Serial OCT-based coronary physiology and plaque composition in vessels with nonobstructive coronary lesions following...

Non-obstructive coronary plaques are a major source of future coronary events, particularly when characterized by high lipid burden and adverse plaque morphology. While intensive lipid-lowering therapy promotes plaque regression, serial data linking quantitative plaque compositional changes to coronary physiology are limited. We aimed to evaluate the impact of maximal lipid-lowering therapy on coronary plaque composition and coronary physiology, using artificial intelligence (AI) based tissue characterization derived from OCT and optical flow ratio (OFR).

This was a serial intravascular imaging sub-study of YELLOW III. Stable coronary artery disease patients with lipid-rich, non-obstructive plaques (diameter stenosis of 30-50% on angiography) received Evolocumab in addition to high-intensity statin therapy. Paired baseline and 26-week follow-up OCT and NIRS-IVUS imaging were available for 105 coronary segments. AI-based OCT was used for quantitative plaque characterization, and OFR was computed as a surrogate of invasive fractional flow reserve. Changes in plaque composition and coronary physiology were assessed, and correlations between compositional changes and OFR improvement were evaluated.

Amongst 105 paired coronary segments, total plaque volume decreased significantly over follow-up (201.2 ± 81.8 vs 191.3 ± 72.4 mm³; p < 0.001), driven primarily by reductions in lipid volume (p < 0.001) and macrophage volume (p = 0.006). Fibrous tissue volume showed a modest reduction, while its relative proportion increased, consistent with preferential lipid regression. Calcified plaque volume remained unchanged. Coronary physiology improved modestly, with an improvement in OFR (0.924 ± 0.062 to 0.932 ± 0.060; p < 0.001) and a reduction in lesion-level ΔOFR (p < 0.001). Improvement in OFR correlated inversely with reductions in total plaque volume (ρ = -0.286; p = 0.003), lipid volume (ρ = -0.257; p = 0.008), and lesion-level lipid burden assessed by LCBI (r = -0.23; p = 0.021).

Maximal lipid-lowering therapy induces favorable quantitative changes in plaque composition and modest but significant improvements in coronary physiology in non-obstructive coronary lesions. AI-based OCT with OFR provides an integrated approach to link plaque biology with functional remodeling.