Class IIb; Level of Evidence C-LD).

After VF/pVT Cardiac Arrest

The two antiarrhythmic drugs that were highlighted for use immediately after ROSC (return of spontaneous circulation) after VF/pVT arrest are beta-blockers and lidocaine.

Beta-blocker updated recommendation: There is insufficient evidence to support or refute the routine use of a beta-blocker early (within the first hour) after ROSC.

The use of beta-blockers after ROSC can have both positive and negative effects. Beta-blockers can reduce ischemic injury and may stabilize the cell membrane. They also blunt the catecholamine activity that can lead to cardiac arrhythmias. Conversely, IV beta-blockers can worsen hemodynamic stability, exacerbate heart failure, and cause bradyarrhythmias.

Lidocaine updated recommendation: There is insufficient evidence to support or refute the routine use of lidocaine early (within the first hour) after ROSC. In the absence of contraindications, the prophylactic use of lidocaine may be considered in specific circumstances (medical transport) when treatment of recurrent VF/pVT might prove to be challenging (Class IIb; Level of Evidence C-LD).

Lidocaine was not shown to increase survival when administered prophylactically after ROSC. However, while it did not improve survival, it did reduce the recurrence of VF/pVT. This could be helpful if the patient needed to be transported via EMS (emergency medical services). This reduction in the reoccurrence of VF/pVT would improve safety during transport.

Summary

  1. CPR and defibrillation are the only treatments that will improve survival with VF/pVT.
  2. Consider either amiodarone or lidocaine for shock refractory VF/pVT.
  3. No antiarrhythmic will increase long-term survival or survival with good neurological outcome. They can increase short-term outcomes like ROSC or survival to hospital admission.
  4. Improved short-term survival with a witnessed arrest when the antiarrhythmic potentially could be administered sooner compared to unwitnessed arrest.
  5. Optimal sequence for ACLS interventions for VF/pVT with regards to timing of antiarrhythmics, a vasopressor, and defibrillation are unknown.

Reference

  • Panchal, A.R., Berg, K.M., Kudenchuk, P.J., Del Rios, M., Hirsch, K.G., Link, M.S., Kurz, M.C., Chan, P.S., Cabanas, J.G., Morley, P.T., Hazinski, M.F., & Donnino, M.W. (2018). 2018 American Heart Association focused update on advances cardiovascular life support use of antiarrhythmic drugs during and immediately after cardiac arrest. Circulation, 138. E740-e749. DOI: 10.1161/CIR.0000000000000613