A DOUBLE-BLIND CROSSOVER COMPARISON OF FLECAINIDE AND SLOW-RELEASE MEXILETINE IN THE TREATMENT OF STABLE PREMATURE VENTRICULAR COMPLEXES

In 24 patients with stable premature ventricular contractions (PVCs) greater-than-or-equal-to 100/h, Lown class greater-than-or-equal-to 2 the relative anti-arrhythmic efficacy of flecainide 150 mg twice daily and slow-release mexiletine 360 mg twice daily was evaluated in a double-blind placebo-controlled randomized crossover study. All the patients had normal ventricular function. Criteria of efficacy were: reduction greater-than-or-equal-to 70% of PVCs or reduction greater-than-or-equal-to 50% with abolition of Lown class > 2 arrhythmias or suppression of non-sustained ventricular tachycardias (nSVT). Twenty-two patients completed the study protocol. The placebo phases showed comparable results and no carry over effect. The criteria of efficacy were fulfilled in 20 of the 22 patients (91%) on flecainide and in 12 of the 22 (55%) on mexiletine. The absolute reductions of PVCs, couplets and nSVT obtained on flecainide and mexiletine, in comparison to the placebo, were statistically significant (p < 0.01 for flecainide, p < 0.05 for mexiletine). Flecainide was superior to mexiletine in overall PVC reduction (p < 0.05). In the 17 patients with couplets the reduction obtained with flecainide was superior to mexiletine (p < 0.05). Both drugs were highly effective on nSVT. At steady state, the mean plasma levels of both drugs were within the range of clinical efficacy. The drugs were well tolerated and no patient withdrew because of side-effects. It was concluded that at the dosages employed flecainide was superior to mexiletine in reducing premature ventricular contractions and in abolishing couplets. The efficacy of both drugs for non-sustained ventricular tachycardias was comparable. Both drugs were highly effective by comparison with the placebo.