Coronary Artery Bypass Graft Failure and Its Relationship to Target Artery Percentage Stenosis and Competitive Flow. A CT Angiographic Analysis

The Coronary Artery Bypass Graft (CABG) failure is a cause of major cardiac events. CABG to coronary arteries with low-grade stenosis resulting in competitive flow and graft failures is a controversial issue. Some studies refute this. All of these studies have been performed with Invasive Catheter Angiogram. This study is the first one to investigate the relationship between CABG failure and chronic competitive flow with Coronary CT Angiogram. 1445 grafts in 438 patients were studied. The degree of stenosis of the grafted coronary artery was obtained from the preoperative ICA. The post-CABG CTA was performed on the Aquilion 64 and Aquilion One 320 slice scanners. The study group was divided according to graft types into LIMA + Right internal mammary artery, SVG and left radial artery. Each type was further divided into “Patent” and “Failed” groups. The two groups were compared for target artery percentage stenosis below and above 75%. Each graft type was further divided into subgroups according to years after CABG and compared similarly. 72% of total grafts including LIMA, RIMA, SVG and LRA when placed on coronary arteries with less than 75% stenosis failed as compared to 22.8% grafts failing when placed on coronary arteries with more than 75% stenosis (p < 0.0001) irrespective of number of years post CABG. When faced with competitive flow all graft types fail equally irrespective of number of years post CABG.