Discordant prolongation of the refractory period and repolarization time by a class III agent, E4031, in the healing phase of myocardial infarction

Seiji Takatsuki, Hideo Mitamura, Koichiro Sueyoshi, Hideaki Kanki, Izumi Furuno, Satoshi Ogawa

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Susceptibility to reentrant tachyarrhythmias and the antiarrhythmic efficacy of class III agents are related more to the duration of the refractory period (ERP) than to the repolarization time (RT). We measured both ERP and RT in a canine model of healing myocardial infarction, and evaluated the effect of a class III agent (E4031) on these parameters and on the inducibility of ventricular tachyarrhythmias. ERP and RT on the unipolar electrogram were measured at several cycle lengths in the normal (NZ) and infarct zones (IZ), respectively, in 10 canine myocardial infarction models and extrastimulation was used to induce ventricular arrhythmias. Measurements were repeated after E4031 administration. At baseline, both ERP and RT were significantly longer in IZ than in NZ with ERP/RT ratio also higher in IZ. This ratio tended to increase at longer cycle lengths. E4031 increased ERP and RT both in NZ and IZ at all cycle lengths, but increased the ERP/RT ratio predominantly in IZ. E4031 prevented induction of sustained VT or VF, which was inducible in 3 out of 10 dogs at baseline, although it facilitated induction of VF in 1 dog wth no baseline arrhythmia. By increasing the ERP/RT ratio, class III drugs may shorten the relative refractory period in IZ at the expense of a greater ERP difference created between NZ and IZ.

Original languageEnglish
Pages (from-to)687-697
Number of pages11
JournalJapanese Heart Journal
Volume39
Issue number5
DOIs
Publication statusPublished - 1998 Sep

Keywords

  • Canine
  • Class III antiarrhythmic agent
  • Myocardial infarction
  • Refractory period
  • Repolarization
  • Ventricular arrhythmia

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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