Assessing Calcified Coronary Lesions to Guide Percutaneous Coronary Intervention: From Angiography to Intracoronary...

Background/Objectives: Coronary artery calcification is a leading cause of stent failure and a strong predictor of adverse outcomes after percutaneous coronary intervention (PCI). Accurate characterization of calcium burden, depth, and morphology is central to procedural planning, targeted treatment, and better outcomes. This review summarizes the contemporary armamentarium for imaging calcified coronary lesions, from coronary angiography and computed tomography to advanced intracoronary imaging, and how it facilitates treatment. Methods: We synthesized evidence from landmark studies, validated imaging scoring systems, registries, and current guideline and consensus documents addressing the assessment and imaging-guided treatment of coronary calcification. Results: Invasive angiography shows poor diagnostic accuracy for coronary calcium detection, characterization, and quantification. Coronary CT angiography noninvasively quantifies calcium (Agatston score and three-dimensional volume) and supports preprocedural planning, although it may overestimate calcium volume. Intravascular imaging by means of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) effectively detects coronary calcium. Their use is associated with improved clinical outcomes compared with sole angiographic guidance. The addition of near-infrared spectroscopy (NIRS-IVUS) characterizes lipids within calcified plaque and high-risk calcified nodules. OCT provides the highest spatial resolution and uniquely measures calcium thickness and longitudinal calcium length, while the utilization of artificial intelligence further enhances calcium assessment. Integration of these modalities into a morphology-based, imaging-guided approach facilitates calcium detection and modification and supports PCI optimization. Conclusions: Intravascular imaging, along with coronary CT angiography, has transformed the assessment of calcified coronary lesions. Combining their strengths enables precise, lesion-specific preparation; randomized trials show that intravascular imaging guidance improves outcomes in complex PCI, while CT-guided PCI planning is emerging as a complementary strategy whose clinical value is now being tested in randomized trials.