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Prolongation of ventricular refractoriness by class Ia antiarrhythmic drugs in the prevention of ventricular tachycardia induction.
- Source :
-
American heart journal [Am Heart J] 1990 Oct; Vol. 120 (4), pp. 855-63. - Publication Year :
- 1990
-
Abstract
- The effects of class la antiarrhythmic drugs (procainamide, quinidine) on the right ventricular effective refractory period (VERP) and intraventricular conduction time were assessed during serial invasive electrophysiologic studies for sustained monomorphic ventricular tachycardia (VT). In 47 patients with remote myocardial infarction, sustained VT was inducible by up to two extrastimuli after the basic drive at one of two basic cycle lengths at the right ventricular apex. With oral drug administration, sustained VT was no longer inducible (group I) in 27 patients but remained inducible (group II) in 20 with the same protocol. Class la drugs prolonged the VERP in both groups, but there was greater lengthening when drugs were effective (e.g., +32 +/- 14 msec in group I vs +12 +/- 19 msec in group II; p less than 0.005, basic cycle length 600 to 700 msec). Prolongation of the VERP by greater than 30 msec had an 88% positive predictive value for prevention of sustained VT induction. In all except one patient in group I, drugs prolonged the VERP such that the coupling intervals that had resulted in sustained VT induction under control conditions were no longer attainable. In contrast, conduction time through the ventricle (surface QRS duration) in sinus rhythm and during right ventricular pacing was prolonged similarly regardless of efficacy (e.g., +33 +/- 21 msec vs +27 +/- 27 msec at a cycle length of 400 msec). The presence of similar plasma levels of drug did not imply equivalent prolongation of the VERP in the two groups. These results suggest that greater prolongation of the VERP by oral procainamide or quinidine correlates with drug efficacy against VT induction and is a better predictor of drug effect than achievement of a "therapeutic plasma level."
- Subjects :
- Adult
Aged
Aged, 80 and over
Anti-Arrhythmia Agents therapeutic use
Electrocardiography
Electrophysiology
Female
Humans
Male
Middle Aged
Procainamide pharmacology
Procainamide therapeutic use
Quinidine pharmacology
Quinidine therapeutic use
Anti-Arrhythmia Agents pharmacology
Tachycardia drug therapy
Ventricular Function drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 0002-8703
- Volume :
- 120
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- American heart journal
- Publication Type :
- Academic Journal
- Accession number :
- 2220538
- Full Text :
- https://doi.org/10.1016/0002-8703(90)90201-8