Introduction
Accelerated atherosclerosis (AA), so-called rapid atherosclerosis, of proximal coronary segments is a well-established syndrome after coronary artery bypass grafting surgery (CABG).1–3 Initial reports showed that coronary artery segments proximal to severe luminal stenosis develop rapid atherosclerotic progression after CABG.1 A similar phenomenon was described after CABG in the grafted coronary artery segments with luminal stenosis of <50% as well as in normal segments lying between a high-grade stenosis and the anastomosis site.2–4
Spontaneous atherosclerosis has a complex evolution which consists of six distinguishable stages, each with particular morphological characteristics related to the changes in lipid accumulation, thrombotic deposits and calcification.5 In contrast, AA describes an exceedingly aggressive subset with a pathophysiology involving a denuding injury of the vascular intima and endothelium followed by thrombosis and proliferation of the smooth muscle cells and subsequently fibrosis results in the rapid progression of the lesions. Atheroma containing calcium is considered as an advanced atherosclerotic lesion and is classified as type V.5 Since total coronary calcium strongly correlates with total plaque burden and the average coronary calcium area is approximately 20% of the total histological plaque area,6 7 quantification of coronary artery calcium by CT provides an estimation of an extent and progression of coronary atherosclerosis.
Coronary CT is the reference tool to quantify coronary artery calcium (CCS) and to differentiate calcified from non-calcified plaques. In contrast, invasive coronary angiography was used in previous reports to assess AA post CABG and is a lumenogram that has a major limitation in determining coronary artery wall composition.8
To date, there are no reports that analyse the progression rate of calcium in the coronary artery tree after CABG. The aim of this study is to determine the progression of CCS post-CABG using CT and determine whether it differs from that of the non-grafted vessels.