Vessel-level patterns and predictors of discordance between computed tomography coronary angiography and invasive coronary angiography

Abstract

BACKGROUND

Coronary calcification is a recognized source of computed tomography coronary angiography (CTCA) stenosis overestimation. We evaluated whether discordance between CTCA and invasive coronary angiography (ICA) also shows clinically relevant vessel-territory patterns in a selected real-world paired-imaging cohort.

AIM

To evaluate patient- and vessel-level CTCA diagnostic performance, quantify territory-specific discordance, assess three-category stenosis agreement, and identify predictors of discordance in a selected paired-imaging cohort.

METHODS

We systematically screened the hospital CTCA database for October 2019-December 2024 and included consecutive adults with paired CTCA and ICA within 120 days, subject to the study exclusions. After reviewing interval revascularisation, we excluded one patient in whom percutaneous coronary intervention (PCI) occurred after diagnostic ICA but before the subsequent CTCA, leaving 403 patients and 1612 major epicardial vessel observations. Severe/occlusive disease was the positive binary endpoint, with a left main coronary artery (LMCA)-specific severe threshold of ≥ 50% in both modalities. Patient-level predictors were assessed with logistic regression and vessel-level predictors with mixed-effects logistic regression using a patient random intercept.

RESULTS

ICA demonstrated severe/occlusive disease in 204/403 patients (50.6%). Patient-level sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 91.7% (95%CI: 87.0%-95.1%), 35.2% (95%CI: 28.6%-42.2%), 59.2% (95%CI: 53.5%-64.6%), and 80.5% (95%CI: 70.6%-88.2%), respectively. Across 1612 vessels, sensitivity was 80.8% (cluster-bootstrap 95%CI: 76.3%-85.1%), specificity 81.7% (95%CI: 79.5%-83.7%), PPV 50.4% (95%CI: 45.4%-55.2%), NPV 94.9% (95%CI: 93.5%-96.1%), and discordance 18.5% (95%CI: 16.6%-20.3%). At least one discordant vessel was present in 229 patients (56.8%). Discordance was highest in the left anterior descending artery (LAD) (31.8%) and lowest in the LMCA (2.5%). Three-category agreement was moderate (weighted kappa 0.500, 95%CI: 0.459-0.539). Calcium burden remained independently associated with discordance at the patient level [odds ratio (OR) = 1.66 per category, 95%CI: 1.03-2.73; P = 0.042] and vessel level (OR = 1.40, 95%CI: 1.04-1.87; P = 0.025). The LAD had higher adjusted odds of discordance than the right coronary artery (OR = 1.82, 95%CI: 1.32-2.53; Holm-adjusted P = 0.0003) and left circumflex artery (OR = 2.01, 95%CI: 1.44-2.80; Holm-adjusted P < 0.001).

CONCLUSION

In this selected cohort of patients who underwent both CTCA and ICA, greater visual coronary calcium burden was associated with anatomical discordance, and discordance varied by epicardial territory, being highest in the LAD. Because referral for ICA was selective, study readings were not independently blinded, and ICA stenosis was visually graded, the observed diagnostic metrics may not generalise to unselected CTCA populations. No downstream testing pathway, invasive-referral decision, or patient outcome was evaluated; the findings are descriptive and hypothesis-generating.

Keywords: Computed tomography coronary angiography; Invasive coronary angiography; Coronary artery disease; Diagnostic discordance; Coronary calcium burden; Stenosis severity; Epicardial vessels; Mixed-effects modelling

Core Tip: In this selected real-world cohort undergoing paired computed tomography coronary angiography (CTCA) and invasive coronary angiography (ICA), greater visual patient-level coronary calcium burden was associated with discordance at both patient and vessel levels, confirming a recognised limitation of CTCA in calcified disease. Discordance varied substantially by epicardial territory, with the left anterior descending artery showing the highest and left main coronary artery the lowest observed rates. These findings are consistent with treating a severe CTCA result as the beginning of a clinical decision process rather than as an automatic indication for ICA: The anatomical abnormality should be reconciled with symptoms and overall clinical context, with functional assessment considered where appropriate and ICA used when invasive clarification is clinically warranted. The territory-specific pattern and hierarchical analysis add descriptive information beyond the established calcium effect, but these findings are hypothesis-generating and require external validation with blinded reproducibility assessment, quantitative calcium measurement, and physiological or intravascular correlation.