Difference in Grading of Coronary Stenosis Between Coronary CT Angiography and Invasive Coronary Angiography: Our Experience in an Egyptian Population

Background: There is some disagreement on grading of coronary artery stenosis (CAS) between CT coronary angiography (CTA) and Invasive Coronary Angiography (ICA). However, there is paucity of data about the factors causing inaccuracy of CTA in grading of CAS. The aim of this study is to identify coronary arterial segment characteristics associated with inaccurate stenosis grading by CTA as defined by Invasive Coronary Angiography (ICA) in an Egyptian population. Methods: The study was a retrospective single center clinical investigation including 84 patients who were referred for CTA and ICA for various appropriate reasons. We have analyzed the concordance of the stenosis grades on ICA and CTA and their correlation. The difference of grades (DG) between ICA and CTA has been compared across the following variables: involved coronary artery ( left main (LM), left anterior descending (LAD), left circumflex (CX) and right coronary artery (RCA)), anatomical stenosis level (proximal, mid and distal), plaque type (Non-calcified, calcified and mixed) and the ICA stenosis grades (1, 2, 3, 4 and 5). Results: The linear weighted kappa was к = 0.65 (Confidence Interval: 0.59-0.71) and Spearman's rs = 0.80 (p < 0.001; Confidence Interval: 0.75-0.85). No association was noted between difference of grades (DG) and involved coronary artery (p = 0.092). A significant association was found between the DG and the affected anatomical segment (p = 0.005) with a significant difference between stenosis of the distal segments versus proximal and middle segments. There was a significant association between DG and plaque type (p = 0.021) with a significant difference between calcified and non-calcified plaques. A significant association between DG and stenosis grade (p < 0.001) was noted but it was considered as clinically irrelevant. Conclusion: Distal segments stenosis and calcified plaques are associated with higher risk of CTA stenosis grade overestimation.