الفهرس 
QT interval and QTcOnly 14 pages are availabe for public view
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Abstract
QTc and QTd are simple and easy predictors of cardiac electrical activity in many heart diseases. Both of them have special concern in cases of acute myocardial infarction.
The aim of the study was to detect the correlation between both (QTc and QTd) and left ventricular systolic function.
This prospective study enrolled 90 patients who were presented to our CCU with the first attack of acute ST elevation MI during the period from December 2006 till July 2007.And twenty persons were taken as a control group.
All patients were subjected to history taking, physical examination and laboratory investigations to rule out any other medical problems and to exclude medical conditions that affect measurements of QTc and QT dispersion.
All patients were managed by the most appropriate means of treating acute myocardial infarction whether primary PCI, thrombolysis or neither of them in certain cases.
Serial ECGs were done and the ECG of the 4th day was taken between10am and 4pm. Measurements of QTc were done manually then corrected using Bazett formula.QT dispersions were measured manually by determining the difference between the longest and the shortest QT interval in the surface ECG.
Echocardiographic examinations were done with special concern to regional wall motion followed by mathematical determination of wall motion score index as an indicator of global left ventricular systolic function. All data were collected in the master sheet and correlations were done among values of QTc, QTd and WMSI to detect presence of an associations between ECG obtained data (QTc and QTd) and echocardiography obtained data (WMSI).
Type of reperfusion therapy and site of infarction were involved in the statistical analysis.
In the control group, QTc had a mean value =442.024. +47ms, QTd had a mean value of 39.91+0.55ms, while WMSI was1 which were within normal range.
The results showed that there were no relation among risk factors and the values of QTc, QTd and WMSI.
A significant difference was noticed in values of WMSI in patients of anterior wall MI and inferior MI .Mean value of WMSI in anterior wall MI was1.5+0.3, while the same value in inferior wall MI was 1.2+0.1.
QTc was significantly prolonged in patients who were not managed with either thrombolytic therapy or primary PCI with a mean value of 463.9+13.7.
Significant differences were recorded in values of QTd in patients managed by thrombolytic therapy or primary PCI on one hand and patients who were not managed by either type on the other hand. QTd was significantly prolonged with a mean value of 54.8+13.2 in cases which did not receive thrombolytic therapy or primary PCI.
WMSI was significantly prolonged in patients who were not managed by thrombolytic therapy or primary PCI with a mean value of 1.84+0.2. In contrast, WMSI in cases managed by thrombolytic therapy or primary PCI had a mean value of 1.4+0.2 and 1.3+0.2 respectively.
There were significant positive correlations between both (QTc and QTd) with WMSI where r- value was 0.359 as a correlation between QTc and WMSI and 0.496 as a correlation between QTd and WMSI. P-value for both was <o.oo1.
The study found that there was a significant correlation between values of QTc and wall motion score index as a predictor of left ventricular systolic function following acute MI. The more preserved LV systolic function the more near QTc around normal value (mean QTc =444ms). The same was true concerning QT dispersion, where its values were within normal range (mean QTd was less than 40 ms) in cases of preserved LV systolic function and QT dispersion was prolonged if LV systolic function deteriorated following acute MI.
The study showed that measuring of QTc and QTd could be a simple, feasible and non-invasive predictor of the success of the reperfusion therapy, where their values were prolonged in cases of more injured myocardium following acute MI .This was obvious in cases where reperfusion therapy was not given.