Computed tomography coronary angiogram in left main stem disease: how does it fare against invasive coronary angiography?

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Computed Tomography Coronary Angiography (CTCA) is increasingly being used to detect and exclude the presence of coronary artery stenosis. Published studies to date comparing CTCA to invasive coronary angiography (ICA) have focused on epicardial vessels other than the left main stem (LMS) (1 - 4). Despite the diagnostic accuracy of CTCA specifically for LMS disease being unknown, it has been used in a recent multi-centre trial (5). Purpose To evaluate the diagnostic performance of CTCA compared with ICA for the detection and visual grading of native Left Main Stem lesions. Methods Retrospective study of patients who underwent CTCA and ICA within 12 months as part of a Quality Improvement project, with no prior coronary intervention. CTCA LMS lesions were graded by consensus of 3 independent blinded reviewers using the Coronary Artery Disease - Reporting and Data System (CAD-RADS) (none, minimal, mild, moderate and severe) and ICAs were similarly evaluated by consensus of 2 independent, blinded reviewers. Moderate and severe LMS lesions were considered clinically significant. Results A total of 53 subjects underwent both CTCA and ICA (70% male, mean age: 62). 66% of LMS lesions were found to be significant on ICA. Compared to ICA, CT angiography has a sensitivity of 83% and a specificity of 89% for detecting a significant LMS stenosis of 50% or more, with a positive predictive value of and a negative predictive value of 94% and 73% respectively. CTCA for detecting a significant LMS stenosis has a AUC of 0.88. In stenosis grading, CTCA correlated with ICA at the same CAD-RADS level in 53% of cases, with over-estimation in 19% and under-estimation in 28% of cases. Conclusion In this retrospective single centre study of patients with native coronary vessels, CTCA is shown to be accurate in identifying significant LMS lesions detected on ICA. However, at a level of stenosis grading, there is significant inter-modality discrepancy with CTCA associated with over- and under-estimation of LMS lesion severities compared with ICA. Diagnostic Performance of CTCA vs ICA Significant LMS lesion ICA positive ICA negative CTCA positive 29 2 CTCA negative 6 16 Diagnostic Performance of CTCA vs ICA in significant LMS lesions Abstract Figure. Significant LMS lesions:CTCA performance