Recommended Citation: Bernstein V. The Cheese - Review of Antiarrhythmics in Shockable Rhythm Cardiac Arrest[Internet]. Cook County Emergency Medicine Residency;Available from: https://cookcountyem.com/blog/2023/11/15/the-cheese-review-of-antiarrhythmics-in-shockable-rhythm-cardiac-arrest
The scene: After a year of seemingly endless medium acuity overnight shifts, you’re finally ready to take on all the excitement and responsibility of resus. On a busy Tuesday evening, a witnessed arrest from the waiting room rolls into Resus 2 with CPR in progress, and your attending announces to the room that YOU will be leading the code. The monitor shows a wide complex tachycardia, and the patient still has no pulse. After three rounds of CPR, the nurse asks you if you want to give amiodarone or lidocaine. Well, do you?
This week’s cheese post will review recent literature that examines the role of antiarrhythmic medications in shockable cardiac arrest.
Does amiodarone or lidocaine improve survival or neurologic outcomes in out-of-hospital cardiac arrest with VF/VT?
In the ALPS study, a large prospective multi-site double-blinded prehospital control trial published in NEJM in 2016, patients with out-of-hospital arrest (OHCA) whose initial rhythm was either VF or pulseless VT were randomized to receive either amiodarone, lidocaine, or placebo. The authors examined survival to hospital discharge and favorable neurologic outcomes as their primary and secondary outcomes. They found no statistically significant difference in survival to hospital discharge or favorable neurologic outcomes. Furthermore, there was no significant difference between amiodarone or lidocaine for either outcome. These data challenge the supposed benefit of antiarrhythmics for shock-refractory VF/VT OHCA [1]. However, there was a significant difference in the number of shocks required to achieve ROSC in the active drug compared to placebo, suggesting a role of amiodarone/lidocaine in terminating deadly arrhythmias. Importantly, patients were more likely to survive to hospital admission after receipt of amiodarone or lidocaine than after receipt of placebo.
Answer: Although amiodarone or lidocaine did not show a clear benefit for OHCA patients with refractory shockable rhythms in terms of survival to discharge or neurologic outcomes, it did result in higher rates of survival to admission, which is helpful for the EM physician.
Does timing of antiarrhythmic medication matter in OHCA presenting with VF/VT?
In 2022, a post-hoc analysis of the same data from the ALPS trial was published in Academic Emergency Medicine by Lupton et. al. that asked if timing of drug administration affected survival to discharge or neurologic outcome. They found that amiodarone given ≤ 8 minutes after arrest had improved survival to admission, survival to discharge and neurologic outcomes compared to placebo, which was not seen with early lidocaine, late lidocaine or late amiodarone [2].
According to ACLS, amiodarone or lidocaine can be administered after 3 shocks. With the results from the post-hoc analysis, the data suggests that timely administration can make an important impact on patient outcomes. Notably, these benefits seem to disappear when the medication is administered via the IO route, although more research regarding route of administration is needed.
Answer: Consider early (timely) administration of amiodarone via IV in patients with OHCA presenting with initial shockable rhythms.
Ok, but what about for patients with shockable *in-hospital* arrest?
While these most recent studies favor amiodarone for out of hospital arrests, Holmberg et. al asked the same question for in-hospital arrests. In their observational study published in Chest in 2020, a total of 14,630 patients with in-hospital VF or VT arrest received either amiodarone or lidocaine. In comparison to the post-hoc analysis from the ALPS trial, this study found that lidocaine (and not amiodarone) was associated with statistically significantly higher rates of ROSC, 24 hour survival, survival to hospital discharge, and favorable neurologic outcome. There were some limitations with this study, given that it was observational rather than prospective, so take the results with a grain of salt. However, it does suggest a role for lidocaine in VF/VT arrest in the hospital [3].
Answer: Consider giving lidocaine during in hospital cardiac arrests with VF/VT.
Takeaways:
Consider giving timely amiodarone for out-of-hospital VF/VT arrest
Remember that lidocaine can also be used for VF/VT arrest
Authored by Vladimir Bernstein, MD
References:
Kudenchuk PJ, Wittwer L, Vaillancourt C, Leroux B, Morrison LJ, Nichol G, Rea T, Daya M, & Brown, S. P. (2016). Amiodarone, lidocaine, or placebo in out-of-hospital cardiac arrest. NEJM, 375(8):801–803. https://doi.org/10.1056/nejmc1608041
Lupton JR, Neth MR, Sahni R, Jui J, Wittwer L, Newgard CD, Daya MR. Survival by time-to-administration of amiodarone, lidocaine, or placebo in shock-refractory out-of-hospital cardiac arrest. Acad Emerg Med. 2023 Sep;30(9):906-917. doi: 10.1111/acem.14716. Epub 2023 Apr 5. PMID: 36869657.
Wagner D, Kronick SL, Nawer H, Cranford JA, Bradley SM, Neumar RW. Comparative Effectiveness of Amiodarone and Lidocaine for the Treatment of In-Hospital Cardiac Arrest. Chest. 2023 May;163(5):1109-1119. doi: 10.1016/j.chest.2022.10.024. Epub 2022 Nov 2. PMID: 36332663.