The Effect of Atenolol on QT Interval in Instrumented Beagle Dogs

In cardiology, the QT interval is a measurement of the heart’s electrical cycle between the start of the Q-wave and end of the T-wave in electrocardiogram (ECG). Assessment of the QT interval is of clinical importance because prolongation of repolarization may be associated with malignant ventricular arrhythmias and sudden cardiac death. Atenolol, a beta-blocker, is an effective anti-hypertensive agent that its protective effect may reduce the QT interval in some patients. However, the data of atenolol in animals or patients with long-QT syndrome are limited. The goal of this paper was to evaluate the effect of atenolol on QT interval in beagle dogs. Two experiments conducted by the Health and Environmental Sciences Institute were used for the evaluation. In two Latin-square studies, beagles were given varying levels of atenolol on separating dosing days and their ECGs were measured telemetrically. As QT interval is correlated with heart rate, we investigated the relationship between heart rate and QT interval using the vehicle control group animals. In addition to QTcF, QT interval corrected based on Fridericia’s formula, QTcP, which was based on the study population, and QTcI, which was derived from each individual animal, were evaluated. QTcF, QTcP, and QTcI were analyzed for each dose group at each time point compared to the vehicle. The analyses suggest that atenolol does not affect QT interval in beagle dogs.