الفهرس 
Cardiac Electrical Activity and Surface ECGOnly 14 pages are availabe for public view
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Abstract
Acute myocardial infarction is a major health problem that results from coronary artery occlusion. It constitutes a major event and carries significant morbidity and mortality.
The mainstay treatment of such condition is the emergent re-opening and hence reperfusion of the jeopardized myocardium. This is carried out either pharmacologically through thrombolytic therapy or mechanically through percutaneous coronary intervention.
With the evolution of the definition of successful reperfusion, there is a need for simple, reliable as well as early method for detecting successful reperfusion.
The present study aimed at examining the relationship between dynamic T-wave changes at the time of reperfusion with myocardial salvage in patients with acute ST-segment elevation myocardial infarction.
The study included 33 patients presenting to Ain Shams university hospital with acute STEMI, who were eligible for reperfusion therapy whether by primary PCI or via thrombolytic therapy (streptokinase infusion).
All the patients had 12 lead ECG done before reperfusion (index ECG) and post reperfusion.
Several parameters were compared between the two ECGs done including:
I-T-wave morphology:
For the index ECG and the post-revascularization ECG, the T-wave morphology was categorized as:
1- Pure positive,
2- Pure negative,
3- Biphasic,
4- Isoelectric (Jacob et al., 2009).
II- T wave amplitude:
All T-wave amplitudes were categorized into 4 groups:
1- Negative (net amplitude, −∞ to < 0 mV),
2- Slightly positive (net amplitude, 0 to < 0.50 mV),
3- Moderately positive (net amplitude, ≥0.5 to < 1 mV), and
4- Highly positive (net amplitude, ≥1 mV) (Jacob et al., 2009).
III- Dynamic T-wave changes from index to post-revascularization ECG:
They were also divided into 4 groups:
1- negative change of more than 1 mV,
2- negative change between 0.5 and 1 mV,
3- negative change up to 0.5 mV, or
4- positive change (Jacob et al., 2009).
IV- T peak-Tend interval.
V- Macro T-wave alternans (TWA).
VI- ST segment elevation.
VII- ST segment resolution.
The success of reperfusion was evaluated by assessing the myocardial salvage by Tc99m sestamibi perfusion imaging.
Each patient had two myocardial perfusion SPECT images before and after reperfusion. Both images were used to assess the initial and final infarct sizes and hence calculating the salvage index.
The perfusion defects before and after reperfusion were evaluated through the SPECT images using the scoring system for the standard 17 segment representing the left ventricle.
A summed score was calculated before and after reperfusion , through which a salvage index was calculated.
Comparing the salvage index with the previously mentioned ECG parameters showed that:
The more negative dynamic T wave changes from the index ECG, the better the reperfusion as assessed by the myocardial salvage index, percentage of ST segment resolution, ejection fraction (P<0.01 ) and final size of infarction (P=0.05).
In the post- revascularization ECG, the final T-wave amplitude was positively associated with final infarct size (P=0.04), and inversely associated with the salvage index, and with ST resolution (P<0.01), left ventricular ejection fraction (P=0.05).
A net decrease in T-wave amplitude after reperfusion therapy was associated with faster micro-vascular reperfusion as evaluated by myocardial salvage.
It also showed that T peak-Tend interval decreased significantly post procedure, and that this reduction is significantly correlated with successful reperfusion as shown by the higher the myocardial salvage (P<0.01), the smaller the final size of infarction (P=0.02), the higher ejection fraction (P=0.2), and the higher the percentage of ST segment resolution (P<0.01).
In patients with STEMI the more negative dynamic T wave changes and T peak to Tend, and the more negative the final T wave amplitude the better the outcome.