PMID: 7536244Apr 1, 1995Paper

The discordant influences of infarct healing on the electrophysiologic effects of procainamide and N-acetylprocainamide

The Journal of Pharmacology and Experimental Therapeutics
S D NelsonJ Meimer

Abstract

Ischemic zone refractoriness and conduction delay respond differently to infarct healing and, hypothetically, may exert discordant influences on the electrophysiologic action of different classes of antiarrhythmic drugs. This study evaluated the influence of infarct healing on the electrophysiologic effects of procainamide (PA) and N-acetylprocainamide (NAPA) in a sedated, closed-chest canine model with a healing anterior wall myocardial infarction, indwelling myocardial electrodes and inducible sustained ventricular tachyarrhythmias (VT). Infarct zone refractory periods, conduction times and the inducibility of VT were tested at base line and during infusion of PA or NAPA in a crossover study design at 1, 4 and 8 weeks of infarct healing. Data were presented as the percent magnitude of change from base line induced by drug. The magnitude of change during PA infusion in infarct zone refractory periods, but not conduction times, decreased during infarct healing (P < .001). The magnitude of change in refractory period and conduction time during NAPA was not significantly altered by the stage of myocardial infarction healing. At week 1, PA prevented inducible VT in 9 of 14 animals vs. 3 of 15 during NAPA infusion (P < .05). At wee...Continue Reading

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