Association between lipid-rich plaques and thrombus formation after excimer laser coronary angioplasty in in-stent restenosis and de novo lesions

Excimer laser coronary angioplasty (ELCA) in percutaneous coronary intervention (PCI) is safe and effective. However, thrombotic complications after ELCA occasionally occur. This study aimed to evaluate the impact of lipid-rich plaque in both in-stent restenosis (ISR) and de novo lesions on thrombus formation and transient no-reflow after ELCA. We conducted a single-center, retrospective, observational study including 27 lesions in 26 patients who underwent PCI with ELCA. Optical coherence tomography (OCT) was performed on all lesions before and immediately after ELCA. We measured the lipid angle per millimeter and lipid length of plaques with signal attenuation. We also recorded ELCA-induced thrombus formation and transient no-reflow. Thrombus formation and transient no-reflow were observed in nine (33%) and four lesions (15%), respectively. The frequency of ISR was significantly higher in the no-thrombus group than in the thrombus group. ISR lesions had a significantly lower lipid index (median [interquartile range] 108° [0°–756°] vs. 2541° [1205°–4336°]; p = 0.004) than de novo lesions. Among ISR lesions, those with ELCA-induced thrombus formation had a significantly higher lipid index (1370° [756°–4992°] vs. 29° [0°–285°]; p = 0.01) and significantly longer lipid length (8 mm [7–24 mm] vs. 0.5 mm [0–2.5 mm]; p = 0.01). The findings suggest that thrombus formation was more frequently observed in de novo lesions than in ISR lesions. OCT-detected lipid-rich plaques in ISR lesions were strongly associated with thrombus formation following ELCA.