The Clinical Effect of Aprindine on Ventricular Extrasystole: A Comparison Study of Mexiletine by the Cross-over Method.

Purpose: A comparison study was Preformed for the clinical effects of aprindine (AP) on ventricular extrasystole in the same patient, using mexiletine (MX) as a control, by a cross-over method that used the envelope method.Method: Twenty-two patients from nine facilities with ventricular extrasystole of 5, 000/day or more were administered AP 40mg/day and MX 300mg/day.Prior to treatment and at the completion of each treatment, recordings of DCG, electrocardiogram at rest, and measurements of blood concentration were carried out.Results: A reduction rate of 50% or more in the total number of extrasystoles was observed in 12 patients (54%) administered AP, in 11 administered MX (50%), and although a Lown classification of IV or higher was observed in 16 patients, it improved to III or less in eight AP patients and in seven MX patients. In an analysis by the Lerenz plot method, the coupling interval was prolonged significantly by the administration of AP. The PQ interval and QRS width also were prolonged significantly by the administration of AP.Conclusion: AP was considered to be a drug that strongly suppresses conducting systems of the heart, especially atrial and intraventricular conduction.