Evaluation of the efficacy and tolerance of the antiarrhythmic agent transcainide (R 54718).

The antiarrhythmic efficacy of transcainide has been studied in 41 patients. It abolished ventricular arrhythmias in 10 out of 12 patients after i.v. administration and in 11 out of 14 after oral administration. It also reduced ventricular arrhythmias during recovery from exercise. The maximum intravenous dose prolonged the PR-interval by 43% and QRS-duration by 37%. Side-effects observed in 6 out of 41 patients included Mobitz Type I AV block, complete bundle branch block, hypotension and increased arrhythmia frequency. Transcainide is a promising new antiarrhythmic drug which should be used with caution in patients with conduction disorders and impaired cardiac function. Its value and safety in the chronic oral treatment of life-threatening arrhythmias remains to be established.