[Long-term treatment with the new antiarrhythmic drug propafenone in correlation to plasma levels (author's transl)].

The results of long term oral therapy of cardiac arrhythmias in 43 patients successfully treated with propafenone are reported. The patients were treated for periods ranging between 1 month and 34 months with a mean of 13.4 months. The administered dose varied between 150 mg tds and 300 mg qds with an average daily dose of between 600 and 750 mg. The doses were decided on a body-weight basis with range of 6 to 17 mg/kg and an average of 12 mg/kg. Altogether 30 patients were successfully treated over a long period, sometimes in combination with other antiarrhythmic agents, particularly beta-blockers. 2 patients did not appear after some first controls. In 7 patients the drug was not effective, even when used in combination with others. 4 patients stopped the treatment due to side-effects. Further 18 patients complained temporarily of gastrointestinal and cerebral side-effects. Some Ecg changes were noted, particularly A-V conduction delays and spreading of the QRS-complex. We suggest that the clinically most important parameters for monitoring an antiarrhythmic regimen of propafenone are the patients's own history and Ecg-examination noting the PQ interval and particularly the width of the QRS-complex and long-term monitoring.