Effect of neointimal tissue morphology on vascular response to balloon angioplasty in lesions with in-stent restenosis after drug-eluting stent deployment: an optical coherence tomography analysis

Impact of acute coronary syndrome on early in-stent neoatherosclerosis as shown by optical coherence tomography

Background

Patients with acute coronary syndrome (ACS) have a higher risk of requiring target vessel revascularisation after percutaneous coronary intervention (PCI) than patients with stable angina. Neoatherosclerosis is a significant risk factor for very late stent thrombosis, and the presence of neoatherosclerosis is independently associated with major adverse cardiac events.

Aims

In this study, we used optical coherence tomography (OCT) to investigate the impact of ACS on neoatherosclerosis within 1 year after PCI.

Methods

We investigated 102 patients (122 lesions) who had undergone PCI using a second-generation drug-eluting stent (DES) from March 2017 to November 2020 and were followed up with OCT within 1 year. The patients were categorised into the ACS group or non-ACS group according to their clinical findings at the time of target lesion treatment. We used OCT to investigate the presence of neoatherosclerosis.

Results

The ACS group comprised 23 (22.5%) patients. There were no differences in the patients' clinical characteristics between the groups. The total stent length tended to be shorter in the ACS group than in the non-ACS group (24 mm vs 32 mm, respectively; p=0.09), but this difference was not statistically significant. The median duration from PCI was 290 days. Neoatherosclerosis was more frequent in ACS lesions (39% vs 4%; p<0.01), and implantation of a DES in ACS lesions was an independent predictor of neoatherosclerosis occurrence (odds ratio 9.70; p<0.01).

Conclusions

This observational study using OCT indicates that stenting for ACS lesions is associated with early in-stent neoatherosclerosis.

Relationship Between Optical Coherence Tomography-Derived In-Stent Neoatherosclerosis and the Extent of Lipid-Rich Neointima by Near-Infrared Spectroscopy and Intravascular Ultrasound: A Multimodal Imaging Study

Background In-stent restenosis, especially for neoatherosclerosis, is a major concern following percutaneous coronary intervention. This study aimed to elucidate the association of features of in-stent restenosis lesions revealed by optical coherence tomography (OCT)/optical frequency domain imaging (OFDI) and the extent of lipid-rich neointima (LRN) assessed by near-infrared spectroscopy (NIRS) and intravascular ultrasound, especially for neoatherosclerosis. Methods and Results We analyzed patients undergoing percutaneous coronary intervention for in-stent restenosis lesions using both OCT/OFDI and NIRS-intravascular ultrasound. OCT/OFDI-derived neoatherosclerosis was defined as lipid neointima. The existence of large LRN (defined as a long segment with 4-mm maximum lipid core burden index ≥400) was evaluated by NIRS. In 59 patients with 64 lesions, neoatherosclerosis and large LRN were observed in 17 (26.6%) and 21 lesions (32.8%), respectively. Naturally, large LRN showed higher 4-mm maximum lipid core burden index (median [interquartile range], 623 [518-805] versus 176 [0-524]; P<0.001). In OCT/OFDI findings, large LRN displayed lower minimal lumen area (0.9±0.4 versus 1.3±0.6 mm²; P=0.02) and greater max lipid arc (median [interquartile range], 272° [220°-360°] versus 193° [132°-247°]; P=0.004). In the receiver operating characteristic curve analysis, 4-mm maximum lipid core burden index was the best predictor for neoatherosclerosis, with a cutoff value of 405 (area under curve, 0.92 [95% CI, 0.83-1.00]). In multivariable logistic analysis, only low-density lipoprotein cholesterol (odds ratio, 1.52 [95% CI, 1.11-2.08]) was an independent predictor for large LRNs. Conclusions NIRS-derived large LRN was significantly associated with neoatherosclerosis by OCT/OFDI. The neointimal characterization by NIRS-intravascular ultrasound has potential as an alternative method of OCT/OFDI for in-stent restenosis lesions.

In Stent Neo-Atherosclerosis: Pathophysiology, Clinical Implications, Prevention, and Therapeutic Approaches

Despite the dramatic improvements of revascularization therapies occurring in the past decades, a relevant percentage of patients treated with percutaneous coronary intervention (PCI) still develops stent failure due to neo-atherosclerosis (NA). This histopathological phenomenon following stent implantation represents the substrate for late in-stent restenosis (ISR) and late stent thrombosis (ST), with a significant impact on patient’s long-term clinical outcomes. This appears even more remarkable in the setting of drug-eluting stent implantation, where the substantial delay in vascular healing because of the released anti-proliferative agents might increase the occurrence of this complication. Since the underlying pathophysiological mechanisms of NA diverge from native atherosclerosis and early ISR, intra-coronary imaging techniques are crucial for its early detection, providing a proper in vivo assessment of both neo-intimal plaque composition and peri-strut structures. Furthermore, different strategies for NA prevention and treatment have been proposed, including tailored pharmacological therapies as well as specific invasive tools. Considering the increasing population undergoing PCI with drug-eluting stents (DES), this review aims to provide an updated overview of the most recent evidence regarding NA, discussing pathophysiology, contemporary intravascular imaging techniques, and well-established and experimental invasive and pharmacological treatment strategies.

Diagnostic accuracy of optical coherence tomography for the identification of in-stent fibroatheroma following stent implantation: an ex vivo histological validation study

The accurate identification of in-stent fibroatheroma by in vivo imaging is clinically important to preventing the late catch-up phenomenon after stent deployment. This study investigated the diagnostic accuracy of optical coherence tomography (OCT) for the detection of "in-stent fibroatheroma" following stent implantation. Fifty stented coronary arteries from the 31 autopsy hearts were examined to compare OCT and histological image findings. A histological in-stent fibroatheroma was defined as a neointima containing an acellular necrotic core generated by macrophage infiltration. OCT-derived in-stent fibroatheroma comprised a heterogeneous pattern with an invisible stent strut behind the low-signal-intensity region. A total of 122 matched OCT and histology cross-sections were evaluated. Using histological findings as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value for OCT-derived in-stent fibroatheroma were 100%, 99%, 80%, and 100%, respectively. The only histological finding underlying the false-positive diagnosis of OCT-derived in-stent fibroatheroma was foam cell accumulation without a necrotic core on the neointimal surface. No false-negative diagnosis of OCT for in-stent fibroatheroma was apparent in this analysis. This study demonstrated the potential capability of OCT based on stent strut visualization behind low-signal-intensity regions to discriminate in-stent fibroatheroma from other neointimal tissues.