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Abstract Summary Summary Coronary stent implantation has become the new standard angiop.lasty procedure, and has fundamentally changed the practice of interventional cardiology by reducing early complications and improving the late clinical outcomes in a broad array of patients. The present study was conducted in a trial to determine the frequency of stent thrombosis and to provide a better understanding of the underlying factors responsible for stent thrombosis, and it aimed also at examining the short-term clinical outcomes of the new Drug Eluting Stents (DES), which were primarily invented to combat long-term 10- stent restenosis compared to conventional bare metal stents. The sample included 60 patients who were classified according to the type of stent received into 2 groups each included 30 patients. The first group (Group I) included 30 patients (their ages ranged from 41 to 75 years with mean age of 57.9±8.6) who were treated with drug-eluting stents, and the second group (Group II) included 30 patients (their ages ranged from 41 to 77 years with mean age of 57.2±10.55) who were treated with conventional stents. The patients were followed up for the occurrence of major cardiac events (death, myocardial infarction, target lesion revascularization) or angiographically documented stent occlusion within a mean time interval ofl month. There were no significant differences between group I and group II regarding age, sex, DM, hypertension, hyperlipidemia, smoking, prior MI and prior PCI. However, group I included more patients with past history ofCABG than group II [5 patients in group 1(16.7%) vs.l patient (3.3%) in group II (p<0.05)]. 128 -- Summary The mean and standard deviation of LVEF in group I were 54.7±7.4%, while in group II were 59.4±9%. LVEF was significantly lower in group I than in group II [p<0.05]. There was a significant difference between group I and group II regarding the type of stented vessel; group I included more patients who received stents for LAD lesions than group II [20paients (66.6%) in group I vs. 11 patients (36.7%) in group II, (p<0.05»). Group I included more patients with multi-vessel disease than group II [12 patients (40%) in group I had multi-vessel disease vs. 5 patients (16.7%) in group II (p<0.05»). There was a significant difference between group I and group II regarding the number of stents deployed per patient; the number of patients who received more than one stent was higher in group I than it was in group II [9 patients in group I (30%) vs. 3 patients (10%) in group II (p<0.05)]. There was a significant difference between group I and group II regarding sub-optimal stent expansion; 5 patients (16.6%) in group I had sub-optimal results compared to only one patient (3.3%) in group II (p<0.05). Regarding the presence of slow flow after stent deployment, there was a significant difference between group I and group II; group I included 4 patients (13.3%) with slow flow while no patients (0%) in group II had slow flow after stent deployment (p<0.05). There was no significant difference between group I and group II regarding the presence of residual dissections. However, group I included more patients with residual dissections after stent deployment than group II [4 patients (13.3%) in group I vs. I patient (3.3%) in group II (p>0.05)]. 179 ------------ Summary Regarding the presence of pre-intervention thrombus, there was a significant difference between group I and group II; the incidence of preintervention thrombus was higher in group II than in group I [no patients (O%)-in group I vs. 4 patients (13.3%) in group II (p<O.05)]. Nevertheless, only one of those patients who had pre-intervention thrombus suffered from subacute stent thrombosis. The mean diameter of stents deployed in group I was larger than the mean diameter of stents implanted in group II [ 3.2±0.34 rom in group I vs. 3.I±O.3mm in group II (p<O.OI»). The mean length of stents deployed in group II was longer than the mean length of stents implanted in group I [17.3±3.25mm in group I vs. 20.9±4.6mm in group II (p<O.OI)]. -There was no significant difference between group I and group II regarding the inflation pressure. Routine high-pressure inflation (~14 ATM) was applied in most of the cases. There were also no significant differences between group I and group II regarding clinical presentation or ACC/ AHA type of lesion. The incidence of stent thrombosis was higher in group I than in group 11[4 patients (13.3%) in group I suffered from stent thrombosis vs. only one patient (3.3%) in group II]. However, this didn’t reach statistical significance (p>O.05). Three patients from those who suffered stent thrombosis in group I had post procedural MI vs. one patient in group II (p>O.05). Among those who experienced stent thrombosis, two patients in group I needed emergency catheter based revascularization versus one patient in group II (p<O.05). Only one patient from those receiving drugeluting stents died after the occurrence of stent thrombosis while no patients died in group II, with overall mortality rate 1.7%. 130 __________________ ------ Summary In the present study, some factors had relatively higher risk for stent thrombosis than the others, and some of these factors were suggested to be predictors of stent thrombosis. The presence of slow flow after stent deployment, the presence of residual dissections., sub-optimal stent expansion, the number of stents deployed per patient and low LVEF were suggested to be strong predictors of stent thrombosis. It is recommend that multiple stents and longer stents should be used only when needed to cover significant extrastent stenosis or dissection. The overall clinical experience with the drug-eluting stent doesn’t suggest an increased propensity for stent thrombosis. Nevertheless, some precautions have to be followed regarding the safety of drug-eluting stents, such as the need of higher inflation pressure, appropriate sizing, extension of post procedural dual antiplatelet therapy, optimally, to one year and the use of glycoprotein Ilb/IlIa inhibitors for complex stent procedure, long stents and/or procedure that require multiple drug-eluting stents. 1’11 |