Evaluation of the anti-arrhythmic action of propafenone treatment and its influence on left ventricular function

Twelve patients (9 males, 3 females, mean age 59.2 +/- 7.0 years) with hyperkinetic ventricular arrhythmias were treated for 30 days with 150 mg propafenone three times daily; the daily dosage was raised to 900 mg in non responders (< 85% reduction of ectopic ventricular beats/h). A 24-hour ECGD and mono- and bidimensional echocardiography were carried out at baseline, after 30 days on 450 mg, 30 days on 900 mg propafenone, and one week after drug withdrawal. Propafenone treatment was found to reduce significantly ectopic ventricular beats, especially with the higher dosage (44.9% reduction under 450 mg; 88.8% reduction under 900 mg). At the lower dosage, 25% of patients responded, under the higher dosage 88.9%; the latter dosage also induced a significant reduction of Lown class. Propafenone treatment was also accompanied by a reduction of maximum and mean heart rate, and by a lengthened PR interval which was almost always within the normal range, without changes of QTc. The two months of propafenone treatment did not induce significant changes of cardiac volume or left ventricular function; on the contrary, at the end of the treatment period an increase, albeit not a significant one, of the ejection fraction and a shortening of the circumference inversely proportional to the reduction in ectopic ventricular beats could be noted. In conclusion, propafenone was found to have a valid antiarrhythmic effect, especially at the 900 mg/day dosage without interfering with left ventricular function which was even found to improve under chronic treatment, probably as a result of improved compliance thanks to the reduction of ventricular ectopic beats.