الفهرس 
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Abstract
ECG is a proper bedside tool used in the emergency department to make a rapid diagnosis of ACS, allowing physicians to select an appropriate therapy and to predict potential cardiovascular complications. Patients with STEMI are potential candidates for fibrinolysis or percutaneous coronary intervention.
QT dispersion (QTd) has been represented as one such marker of the automatic heart tone. Clinical significance in QTd is based on the knowledge that regional heterogeneity of the adjacent cardiac muscle tissue action potential can trigger and sustain ventricular arrhythmias, especially in vulnerable myocardium in ischemic heart disease (IHD).
Many clinical trials proved that primary PCI is better than thrombolytic. However, little, if any, was reported about the analysis of the QTd alterations and GLS in STEMI patients undergoing thrombolytic therapy versus Primary Percutaneous Coronary Intervention (PCI). Furthermore, to study the implementation of different baseline characteristics and risk factors that may affect the QTd and GLS in AMI patients after receiving the reperfusion treatment.
Our study included 100 patients (37 males / 63 females) who presented by STEMI from August 2018 to February 2020. We did Primary PCI to 55 patients, while 45 of them received thrombolytic therapy. Primary PCI was the preferred strategy of reperfusion if the time from STEMI diagnosis to wire crossing was less than 60 minutes (if the patient was presented in a PCI capable hospital) or less than 90 minutes (if the patient could be transferred to a PCI capable hospital). Otherwise, thrombolytic therapy was the preferred strategy. Any patient presented later than 120 minutes from the onset of chest pain were excluded from the study.
Primary PCI is superior to thrombolytic regarding global longitudinal strain results and QT dispersion reduction 48 hours after revascularization in STEMI patients. The study showed that patients who were managed by thrombolytic therapy had significantly higher QT dispersion after 48 hours of reperfusion (P-value≤0.001). QT dispersion reduction decreased significantly after revascularization in both groups (P-value<0.001), but the mean difference of decline was significantly higher in the primary PCI group. The percent of the QT dispersion reduction was significantly higher in patients managed by PCI (37.2%±5.7%) than in patients managed by thrombolytic therapy (14.1% ±6.9%) (P-value<0.001). These findings suggest that ischemia-induced Qtd and prolonged Qtc are important arrhythmogenic parameters responding to successful primary PCI and may be used as an indicator for successful primary PCI after 48 hours. (386) These results can be related to the higher TIMI 3 flow patency rate obtained by primary PCI.
The superiority of primary PCI over thrombolytic therapy in QT dispersion reduction and global longitudinal strain results was more evident in females than males. The primary PCI group showed that QT dispersion reduction was significantly higher in females than males (P-value<0.001), and the global longitudinal strain was significantly more negative value in females than males (P-value=0.012). Although, the thrombolytic group reveals no statistically significant differences between males and females regarding QT dispersion reduction and global longitudinal strain.
There was a significant moderate positive linear correlation between the patients’ age and the rate of QT dispersion reduction in the thrombolytic group (r=0.349 & p-value=0.020). There was a significant moderate positive linear correlation between the patients’ BMI and the Global Longitudinal strain in the thrombolytic group (r=0.367 & p-value=0.013) because obese patients exhibit the most LV structural remodeling and impaired myocardial function early after the infarction compared with normal and overweight patient groups.
QT dispersion reduction, whatever the revascularization strategy, is better in Non-smokers than smokers. The percent of QT dispersion reduction was significantly higher in non-smoker patients in both groups (P-value=0.003 & 0.010). However, Diabetes mellitus and hypertension (P-value>0.05) do not affect QT dispersion reduction either in primary PCI or thrombolytic.
Global Longitudinal strain results, whatever the revascularization strategy, are better in Non-smokers than smokers [GLS was significantly less negative in smoker patients in both groups (P-value=0.009 & 0.025)] & Non-diabetics than people with diabetes [GLS was significantly less negative in diabetic patients in both groups (P-value<0.001 & 0.023)]. For that reason, GLS could be an early marker of left ventricular dysfunction as well as evidence of diabetic cardiomyopathy. (394) However, hypertension does not affect Global Longitudinal strain results either in primary PCI or thrombolytic (P-value>0.05).
Global Longitudinal strain was significantly less negative in patients with dyslipidemia in the thrombolytic group only (P-value=0.028).
Global Longitudinal strain was significantly less negative in patients with a positive family history of CAD in the thrombolytic group (P-value=0.018)
QTd on admission and the percent of QTd reduction were significant predictors for the occurrence of VT irrelevant on the type of intervention at a cut off >152 msec. on admission (Sensitivity 85.71%, Specificity 97.85%, PPV 75%, NPV 98.9%) and cut off ≤7.7 % of QTd reduction 48 hours after the intervention (Sensitivity 85.71%, Specificity 94.62%, PPV 54.5%, NPV 98.9%)
QTd on admission and the percent of QTd reduction were significant predictors for the occurrence of VT on the thrombolytic group at a cut off >152 msec. on admission (Sensitivity 83.33%, Specificity 97.44%, PPV 83.3%, NPV 97.4%) and cut off ≤6.3 % of QTd reduction 48 hours after the thrombolytic therapy (Sensitivity 83.33%, Specificity 87.18%, PPV 50%, NPV 97.1%)
The positive impact of primary angioplasty in the recovery of myocardial function possibly extends beyond the benefits achieved by the establishment of epicardial coronary arterial flow. Ultimately leading to better outcomes due to better myocardial salvage and less fatal arrhythmias with primary PCI than fibrinolysis.
Primary angioplasty should remain the reperfusion strategy of choice in acute STEMI whenever feasible.