Qualitative and quantitative evaluation of dynamic changes in non-culprit coronary atherosclerotic lesion morphology: a longitudinal OCT study

Aims: There is limited in vivo evidence regarding the temporal evolution of non-culprit coronary plaque morphology. We aimed to evaluate changes in non-culprit plaque morphology over time by optical coherence tomography (OCT). Methods and results: Seventy-two (72) patients with 257 non-culprit segments with serial OCT studies were analysed. Non-culprit 5 mm-long coronary segments from the same imaged region were matched between baseline and follow-up. OCT plaque characterisation including automated attenuation analysis was performed, and changes over a median follow-up of 6.2 months were evaluated. On segment level, lumen area decreased from baseline to follow-up, whereas fibrous cap thickness increased. Similarly, plaque attenuation indices at follow-up were significantly decreased. Minimal cap thickness per patient did not change. In 68.5% of segments, plaque morphology did not change. Favourable change was observed in 18.4% of segments and unfavourable in 12.9%. There were no robust clinical predictors of change in plaque morphology. Attenuation analysis supported the qualitative characterisation, showing significantly different attenuation between different plaque types. Conclusions: In non-culprit coronary segments of patients with coronary artery disease under standard medical therapy, segment-level but not patient-level minimum fibrous cap thickness increases over time, with observations of both favourable and unfavourable changes in individual segments.