Contribution of Corrected QT Dispersion (QTcd) to Dobutamine Stress Echocardiography in Diagnosing Critical Coronary Artery Stenosis

The diagnosis of ischemic heart disease. QT dispersion defined as the difference between the longest and the shorthest QT interval on 12-lead electrocardiogram is a parameter depicting the heterogeneity of the ventricular repolarization. In this study, the contribution of QTcd during DSE to the specificity and sensitivity of the test in diagnosing ischemic heart disease was assessed. Thirty consecutive patients (22 male, 8 female; mean age 54±6 yrs) who were performed coronary angiography were taken into the study. After coronary angiography within one month, DSE was performed. In angiography by using visual methods, 18 patients with 60% stenosis and upper values were accepted as the study group while twelve patients with stenosis below 40% were accepted as the controls. QTcd on 12- lead electrocardiograms both before and just after DSE were measured. In the patient group, QTcd significantly increased from 51±8 msec to 60± 12 msec during dobutamin infusion (p=0.023), while it slightly decreased from 49±6 msec to 48±6 msec in the control group (p=0.471). The sensitivity and specificity of QTcd alone in depicting critical coronary artery stenosis were 56% and 58%; they were found 50% and 92% together with dobutamine stress echocardiography, respectively. In conclusion, measuring QTcd during DSE increases the accuracy of the test. This easily applicable method is thought to be helpful as an adjunct to DSE.