Follow up of Clinical Outcome of Deferred vs Immediate Stenting in High Thrombus Stemi Patients

Short Term Clinical and Major Cardiovascular Adverse Events of Deferred Versus Immediate Stenting in High Thrombus Burden STEMI Patients

To compare the effect of immediate stenting versus deferred stenting - with use of glycoproteinIIbIIIa inhibitor & low molecular weight heparin - on the clinical outcome -3 and 6 months after stenting & also infarct size using troponin level during hospital stay .

Clinical outcome - 3 and 6 months - after stenting which includes re-infarction, repeat percutaneous coronary intervention, coronary artery bypass grafting , Congestive heart failure, cardiac death & cerebrovascular accidents.

Myocardial infarct¬¬¬ion is myocardial necrosis associated with impaired blood perfusion . Until now primary percutaneous coronary intervention (PPCI) is the standard modality of myocardial reperfusion However, there are a considerable number of patients whom still had acute reduction in myocardial blood perfusion after stent implantation even with patent epicardial artery which was defined as "no-reflow" That was explained by the affection of the micro-vasculature. With manipulation of culprit coronary artery lesion, distal embolization can occur, causing micro-vascular embolization & spasm which will significantly affect myocardial perfusion even with patent epicardial coronary artery Multiple methods were tried to decrease the chances of "no reflow phenomenon". Distal protection devices were used, but unfortunately with no promising results Routine thrombectomy is still controversial.

Deferred stenting, there is still controversy about the use of this strategy. At some studies, immediate stenting in thrombotic context was associated with no-reflow &distal embolization So ideas about deferred stenting started to glow when Isaac et al tried stenting deferral, after restoring culprit coronary artery patency using minimalist immediate mechanical intervention known as "MIMI - minimalist immediate mechanical intervention -" . That gave green light for further studies to explore benefits and risks of deferred stenting.

However , the strategy is still controversial , as some studies support the use of deferred stenting strategy and found it associated with better endpoints as, reduced no reflow , better myocardial perfusion and salvage lower major adverse cardiovascular events (MACE) , better left ventricular function

However there were other studies which showed no beneficial effect of deferred stenting, but even affect badly the micro-vascular obstruction. Reasons for these conflicting results included:

• Category of patients included where deferred stenting versus immediate stenting to prevent no- or slow-reflow in acute ST-segment elevation myocardial infarction (DEFER-STEMI) enrolled patients at high risk of slow flow based on clinical angiographic features, whereas DANAMI-3 DEFER was all-corner primary PCI study. A deferral strategy should only be applied after careful angiographic selection.
• DEFER-STEMI was angiographic and MRI end-point study whereas DANAMI 3-DEFER looked at clinical outcomes.
• DANAMI 3-DEFER was a larger multi-center randomized study in contrast to DEFER-STEMI.
• The use of GPIIbIIIa inhibitors in Deferred versus conventional stent implantation in patients with ST-segment elevation myocardial infarction (DANAMI 3-DEFER) was significantly lower compared to DEFERED-STEMI.
• There was high crossover to immediate stenting in the defer arm of DANAMI trial which further weakened the results.

Inclusion Criteria:

• Primary percutaneous coronary intervention (PPCI) patients with culprit vessels shows heavy thrombus burden lesions.
• Culprit vessels with TIMI 2-3 either from the beginning or after MIMI (Minimalist immediate mechanical intervention).

Exclusion Criteria:

• PPCI patients with low thrombus burden lesions.
• PPCI patient with heavy thrombus burden lesions but with culprit vessels TIMI score 0-1, didn't improve after MIMI.
• patients killip II /III /IV