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Contributor: Aaron Lessen, MD Educational Pearls: How do amiodarone and lidocaine work on the heart? Amiodarone Blocks potassium channels (Class III effect). Also blocks sodium and calcium channels. Additional noncompetitive beta-blocker effects. Stabilizes cardiac tissue, slows heart rate, and suppresses both atrial and ventricular arrhythmias. Lidocaine Blocks fast sodium channels in ventricular tissue (Class Ib). Shortens the action potential in ventricular myocardium, especially in ischemic tissue. Suppresses abnormal automaticity in damaged/irritable myocardium. Which one should you pick for a patient in vtach/vfib cardiac arrest? The current guidelines recommend amiodarone for shock-refractory cases but this is based on randomized trials showing better arrhythmia termination and short-term outcomes, but not long-term survival benefits. Two recent studies suggest that lidocaine might actually be preferable. A 2023 paper published in Chest Performed a large retrospective cohort study for treating in-hospital VT/VF cardiac arrest. Among more than 14,000 patients, lidocaine was associated with higher rates of ROSC, 24-hour survival, survival to discharge, and favorable neurologic outcomes. These results held after adjusting for covariates and using propensity score methods. Overall, lidocaine outperformed amiodarone across all major clinical outcomes in this population. A 2025 paper published in Resuscitation Performed a target trial emulation in adults with out-of-hospital shockable cardiac arrest. After propensity score matching in more than 23,000 eligible cases, lidocaine was associated with higher odds of prehospital ROSC, fewer post-drug defibrillations, and greater survival to hospital discharge. These advantages were consistent across matched patient pairs. Dose for lidocaine is an initial 1-1.5 mg/kg IV bolus, followed by additional boluses of 0.5-0.75 mg/kg every 5-10 minutes up to a total of 3 mg/kg if needed. Dose for amiodarone is a 300 mg bolus followed by an additional 150 mg bolus if needed. References Al-Khatib SM, Stevenson WG, Ackerman MJ, Bryant WJ, Callans DJ, Curtis AB, Deal BJ, Dickfeld T, Field ME, Fonarow GC, Gillis AM, Granger CB, Hammill SC, Hlatky MA, Joglar JA, Kay GN, Matlock DD, Myerburg RJ, Page RL. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: Executive summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Heart Rhythm. 2018 Oct;15(10):e190-e252. doi: 10.1016/j.hrthm.2017.10.035. Epub 2017 Oct 30. Erratum in: Heart Rhythm. 2018 Nov;15(11):e278-e281. doi: 10.1016/j.hrthm.2018.09.026. PMID: 29097320. Smida T, Crowe R, Price BS, Scheidler J, Martin PS, Shukis M, Bardes J. A retrospective 'target trial emulation' comparing amiodarone and lidocaine for adult out-of-hospital cardiac arrest resuscitation. Resuscitation. 2025 Mar;208:110515. doi: 10.1016/j.resuscitation.2025.110515. Epub 2025 Jan 23. PMID: 39863130; PMCID: PMC11908894. 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. Summarized by Jeffrey Olson, MS4 | Edited by Jeffrey Olson and Jorge Chalit, OMS4 Donate: https://emergencymedicalminute.org/donate/