Effects of Metoprolol on QT Dispersion and Heart Rate Variability in Patients with Coronary Artery Disease

Objective:To investigate the Effects of Metoprolol on QTDispersion(QTd)and Heart Rate Variability(HRV)in Patientswith Coronary Artery Disease(CAD).Methods:The changes of QTd and HRV were investigatedbefore and after administrating Metoprolol(93.75±22.8mg/d)for two weeks in the 24 patients with CAD.Results:Compared with healthy adults,the QTd,QTcd andQTmax were significantly higher(p<0.05)in the patients withCAD,and the QTmin lengthened and the QTd shortened whentaking Valsalva s respiration,the SDNNindex,rMSSD,PNN50and HF increased significantly(p<0.01),and LF/HF ratiodecreased,but the SDNN,SDANN and LF did not change afteradministrating Metoprolol.In addition,the QTmin shortened,the QTd,QTcd lengthened significantly(p<0.05),but the QTmaxhad no significant change after administratingMetoprolol(p>0.05).Condusions:The results suggest that the sympathetic nervecould regulate the repolarization speed of the normalventricular myocardium,and change the QTd in the patientswith CAD,Metoprolol relieve not only angina pectoris byincreasing efficiently the blood supply,and decreasing theoxygen demand of the myocardium,but also shorten markedlythe QTd.