PCCT-Defined High-Risk Plaque and Future Coronary Events: The PREDICT Study

Photon-Counting Detector CT (PCCT) enables improved spatial resolution and spectral tissue characterization, allowing non-invasive detection of high-risk coronary plaque (HRP) features such as low-attenuation plaque (<30 HU), positive remodeling (index ≥1.1), spotty calcification, and the napkin-ring sign. The presence of ≥2 of these features defines a PCCT-detected high-risk plaque. Optical Coherence Tomography (OCT), an invasive high-resolution imaging tool, defines HRP by thin-cap fibroatheroma (fibrous cap thickness <65 μm, lipid arc >90°) and other vulnerable features. While OCT provides detailed information on plaque vulnerability, it is invasive and limited to selected vessels. The prognostic significance of PCCT-defined HRP, and its diagnostic agreement with OCT, remain to be fully established.

This prospective, single-centre study will enroll patients with acute or stable coronary syndromes who are scheduled for clinically indicated invasive coronary angiography and OCT evaluation of at least one native coronary artery. All participants will first undergo a dedicated contrast-enhanced PCCT coronary angiogram. Within 30 days after PCCT, participants will undergo invasive coronary angiography with OCT imaging. Thus, OCT is systematically acquired after the CT, allowing a cross-sectional diagnostic comparison where PCCT findings are evaluated against the OCT reference. Both imaging datasets will be analyzed by independent core laboratories blinded to each other's results and to clinical data.

The study has two integrated components:

• Prognostic component - The primary objective is to assess whether the presence of PCCT-defined HRP independently predicts the 2-year incidence of MACE (cardiovascular death, non-fatal myocardial infarction, hospitalization for unstable angina requiring urgent revascularization). The primary hypothesis is that MACE rate is significantly higher in patients with PCCT-HRP than in those without.
• Cross-sectional diagnostic comparison - Using OCT as the invasive reference, the diagnostic performance of PCCT for identifying high-risk plaque will be determined. Per-patient and per-lesion sensitivity, specificity, positive and negative predictive values, and overall accuracy of PCCT will be calculated and compared with OCT-derived high-risk plaque classification.

Participants will be followed prospectively for MACE and unplanned revascularization over 24 months.

Inclusion criteria

• Age ≥18 years
• Scheduled for clinically indicated, non-emergent invasive coronary angiography
• Provision of written informed consent and willingness to comply with long-term follow-up

Exclusion criteria

• Estimated glomerular filtration rate <45 mL/min/1.73 m²
• Known allergy to iodinated contrast media
• Pregnancy or breastfeeding
• Persistent atrial fibrillation or other arrhythmia precluding adequate ECG-gated CT acquisition
• Body mass index >40 kg/m²
• Target vessel with a previously implanted stent
• Life expectancy <2 years or any condition that, in the opinion of the investigator, makes follow-up unlikely or participation inappropriate