2017 September	The patient was admitted to our hospital with unstable angina pectoris. After primary percutaneous coronary intervention (PCI) for culprit lesion, coronary angiogram showed the presence of a non-obstructive stenotic lesion in the left main trunk artery (LMT). Near-infrared spectroscopy–intravascular ultrasound (NIRS–IVUS) and optical coherence tomographic (OCT) imaging showed that the non-obstructive stenotic lesion in the LMT had lipid-rich vulnerable plaque with a thin cap and a high lipid core burden index (LCBI), which could trigger lesion-related, fatal cardiac events. We treated this lesion using aggressive lipid-lowering therapy.
2017 December	Low density lipoprotein cholesterol significantly decreased to 14 mg/dL (91% reduction from index PCI). However, the NIRS–IVUS and OCT imaging findings did not show remarkable changes in non-obstructive stenotic lesion. The maximum LCBI4mm (max LCBI4mm) value decreased from 422 to 417.
2018 May	The OCT imaging showed that the fibrous cap increased in size from 50 µm to 100 µm. However, the decrease in the max LCBI4mm value was insufficient and was limited to 318.
2019 September	We continued serial observation of this lesion for up to 12 months and 24 months, respectively. The grayscale IVUS imaging showed no remarkable changes were seen in the attenuation angle, which is an indicator of the lipid core. We detected the stepwise decrease in the max LCBI4mm value during long-term follow-up. At last follow-up, the clinical course was uneventful.