Procainamide for shockable rhythm cardiac arrest in the Resuscitation Outcome Consortium

Background: With recent negative studies of amiodarone and lidocaine for cardiac arrest, research into other antiarrhythmics is warranted. Literature on procainamide in cardiac arrest is limited. We evaluated procainamide for out-of-hospital cardiac arrests (OHCA) from the Resuscitation Outcomes Consortium (ROC). Methods: We included all ROC Epistry 3 OHCAs with an initial shockable rhythm that received an antiarrhythmic. We stratified cases by antiarrhythmic: procainamide, amiodarone, or lidocaine. The outcomes were prehospital return of spontaneous circulation (ROSC), ROSC in the ED, and survival to hospital discharge. We defined propensity scores based on possible confounders utilizing 1:1 propensity score matching to compare procainamide to amiodarone and lidocaine. We analyzed the matched data using logistic regression. We also used multivariable logistic regression to evaluate the association between antiarrhythmic and outcomes. Results: 3087 subjects met inclusion criteria; 51 patients received only procainamide, 1776 received amiodarone, and 1418 received lidocaine. On propensity score analysis and compared to procainamide, amiodarone had similar prehospital ROSC (OR 0.7, 95% CI 0.3–1.8), ED ROSC (OR 0.6, 95% CI 0.3–1.3), and survival (OR 1.0, 95% CI 0.3–3.1). Lidocaine also had a similar prehospital ROSC (OR 0.9, 95% CI 0.4–2.2), ED ROSC (OR 1.2, 95% CI 0.5–2.7), and survival (OR 1.4, 95% CI 0.5–4.0). However, using multivariable regression, amiodarone had lower prehospital ROSC than procainamide (aOR 0.3, 95% CI 0.1–0.6). Conclusions: While associated with increased prehospital ROSC when compared with amiodarone using multivariable regression, procainamide otherwise had similar prehospital ROSC, ED ROSC, and survival. The role of procainamide in OHCA remains unclear.