Amiodarone 150 mg IV over 10 minutes and procainamide IV 20-50 mg/min (up to 17 mg/kg) are two antiarrhythmic medications recommended in the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care for stable wide QRS complex tachycardia. [1]

What they did:

Multi-center, prospective, randomized, open-label trial comparing the incidence of major cardiac events in the acute treatment of hemodynamically stable patients with wide QRS monomorphic tachycardia (presumed to be VT) using amiodarone 5 mg/kg IV infused over 20 minutes versus procainamide 10 mg/kg IV infused over 20 minutes. [2] The study period was 40 minutes, starting from the beginning of the infusion.

What they found:

• Analysis included 62 (n=33 procainamide, n=29 amiodarone) patients from 16 hospitals
• Fewer patients treated with procainamide experienced major cardiac events during the study period compared to those who received amiodarone (9% vs 41%; OR =0.1, 95% CI 0.03-0.6; P=0.006). The most frequent adverse cardiac event was severe hypotension requiring electrical cardioversion.
• Termination of VT occurred more frequently in patients treated with procainamide (67% vs 38%; OR =3.3, 95% CI 1.2-9.3; P=0.026).

Application to clinical practice:

• Medication doses and patient weights are not reported in the results. A comparison of the doses used in the PROCAMIO study to those recommended in the AHA guidelines for a 70 kg and 100 kg patient are as follows:
  • Procainamide:
    • 70 kg patient would receive procainamide 35 mg/min for 20 minutes. This is in the middle of the dose range recommended by the AHA.
    • 100 kg patient would receive procainamide 50 mg/min for 20 minutes. This is the upper limit of the dose range recommended by the AHA.
  • Amiodarone:
    • 70 kg patient would receive amiodarone 350 mg over 20 minutes. This is approximately equal to administering 2 doses of 150 mg at the infusion rate recommended in the AHA guidelines.
    • 100 kg patient would receive amiodarone 500 mg over 20 minutes. This is approximately equal to administering 3 doses of 150 mg at an infusion rate over 1.5 times higher than that recommended in the AHA guidelines.

• The study size was small, and depending on patient weights, it is possible that amiodarone dosing was more aggressive compared to doses commonly used in the US. However, the results suggest that procainamide could offer improved safety and efficacy over amiodarone for stable wide QRS tachycardia.

References

1. Neumar RW, Otto CW, Link MS, et al. Part 8: adult advanced cardiovascular life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2010;122(Suppl. 3): S729-S767.
2. Ortiz M, Martin A, Arribas F, et al. Randomized comparison of intravenous procainamide vs. intravenous amiodarone for the acute treatment of tolerated wide QRS tachycardia: the PROCAMIO study. Eur Hearrt J. 2016 Jun 28. Epub ahead of print. [PMID 27354046]

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