Guidelines and heartlines: evaluating procainamide use at a large academic medical center

Abstract Procainamide is a Class IA antiarrhythmic with conduction-slowing and vasodilatory properties. Additionally, procainamide has a metabolite, n-acetyl procainamide (NAPA) which is also pharmacologically active, however it acts as a Class III antiarrhythmic. The American Heart Association designated procainamide as a "broad spectrum" antiarrhythmic to be used in hemodynamically stable patients with either atrial and ventricular arrhythmias (VA). In hemodynamically stable patients, several studies have shown the efficacy of procainamide to convert patients back to normal sinus rhythm when experiencing atrial dysrhythmias or ventricular dysrhythmias. Currently, there is limited published data on the safety and efficacy of procainamide in hemodynamically unstable patients or critically ill patients. Typically, loading doses of procainamide not to exceed a total dose of 1000 mg and continuous infusions ranges of 1-4 mg/min are used in our cardiac intensive care units (CICU). The purpose of this retrospective cohort study was to evaluate the effectiveness and tolerability of intravenous (IV) procainamide for the treatment of VA. This was a multi-center, retrospective cohort study of adult patients who received IV procainamide for the treatment of any arrhythmia or for the diagnosis of underlying cardiac channel abnormalities. The primary outcome was the effectiveness of procainamide in the treatment of VA, defined as escalations in number of shocks received, type of mechanical circulatory support (MCS), number of ablations received, and number of stellate ganglionic blocks received within 7 days. Secondary outcomes included the incidence of adverse events, including hypotension (defined as new vasopressor requirement, increase in vasopressor requirement, or SBP 90mmHg), electrocardiogram abnormalities, and hospital mortality. In addition, assessment of therapeutic drug monitoring (TDM) of procainamide and NAPA drug levels within 7 days were collected, if available. Procainamide was given as a loading dose primarily for atrial arrhythmia or electrophysiology studies, while VA were managed with a loading dose followed by a continuous infusion. Of the 43 patients in the VA subgroup, procainamide reduced the need for concomitant antiarrhythmic medications by a median of 1 antiarrhythmic drug (IQR 0-1) in 23 (53.5%) patients after 2 days of treatment. There were 10 patients in the VA subgroup that required therapy escalations, most commonly with additional MCS support. Out of the 12 patients that had TDM in the VA subgroup, only 1 patient had supratherapeutic procainamide and NAPA levels due to worsening renal function. Procainamide remains relevant in modern CICUs for patients failing conventional antiarrhythmics or those who are not hemodynamically stable for either arrhythmia suppression or bridge to advanced therapies, such as MCS or heart transplant.Total Daily Dose of Procainamide by Day