Submit Manuscript | http://medcraveonline.com Abbreviations: CAC, coronary artery calcium; CAD, coronary artery disease; AAC, abdominal aortic calcifcation; CT, computed tomography; CKD, chronic kidney disease; NE, norepinephrine; HAART, highly active antiretroviral therapy; ASCVD, atherosclerosis cardiovascular disease; NAFLD, non-alcoholic fatty liver disease; MESA, multiethnic study of atherosclerosis; LDL, low density lipoproteins; HRT, hormonal replacement therapy; ROS, reactive oxygen species; PPAR-Ɣ, peroxisome proliferator activated receptor–Ɣ; ALP, alkaline phosphatase; SMC, smooth muscle cells; SHTC, second hand tobacco smoke; TNF, tumor necrosis factor; IL, interleukin; HDL, high density lipoproteins; VCAM, vascular cell adhesion molecule-1; ICAM, intracellular cell adhesion molecule–1; DECC, dual energy coronary calcium Introduction Coronary artery disease is the most common cardiovascular disease and is the leading cause of mortality worldwide. Early identifcation and intervention of coronary artery disease (CAD) and its risk factor decrease CAD related mortality by half. 1 Coronary artery calcium (CAC) deposits are a frequent component of atherosclerotic plaque 2 and are a subclinical marker of plaque burden in coronary artery diseases. CAC measurement by CT is a non-invasive method of quantifying the burden of coronary atherosclerosis, and it adds to the traditional method for risk stratifcation. CAC represents only one- ffth of total plaque content with the remaining four-ffth are the non- calcifed plaque. However, the amount of coronary artery calcifcation and CAC score is strongly correlated to cardiovascular risk. 3 Patients with a CAC score of 1-10 show a three-fold increased risk for coronary artery disease. 4 Risk of mortality from cardiovascular disease increases with each fold increase in the risk of coronary artery calcium. Calcium score above 100 infers fve folds’ increase risk of mortality from cardiovascular diseases. Sizes and numbers of CAC deposits determine the type and prognosis of coronary artery disease. Plaques with many small calcium deposition foci are present in a patient with unstable coronary artery disease, and myocardial infarction. Whereas, plaques with few large calcium deposits are present in patients with the stable coronary artery disease. 5,6 Small deposition of calcium increases the risk of plaque rupture especially at the edges whereas the risk of fracture decreases with extensive calcifcation. 7,8 CAC is often present in a low-risk patient of cardiovascular disease and absent in high-risk patients for cardiovascular disease. 9 Early detection of CAC could improve the risk of cardiac diseases because CAC scanning leads to a healthy lifestyle, increase use of statins and aspirin based on elevated risk on CAC fndings, and increase patient compliance to medication. 10,11 This review summarizes the pathogenesis, factor affecting coronary artery calcium and the use of chest X rays as a new way of detecting coronary artery calcium. The purpose of this review is to provide a compiled knowledge of coronary artery calcium and provide directions for more research. CAC and chest X rays CT scan is the current modality of measuring CAC. CT scans have limitations of high cost and radiation dose. Recently, Di Wen at al developed and studied the use of dual-energy coronary calcium (DECC) processing method for CAC detection through dual energy chest radiograph, which provides low cost and radiation solution to CAC screening. 12 Before this study, Neves et al. 13 reported a case of CAC detection in routine chest radiograph in a patient with the end- stage renal disease. These studies divert our attention towards the use of Chest X rays – dual energy or routine Chest X rays– for coronary artery calcium detection and demand more research in this regard. 13 Correlation between CAC in Chest X-ray and CT scan should be studied so that X rays can be used to determine CAC score which would make a detection of CAC and cardiovascular risk cheaper. Pathogenesis of CAC Coronary artery calcium formation is an organized metabolic process which is similar to bone formation. Calcifcation occurs in both intima (atherosclerotic) as well as in media of coronary arteries. Infammatory mediators and elevated lipid content within atherosclerosis are associated with intimal calcifcation whereas diabetes, advanced age and chronic kidney diseases (CKD) are associated with medial calcifcation. 14,15 Three common steps of coronary artery calcifcation are: a. Osteoblastic differentiation b. Bone-associated proteins formation c. Mineralization Int J Radiol Radiat Ther. 2018;5(6):318‒323. 318 © 2018 Iqbal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Coronary artery calcium–a review article Volume 5 Issue 6 - 2018 Aqsa Iqbal, 1 Abid Hussain, 2 Anum Iqbal 3 1 Department of Physiology & Biophysics, University of Illinois at Chicago, USA 2 Nishtar Medical University, Pakistan 3 Liaquat University of Medical & Health Sciences, Pakistan Correspondence: Aqsa Iqbal, Department of Physiology & Biophysics, University of Illinois at Chicago, Chicago, Illinois, 60610, USA, Email Received: September 03, 2018 | Published: November 19, 2018 Abstract Coronary artery calcium represents a subclinical marker of atherosclerotic plaque burden in coronary artery disease. Coronary artery calcium detection has been in use for a long time to stratify the risk of coronary artery disease. This review talks about the pathogenesis, Chest X ray as a detection modalities of coronary artery calcium, and describe factors affecting coronary artery calcium. The purpose of this review is to provide a compiled knowledge of coronary artery calcium and provide directions for more research. Keywords: coronary artery calcium, chest X rays, pathogenesis, factors, coronary artery disease International Journal of Radiology & Radiation Terapy Review Article Open Access