Aims

To evaluate the ability of AI-based quantitative CT (AI-QCT) parameters, diameter stenosis, percent atheroma volume (PAV) and average lumen area (ALA) to rule-in or rule-out ischemia.

Methods and results

This post-hoc, vessel-level analysis included patients with suspected CAD from the CREDENCE (612 patients; 1727 vessels) and PACIFIC-1 (208 patients; 612 vessels) studies who underwent CCTA and invasive FFR. In addition to diameter stenosis, PAV and ALA were evaluated as key predictors of ischemia. We report abnormal FFR prevalence based on these variables and define rule-out (<15% ischemia prevalence, defer further testing), rule-in (>75% prevalence, ischemia highly likely; further testing typically unnecessary) and intermediate risk (15–75%, consider additional functional assessment). PAV and ALA were dichotomized using median values derived from the CREDENCE cohort (14.7% and 3.9 mm²) and validated in PACIFIC-1. In CREDENCE, all vessels with 1–24% stenosis were ruled-out. Among vessels with 25–49% stenosis, 74% met rule-out criteria, while 26%, characterized by large PAV and small ALA, were intermediate risk. Within the proposed framework vessels with 50–69% stenosis were classified as intermediate risk. For 70–99% stenosis, 93% met rule-in criteria, except a small subset with small PAV and large ALA. In PACIFIC-1, 86% of vessels with <50% stenosis were ruled-out, and 61% of those with 50–99% stenosis were ruled-in.

Conclusion

A simplified framework incorporating AI-QCT parameters including diameter stenosis, PAV (>14.7%), and ALA (<3.9 mm²), stratifies myocardial ischemia risk. Most non-obstructive lesions can be ruled-out, while most stenoses >70% are reliably ruled-in. This practical approach enhances the diagnostic utility of CCTA and streamline clinical decision-making.