Comparison of right atrial and peripheral procainamide infusion levels in patients with spontaneous or induced atrial fibrillation

As part of a new effort to develop an implantable drug infusion/ pacing system to treat atrial fibrillation, this study examined the effects of rapid intracardiac procainamide infusion in humans with pacing-induced atrial fibrillation. Twenty patients with atrial fibrillation for >5 minutes during an EP study received 500mg of procainamide either via a peripheral venous infusion (n=5) or directly in the right atrium (n=15). Peak coronary sinus and femoral vein procainamide blood levels (mean ± SEM) during 10, 5, and 3.3 minute central infusions were 17.0 ± 4.1, 25.1 ± 4.5, 45.6 ± 5.1 and 11.3 ± 3.2, 17.1 ± 6.4, 18.7 ± 5.0, respectively. In contrast, peak coronary sinus and femoral procainamide levels following the 5 minute intravenous infusion were 17.7 ± 5.1 and 9.3 ± 2.1. Changes in QT, QTc, QRS, and RI intervals were similar at each infusion rate. Systolic blood pressures (BP) decreased more with higher procainamide infusion rates but similar when comparing intravenous versus central drug administration at the same rate. The mean ± SEM decreases in blood pressure with the 10, 5, and 3.3 min procainamide infusions were 12f5, 20f11, and 39f14, respectively. Conversion to sinus rhythm was not a primary endpoint given the often transient nature of acute atrial fibrillation in this setting. We conclude that significantly higher femoral vein and coronary sinus procainamide levels can be achieved by central rather than peripheral drug infusion. These data support that concept that rapid central infusion of anti-arrhythmic therapy can result in high intracardiac levels of antifibrillatory agents for the treatment of paroxysmal atrial fibrillation.