The effectiveness of antiarrhythmic agents on early-cycle premature ventricular complexes.

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Abstract
Patients (12) completed a double-blind, crossover antiarrhythmic drug trial in which 300 mg of quinidine, 500 mg of procainamide, 100 mg of phenytoin or placebo was given 4 times daily in subsequent weeks. Analysis of 24-h Holter tapes with a computerized analysis system (Argus/H) permitted accurate counting of premature ventricular complexes (PVC) subclassified according to coupling interval. No antiarrhythmic agent demonstrated a significant overall reduction in the number of PVC, but both quinidine and procainamide showed a statistically significant (P < 0.05) reduction of PVC with coupling intervals < 400 ms. This effect was noted both in isolated PVC (quinidine only) and in PVC that were part of a couplet or run (both drugs). Clinically important effects of procainamide and quinidine apparently can occur in the absence of an overall reduction in the number of PVC.