The influence of atenolol and propafenone on QT interval dispersion in patients 3 months after myocardial infarction.
The aim of the study was to determine changes in QTc dispersion and QTc interval during the administration of atenolol and propafenone.


METHODS
Eighty-five patients, 3 months after myocardial infarction, were randomized in 2 groups. The first group (n = 46) received atenolol 50 mg daily during 7 days and the second group (n = 39) propafenone 300 mg per os twice a day. QT interval was measured in 12 ECG leads before and after the treatment after 100% strip enlargement on a photocopy machine. For correction we used Bazett's formula. QTc dispersion was defined as the difference between the longest and the shortest QTc interval in 12 ECG leads.


RESULTS
QTc dispersion increased significantly with the severity of arrhythmia (< 50 premature ventricular complexes vs. ventricular tachycardia, 82.3 (18.1) vs. 110.0 (9.0) ms (p < 0.001)). QTc dispersion significantly decreases with the administration of atenolol (72.7 (14.8) vs. 63.6 (15.3)) (p < 0.001) as well as with propafenone (75.0 (17.7) vs. 63.2 (16.4)) (p < 0.001). QTc interval also decreases with atenolol (451 (28) vs. 431 (32)) (p < 0.01) while it does not change with propafenone administration (441 (26) vs. 444 (26)).


CONCLUSIONS
QTc dispersion is associated with ventricular tachycardia. Both atenolol and propafenone significantly decrease QTc dispersion. Atenolol also decreases QTc interval, while with propafenone it does not change.
Puljevic
D
D
Clinic for Cardiovascular Diseases, Medical University Zagreb, Croatia.
Smalcelj
A
A
Durakovic
Z
Z
Goldner
V
V
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D001262:Atenolol / Q000627:therapeutic use*; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy*; D011405:Propafenone / Q000627:therapeutic use*
D000319:Adrenergic beta-Antagonists; D001262:Atenolol; D011405:Propafenone