<b>QT Interval Dispersion</b>

Abstract

SUMMARYPrognostic assessment of unstable angina pectoris is a common clinical problem for physicians. Markers of myocardial cell injury, serial electrocardiographic findings and ST segment monitoring are mainly studied for prognosis.We investigated the relation between myocardial injury and the value of cardiac troponin T and QT interval dispersion in hospitalized unstable angina patients. This is a prospective study that includes adult patients admitted to an emergency department with Braunwald class IIIB unstable angina pectoris. Eighty-six patients were enrolled in the study (mean age of 57 ± 12 years, 63 males and 23 females). Cardiac troponin T was assayed and QT dispersion calculated from surface ECG. Fifty-eight patients with troponin T < 0.1 ng / ml and 28 patients with troponin T levels ≥ 0.1 formed group 1 and group 2, respectively.There were no significant differences in sex, age, history of coronary revascularization or ECG findings such as ST depression and T inversions between the two groups. The QT dispersion was significantly greater in patients with elevated cardiac troponin T levels (77 ± 18 msec vs 38 ± 13 msec; p < 0.014).Because QT interval dispersion exhibited an association with cardiac troponin T levels, it may be used as a non-invasive marker of ischemic injury in patients with unstable angina. (Jpn Heart J 2000; 41: 597-603) Key words: Unstable angina pectoris, QT dispersion, Troponin T IDENTIFICATION of patients with acute chest pain at high risk for cardiovascular complications is a common clinical problem for physicians. Surface ECG has been one of the most studied parameters for this purpose.1-4) QT interval on the surface electrocardiogram (ECG) is a measure of total time of ventricular depolarization and repolarization. Regional differences in ventricular repolarization are reflected as differences in QT intervals in leads corresponding to differents part of the myocardium. This heterogeneity is called QT interval dispersion.

The Association between QT Dispersion-QT Dispersion Ratio and the Severity-Extent of Coronary Artery Disease in Patients with Stable Coronary Artery Disease

“…QT dispersion and QT dispersion ratio, a non-invasive diagnostic tool in clinical practice, is not routinely used in our daily practice; however, it is associated with various CAD clinical forms. Several published studies have also emphasized using QT parameters as a non-invasive marker of CAD in patients with suspected CAD (29). We showed a significant association between QTd and QTdR and CAD extent and severity.…”

A predictive model to identify patients with suspected acute coronary syndromes at high risk of cardiac arrest or in-hospital mortality: An IMMEDIATE Trial sub-study

“…Previous investigators [10] have suggested a predictive role of QTc as a function of time since onset of symptoms suggestive of ACS, reflects myocardial injury and prolongation of QTc (and QT dispersion) [14] , [15] , potentially promoting ventricular arrhythmias and cardiac arrest. Although univariate analyses did not demonstrate significant predictive value of QTc or duration of symptoms, a composite variable of QTc with duration of chest pain since onset was created as described in the literature [10] .…”

“…We used both heart rate and systolic blood pressure to account for the hemodynamic state of the patient, including a composite variable found significant for predicting mortality from ACS in another study [14] . No improvement was noted in the model as measured by C statistic.…”