Objective: This study aimed to assess and compare the diagnostic performance of the coronary artery to aortic luminal attenuation ratio (CAR), transluminal attenuation gradient (TAG), and corrected coronary opacification (CCO) difference on coronary CT angiography (cCTA) for detecting haemodynamically significant coronary artery stenosis. Methods: 33 patients who underwent cCTA, gated SPECT myocardial perfusion imaging (MPI), and invasive coronary angiography within 3 months were included in this retrospective study. The degree of coronary stenosis on cCTA was visually assessed in all patients. Additionally, CAR, TAG, and CCO difference were analyzed and calculated in all patients. Haemodynamically significant coronary stenosis was defined as a vessel with ≥50% luminal stenosis on invasive coronary angiography and an associated abnormal perfusion defect on MPI in the same territory. Diagnostic performance was assessed on a per-vessel basis by the area under the receiver operating characteristic (ROC) curve (AUC). Results: Among 99 vessels, 12 were excluded and the remaining 87 were analyzed. 17 (19.5%) vessels were determined as haemodynamically significant coronary artery stenosis. On ROC analysis, the AUC was 0.71 for cCTA, 0.80 for CAR, 0.61 for TAG, 0.74 for CCO, 0.87 for combined CAR and cCTA, 0.77 for combined TAG and cCTA, and 0.75 for combined CCO and cCTA. The AUC for combined CAR and cCTA was significantly greater compared with cCTA alone (p < 0.01). Conclusion: Non-invasive CAR derived from 64-detector row CT was feasible and might be helpful for the detection of haemodynamically significant coronary artery stenosis. Still, further investigations such as intra- and inter-reader correlation, evaluation of larger numbers in different settings, and time efficiency are required for applying CAR in various situations. Advances in knowledge: CAR could be used as novel noninvasive technique to detect haemodynamically significant coronary artery stenosis.

GroupsAmong these 242 patients, 226 underwent either ischemia-driven or planned follow-up coronary angiography within 8 months. Thus, *Corresponding author: Manabu Shirotani, Cardiology Department, Nara Hospital, Kinki University Faculty of Medicine, 1248-1, Otoda-Cho, Ikoma, Nara, 630-0293, Japan, Tel: +81 743 77 0880; Fax: +81 743 77 0901; E-mail: manabu@nara.med.kindai.ac.jp AbstractBackground: Bare Metal Stents (BMS) have been commonly used for recanalization of an infarct-related artery in Japanese patients with Acute Myocardial Infarction (AMI). We sought to examine predictors of binary restenosis and early Stent Occlusion (SO) in these patients. Methods:Among 242 consecutive patients with AMI treated by BMS implantation as reperfusion therapy, 226 underwent either ischemia-driven or follow-up coronary angiography within 8 months. Restenosis change in the stented segment was found in 56. Among them, 10 patients had early SO on an angiogram. Multivariate analysis was performed to obtain predictors of restenosis and early SO.Results: Predictors for restenosis were Left Anterior Descending Artery (LAD) involvement (odds ratio (OR) 2.32, p=0.024), serum creatinine (SCr) on admission (OR 1.29 per 0.1mg/dl increase, p=0.001), and stent size (OR 0.43 per 0.5mm increase, p=0.001). Those for early SO were left main trunk or LAD involvement (OR 27.0, p=0.029), SCr (OR 1.65 per 0.1mg/dl increase, p=0.005) and leukocyte count (OR 1.28 per 1,000/microliter increase, p=0.037) on admission. SCr was significantly higher in patients with early SO than in those with restenosis (median 1.05, Interquartile Range (IQR) 0.80-1.10 vs. median 0.80, IQR 0.70-1.00, p=0.035). Conclusion:In patients with AMI treated with BMS, both restenosis and early SO were increased by anterior wall involvement and elevation of SCr level. Higher SCr may be subject to more occlusive changes. It is suggested that in early SO, an inflammatory mechanism may be involved.