The relationship among extent of lipid-rich plaque, factors associated with a reduction of lipid-rich plaque and late lumen loss: a near-infrared spectroscopy and intravascular ultrasound study
Authors: Takahashi N , Dohi T , Endo H , Nishio R , Fukase T , Takeuchi M , Doi S , Kato Y , Okai I , Iwata H , Okazaki S , Isoda K , Miyauchi K , Daida H , Minamino T 
Published: October 2021

Abstract

Background
Near-infrared spectroscopy (NIRS) and intravascular ultrasound (IVUS) are useful imaging modalities to identify lipid-rich plaque (LRP) which is associated with an increased risk of future cardiovascular events in individuals undergoing PCI. Pathological studies have raised concerns that treating LRP with stents may impair vascular healing. However, the impact of stent implantation to LRP lesions was less known. Moreover, little information is available about changes in the extent of LRP at before and after PCI.

Purpose
The aim of this study was to investigate changes in LRP by NIRS between pre- and post-stent implantation, and to evaluate an association among impact of LRP by NIRS at pre- and post-stenting and late lumen loss (LLL) by angiography.

Methods
We studied 175 lesions in 149 patients who underwent PCI under NIRS-IVUS guidance and follow-up angiography at 8-month later from 2017 to 2020. Plaque characteristics on IVUS, the extent of LRP [defined as a long segment with a 4-mm maximum lipid core burden index (maxLCBI4mm)] on NIRS, and quantitative coronary angiography measurements were analyzed. We evaluated a change of the extent of LRP between pre- and post-stenting at index PCI procedure, and association between the extent of LRP and a 8-month LLL at follow-up coronary angiography. A large LRP was defined as maxLCBI4mm&gt;400 at pre-stenting.

Results
Mean age was 64.5 years old, and 123 (82%) patients were male. The prevalence of large LRP was 51% and median plaque burden at minimum lumen area was 81%. The extent of LRP at culprit lesion significantly decreased from pre- to post-stenting (median maxLCBI4mm [interquartile range (IQR)]: 407 [199, 580] to 133 [13, 319], p&lt;0.001) (Figure 1). In multivariable liner regression analysis, independent predictors for the reduction of LRP were a pre-stenting LRP (β coefficient = −57.0, 95% confidence interval (CI) [−65.1 to −48.8], p&lt;0.001) and plaque burden (β coefficient = −30.0, 95% CI [−56.6 to −3.4], p&lt;0.001), respectively. On the other hands, patient comorbidities, lipid profile and inflammatory markers were not associated with the reduction of LRP (all p&gt;0.05). Median LLL at follow-up angiogram was 0.17 [0.07–0.35] mm. Both the extent of pre- and post-stenting LRP were not associated with LLL (r=0.018, p=0.80 and r=0.022, p=0.76, respectively) (Figure 2). In addition, there was no significant difference in LLL between the post-stenting large and non-large LRP (median [IQR] 0.18 [0.08–0.35] vs. 0.17 [0.07–0.35]; P=0.95).

Conclusions
This study showed coronary stent implantation significantly reduced the NIRS-derived LRP in patients undergoing PCI. Although the extent of pre-stenting LRP and IVUS plaque burden predicted the reduction of LRP, the extent of pre- and post-stenting LRP were not associated with LLL. These findings suggest that stent implantation for LRP, even in a large LRP, is safe and does not affect LLL.

Funding Acknowledgement
Type of funding sources: None. Figure 1. Scatter plotsFigure 2. CENTRAL Figure