Objective To observe the therapeutic effect of Wushen Fumai Decoction for premature ventricular contractions after viral myocarditis and its influence on QT interval dispersion.Methods One hundred cases of chronic viral myocarditis with frequent premature ventricular contractions were randomized into the observation group and the control group

with 50 in each.The control group was given conventional therapy and 150mg of propafenone tablets

or 100mg when it was into effect

three times daily.The observation group was given conventional therapy and Wushen Fumai Decoction one dosage daily.The treatment course lasted for 30 days.The number of premature ventricular contractions and the change of QTd and QTcd were observed with electrocardiogram（ECG） and 24-hour ambulatory ECG before and after treatment.Results There were 27 cases of excellence

15 cases of validity and 8 cases of invalidity in the observation group

with a total effective rate of 84.0%.There were 29 cases of excellence

16 cases of validity and 5 cases of invalidity in the control group

with a total effective rate of 90.0%.There was no significant difference in the total effective rate between groups（P>0.05）.There was no significant difference in QTd

QTcd and the frequency of premature ventricular contractions between groups before treatment（P>0.05）.After treatment

QTd and QTcd significantly decreased in the observation group

with statistical difference between groups and in group（P<0.05 or P<0.01）.The frequency of premature ventricular contractions decreased significantly in both groups（P<0.01）

especially in the control group（P<0.05）.However

the incidence of adverse reactions in the observation group was significantly lower than that in the control group（P>0.05）.Conclusion Wushen Fumai Decoction is effective for frequent premature ventricular contractions after viral myocarditis

with less therapeutic effect than propafenone.However

Wushen Fumai Decoction could shorten QTd and QTcd without obvious side effects as compared with propafenone.