[Double-blind randomized placebo-controlled study of the effects of slow release and immediate release forms of propafenone in patients ventricular extrasystole symptoms].

This is a multicenter, randomized, double-blind, placebo-controlled, cross-over and double-dummy study aimed at testing the efficacy and tolerability of two slow-release propafenone (Pr SR) preparations and compare them with the effect of instant release propafenone (Pr IR). The study was performed in 83 patients with frequent (> 30 premature ventricular contractions/hour) and stable (< 35% variability in two 24-hour ECG monitoring periods) symptomatic premature ventricular contractions. Patients were preliminarily studied in wash-out from antiarrhythmic drugs. After a period of placebo administration, all patients underwent three consecutive periods during which they received Pr IR at the dosage of 150 mg x 3, Pr SR at the dosage of 225 mg x 2, Pr SR at the dosage of 325 mg x 2. The periods lasted 10-14 days each and the sequence was randomly assigned. Twenty-four-hour ECG monitoring periods were obtained at the end of the placebo as well as at the last day of each treatment period. Treatment efficacy was evaluated by intention to treat analysis in 80 patients and by protocol in 61. Treatment was considered efficacious when premature ventricular contraction reduction > or = 75%, couplet reduction > or = 90% and non sustained ventricular tachycardias were completely suppressed. Pr IR 150 mg x 3 was efficacious in 42% of patients, Pr SR 325 mg x 2 in 45.9% and Pr SR 225 mg x 2 in 32%. Tolerability was considered good in the majority of patients. These results show that among the different types studied, Pr SR 325 mg x 2 should be considered the treatment of choice for premature ventricular contractions.