Amiodarone vs Procainamide for Ventricular Tachycardia

The PROCAMIO Study(1)

This was a randomised (non-blinded) open labelled study. 62 haemodynamically stable patients with sustained, monomorphic, Ventricular Tachycardia(VT), were assigned to receive either:
(i) intravenous procainamide (single dose 10 mg/kg over 20 min) or
(ii) intravenous amiodarone (single dose 5 mg/kg over 20 min).

The study period was 40 min from infusion initiation (20 min for drug administration and 20 min following administration). There was an observation period of 24 h after the end of the study period.

The primary endpoint of the study was the incidence of major cardiac adverse events.
Secondary end-points were:
(i) the efficacy of both drugs in relation to the acute termination of the tachycardia episode and
(ii) the incidence of total adverse events during the observation period.

Overall the termination of VT occurred in 33 patients (53%). 67% of patients treated with procainamide reverted, compared to 38% of those treated with amiodarone.

As an adverse event, hypotension occurred in 8 patients on procainamide and 14 patients on amiodarone.

Comments

1 It’s interesting that the primary endpoint was not reversion. However it makes sense to see if a drug is tolerated. In one previous study(2) the rate of hypotension was higher with Procainamide.

2 Original anticipated numbers not reached in the study, so we need to be careful of the conclusions.

3 The dose of Procainamide used, was taken from a previous study that comparing procainamide with lignocaine(2). 10mg/kg was used. Usual dosage is 17 mg/kg given at a max rate of 50 mg/min, or 100 mg over 2 minutes every 5 minutes until conversion.  A higher dosage may be associated with more symptoms. However even at this lower dosage used in this study, the efficacy was there.

Previous Studies

A previous retrospective study comparing Amiodarone and Procainamide(3) looked at arrhythmia termination within 20 minutes of infusion. There were 90 patients in this study. The rates of VT termination were 25% (13/53) and 30% (9/30) for amiodarone and procainamide, respectively.
Ultimately, 35/66 amiodarone patients (53%, 95% CI=40 to 65%) and 13/31 procainamide patients (42%, 95% CI=25 to 61%) required electrical therapy for VT termination. Hypotension led to cessation of infusion or immediate direct current cardioversion (DCCV) in 4/66 amiodarone and 6/31 of procainamide, respectively.

In some countries it’s hard to get Procainamide. It certainly has been in Australian ED’s. However it is available and is used by electrophysiologists. We certainly now have this in my ED. Why do I like it? Not only can I use it for VT, but I can use it for AF with WPW, due to its actions on the accessory pathways.

References

1 Ortiz1, M et al.  Randomized comparison of intravenous procainamide vs. intravenous amiodarone for the acute treatment of tolerated wide QRS tachycardia: the PROCAMIO study. European Heart Journal June 28, 2016

2 Gorgels AP, et al.. Comparison of procainamide and lidocaine in terminating sustained monomorphic ventricular tachycardia. Am J Cardiol 1996;78:43–46.

3 Marill KA et al Amiodarone or procainamide for the termination of sustained stable ventricular tachycardia: an historical multicenter comparison. Acad Emerg Med 2010;17:297 – 306.