الفهرس 
INTRODUCTION
PATHOPHYSIOLOGY OF MYOCARDIAL ISCHEMIAOnly 14 pages are availabe for public view
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Abstract
This study was conducted at departments of Cardiothoracic Surgery in Assiut and Minia University Hospitals, between November 2014 and October 2016. All survivor patients completed a follow-up period of 6 months after CABG. The study included 100 patients who underwent isolated elective on-pump CABG. group I included patients with LVEF < 50% (reduced LVEF; n=50); and group II patients included equal number of patients with LVEF ≥ 50% (normal LVEF; n=50). The study excluded patients with concomitant valve replacement, previous cardiac surgery, redo-CABG, emergency surgery, and hepatic failure, renal failure on dialysis, aneurysm repair, overt peripheral vascular disease, surgery for arrhythmia, repair of ventricular septal perforation, concomitant carotid artery surgery, and absence of myocardial viability. The study was conducted in accordance with the Helsinki Declaration. An approval from a research ethics committee and informed consents from patients were obtained. Routine preoperative laboratory and radiological investigations for cardiac surgery were performed for all patients including angiographic and echocardiographic studies. To evaluate myocardial viability in patients with reduced LVEF, preoperative DSE was performed. Echocardiography was repeated in the first week after surgery and at 6th month during the follow-up period. The primary end point was early in-hospital mortality defined as death within the same hospital admission including operating room death and the deaths occurring within 30 days postoperatively. Early 30 days in-hospital mortality was 8% (4 patients) in patients with LVEF < 50% (group I) and 4% (2 patients) in patients with LVEF ≥50% (group II), with insignificant difference. In subgroup of patients with LVEF ≤ 35% (n=7), early mortality was in one patient (14.3%). The causes of death were cardiogenic shock in 4 patients (3 patients in group I and one patient in group II), multi-organ system failure in one patient of group I and respiratory insufficiency in another one patient of group II. Preoperative change in WMSI on DSE had more prognostic accuracy than change in LVEF in patients with reduced preoperative LVEF. There were no significant differences in postoperative complications, except for the occurrence of LCOS in group I which was significantly higher than group II (44% versus 26%, P = 0.04). Also, in subgroup of patients with LVEF ≤ 35%, LCOS had statistically significant higher frequency than subgroup of patients with LVEF >35% (71.4% versus 32.3%, P = 0.03). Most of the patients in group I had significant improvement of LVEF ≥ 5% at the end of 6 months follow-up than immediately after surgery (80.4% versus 28.3%, P<0.001). The preoperative frequency of NYHA class III and IV decreased significantly from 30% to 8.7% (P = 0.03) at end of 6 months follow-up. In patients with preoperative reduced LVEF <50%, the use of IABP was a significant predictor of early mortality. Smoking and incomplete revascularization were significant predictors of LCOS. Sternal wound infection and LCOS were significant predictors of prolonged length of postoperative hospital stay > 7 days in survivors. Acceptable early postoperative outcome can be achieved after CABG in patients with reduced LVEF (<50%). Successful results of CABG in patients with reduced LVEF (<50%) can be obtained by careful selection of patients and proper management. The benefit of CABG in patients with reduced preoperative LVEF is related to postoperative improvement of LVEF and NYHA functional class. The identification of significant peri-operative risk factors associated with operative mortality and morbidity is important for adequate preoperative patient selection and to evaluate the quality of treatment. Evidence of myocardial viability using DSE is essential to determine the beneficial effects of CABG in patients with reduced LVEF. Preoperative assessment of WMSI using DSE has higher prognostic accuracy than LVEF in patients with LV systolic dysfunction, and it helps identify patients who may benefit most from CABG. Prolonged hospital stay after CABG in patients with preoperative LVEF <50% is associated with postoperative LCOS and SWI. A protocol-based approach should be developed to reduce postoperative adverse events after CABG in regard to peri-operative risk factors mainly in high risk patients including patients with reduced LVEF.