Comparative review of coronary CT angiography versus conventional catheter angiography: diagnostic value, clinical outcomes, and underlying technical principles

INTRODUCTION: The diagnostic pathway for coronary artery disease (CAD) is actively transitioning toward noninvasive risk stratification. This review contrasts Coronary Computed Tomography Angiography (CCTA) with Invasive Coronary Angiography (ICA) to clarify their respective roles and physical limitations in modern cardiovascular care. AREAS COVERED: A comprehensive literature search was conducted across PubMed, Web of Science, and Scopus for articles published between January 2015 and March 2026. We evaluate the physical principles, diagnostic performance, and clinical utility of both imaging modalities. The discussion includes recent breakthroughs like Photon-Counting Detector CT (PCD-CT), which improves stenosis grading in heavily calcified lesions. We also explore CCTA's expansion beyond basic morphology into functional and prognostic assessments via CT-derived Fractional Flow Reserve (FFR-CT), artificial intelligence algorithms (AI-QCT), and the Pericoronary Fat Attenuation Index (FAI). EXPERT OPINION: Current clinical evidence supports a 'CCTA-first' approach for stable chest pain. CCTA functions as the primary noninvasive gatekeeper and platform for plaque phenotyping, while ICA remains the irreplaceable standard for high-risk diagnostics and targeted therapeutic revascularization.