Associations of lesion-specific pericoronary adipose tissue attenuation and CT-derived fractional flow reserve with coronary stenosis progression: a retrospective selected-lesion study

Background Coronary disease that is non-obstructive at baseline may progress, while luminal stenosis alone does not capture local pericoronary tissue characteristics or lesion-specific functional impairment. Objective To assess associations of lesion-specific pericoronary adipose tissue (PCAT) attenuation and CT-derived fractional flow reserve (CT-FFR) with imaging-defined stenosis progression and to evaluate an exploratory multivariable model. Methods This retrospective single-center study included 201 patients undergoing serial coronary computed tomography angiography with selected target lesions classified as minimal or mild at baseline. In progressors, the lesion with the greatest follow-up progression was selected; in non-progressors, the lesion with the greatest baseline stenosis was selected. Thus, target-lesion selection was outcome dependent. Lesion-specific PCAT and CT-FFR were quantified using dedicated automated software after target-lesion identification. Five logistic models specified before reanalysis fitting were fitted in a common complete-case population ( n = 191), and Model E retained nine predictors. Internal performance was assessed with 2,000 patient-level bootstrap resamples. Results Progression occurred in 115 of 201 patients. In Model E, less-negative PCAT attenuation (odds ratio [OR] per 10-HU increase, 1.552; 95% CI, 1.137–2.119; P = 0.006) and lower CT-FFR (OR per 0.05 decrease, 1.360; 95% CI, 1.041–1.778; P = 0.024) were associated with progression; age showed an inverse conditional association (OR per 10-year increase, 0.509; 95% CI, 0.346–0.749; P < 0.001). Model E had an apparent AUC of 0.767 (95% CI, 0.700–0.834) and an optimism-corrected AUC of 0.722 (95% bootstrap interval, 0.659–0.787). The corrected Brier score was 0.217 (0.189–0.251), calibration intercept −0.0002 (−0.354 to 0.361), and calibration slope 0.779 (0.539–1.100). Versus Model B, corrected Δ AUC was 0.053 (−0.005 to 0.088), indicating apparent improvement with uncertainty. Conclusions Less-negative lesion-specific PCAT attenuation and lower CT-FFR were associated with imaging-defined stenosis progression. The combined model showed moderate optimism-corrected discrimination, but incremental discrimination remained uncertain. Because lesion selection in progressors incorporated follow-up information and no external validation was available, this internally derived model is exploratory and is not a clinically validated decision tool.