Long-term antiarrhythmic therapy with flecainide.

The antiarrhythmic efficacy and safety of oral flecainide were assessed during a controlled 2-week and a subsequent 48-week long-term trial. Fifteen patients with frequent (more than 30 per hour) and complex ventricular arrhythmias (Lown grade IVA or IVB) who had been resistant or intolerant to 2 or more antiarrhythmic agents, were included in the study. Antiarrhythmic efficacy was controlled by 24-hour Holter monitoring at 2, 12, 24 and 48 weeks. The administration of 100 to 200 mg flecainide twice daily resulted in more than 90% suppression of VPCs and of complex ventricular arrhythmias in 14 of 15 patients. The minimum effective therapeutic dose could be titrated in 9 of 14 patients to 100 mg twice daily, in 3 of 14 patients to 150 mg twice daily and in 2 of 14 patients to 200 mg twice daily. During this therapy and a mean plasma concentration of 886 +/- 103 ng/ml, PQ and QRS duration, as well as QTc time and JTc interval were not significantly changed. Side effects (gastrointestinal complaints, nausea, obstipation, dizziness, visual disturbances, headache and impaired potency) were seen in 5 of 14 patients after 12 weeks, in 3 of 4 patients after 24 weeks and in only 2 of 14 patients after 48 weeks. Side effects were described as mild and tolerable and did not limit flecainide therapy except in 1 patient, who had discontinued therapy with flecainide after 3 days because of intense gastrointestinal symptoms. In conclusion, flecainide is highly effective and well tolerated in the long-term treatment of serious ventricular arrhythmias.