الفهرس 
CURRENT PRACTICE IN PRIMARY PERCUTANEOUS CORONARY INTERVENTIONOnly 14 pages are availabe for public view
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Abstract
T
he management of acute ST elevation myocardial infarction is still under the umbrella of research duo to the plenty of areas that are waiting for answers. Proper management and right decisions should be based on solid evidence derived from clinical trials.
MI is defined in pathology as myocardial cell death due to prolonged ischemia. After the onset of myocardial ischemia, histological cell death is not immediate, but takes a period of time to develop as little as 20 min, or less in some animal models. It takes several hours before myocardial necrosis can be identified by macroscopic or microscopic post-mortem examination. Complete necrosis of myocardial cells at risk requires at least 2-4 h, or longer, depending on the presence of collateral circulation to the ischemic zone, persistent or intermittent coronary arterial occlusion, the sensitivity of the myocytes to ischemia, pre-conditioning, and individual demand for oxygen and nutrients. The entire process leading to a healed infarction usually takes at least 5–6 weeks and reperfusion may alter the macroscopic and microscopic appearance(1). Myocardial injury is detected when blood levels of sensitive and specific biomarkers such as MB fraction of creatine kinase (CKMB) are increased.(2) Cardiac troponin I and T are components of the contractile apparatus of myocardial cells and are expressed almost exclusively in the heart. And Regardless of the pathobiology, myocardial necrosis due to myocardial ischemia is designated as MI.
During performing primary PCI, moderate to high thrombi may be found occluding the culprit artery partially or totally. Thrombus grading scales are essential tools used for qualification and quantification of the thrombus burden. They provide a platform for clinical assessment and subsequently affect the management decisions prior to and during interventions. The widely used TIMI thrombus grading scale was originally created by the TIMI study group investigators. TIMI classification relies on the angiographic assessment of the presence of thrombus and its relative size, utilizing a simple score ranging from grade 0 (no thrombus), to grade 5 (very large thrombus content that completely occludes vessel flow. (2)
Up till now, there is no definitive guidelines to follow in the cases of acute STEMI with moderate to high thrombus burden. So, the optimal management of a large intracoronary thrombus in patients with acute coronary syndromes and with an urgent need of revascularization is still unclear.
To investigate whether deferring the percutaneous coronary intervention in patients presented with STEMI with moderate to high thrombus burden after a course of intensive dual anti-platelet and IV Glycoprotein IIb/IIIa receptor antagonists (Tirofiban 25 mcg/kg bolus and 0.15 mcg/kg/min maintainance infusion or Eptifibatide 180 mcg/kg bolus and 0.5 mcg/kg/min) for 24-48 hours improves the outcomes compared with immediate PCI.
Patients:
Based on the following assumptions to calculate the sample size:
1. Alpha error = 0.0500 (two sided).
2. Power of the study = 0.8000
3. Percentage of distal embolization in PCI = 33%
4. Percentage of distal embolization with antithrombotic = 9%
The program that is used for sample size calculation is STATA 10.
It was an observational, retropective, nonrandomized case control study of 100 patients divided into 2 groups, 50 in each group. It will include the patients presented with acute ST elevation myocardial infarction with moderate to high thrombus burden. The first group included patients who underwent coronary angiography with immediate PCI. While the second group included the patients who were deferred for a second look with a trial of PCI after 24-48h hours of being treated with dual anti-platelet and Glycoprotein IIb/IIIa receptor antagonists (tirofiban (Aggrastat), or eptifibatide (Integrilin)). All patients had a pre-discharge echo for assessment and followed up 4 weeks after discharge for MACE.
Inclusion Criteria
1. Patients of both genders.
2. Age between 18 – 75 years of age.
3. Patients with acute STEMI eligible for primary PCI with moderate to high thrombus burden (grade 2 to 5 according to the TIMI thrombus scale).
The TIMI thrombus scale:
1. Grade 0: no angiographic evidence of thrombus.
2. Grade 1: angiographic features suggestive of thrombus:
A. Decreased contrast density
B. Haziness of contrast
C. Irregular lesion contour
D. A smooth convex meniscus at the site of a total occlusion
3. Grade 2: definite thrombus present in multiple angiographic projections:
Marked irregular lesion contour with a significant filling defect – the thrombus’ greatest dimension is <1/2 vessel diameter.
4. Grade 3: definite thrombus appears in multiple angiographic views. Greatest dimension from >1/2 to <2 vessel diameters.
5. Grade 4: definite large size thrombus present. Greatest dimension >2 vessel diameters
6. Grade 5: definite complete thrombotic occlusion of a vessel. A convex margin that stains with contrast, persisting for several cardiac cycles
Exclusion Criteria
1. Patients below 18 years or above 75 years of age.
2. Patients with acute STEMI with hemodynamic instability.
Methods:
All patients underwent the following:
History.
Examination.
12 lead Electrocardiogram (ECG).
Echocardiography.
Laboratory investigations.
Percutaneous Coronary Intervention.
Pre-coronary angiography.
During the procedure.
Follow up.
All patients who underwent immediate or delayed intervention were followed up for in-hospital morbidity and mortality with pre-discharge echo then after 1 month for MACE including:
Statistics
All the results were subjected to adequate statistical analysis and will be discussed.
Results
Deferring PCI in patients with STEMI and moderate to high thrombus burden, did not affect neither the TIMI flow at the end of the procedure nor the inhospital morbidity or mortality. After 4 weeks, MACE was similar in the deferral and immediate PCI groups. However, deferral carries and advantage of reducing the need for stenting. Thrombus aspiration may enhance the flow in the culprit artery and reduce the need for PCI.