Qualitative and quantitative neointimal characterization by optical coherence tomography in patients presenting with in-stent restenosis

Association of the monocytes to high-density lipoprotein cholesterol ratio with in-stent neoatherosclerosis and plaque vulnerability: An optical coherence tomography study

BACKGROUND

Monocyte-to-high-density lipoprotein cholesterol ratio (MHR) is an independent predictor of atherosclerosis and in-stent restenosis (ISR). However, the association between MHR and the incidence of in-stent neoatherosclerosis (ISNA) remains to be validated.

METHODS

This study included 216 patients with acute coronary syndrome who had 220 ISR lesions and had undergone optical coherence tomography (OCT). All eligible patients were divided into three groups according to their MHR tertile level. OCT characteristics were comparatively analyzed between groups of different MHR levels, and univariate and multivariate logistic regression analyses were constructed to assess correlations between MHR level and ISNA as well as in-stent thin-cap fibroatheroma (TCFA). A receiver operating characteristic curve was used to determine the optimal MHR thresholds for predicting ISNA and in-stent TCFA.

RESULTS

The incidence of ISNA (70.3% vs. 61.1% vs. 20.3%, P < 0.001) and in-stent TCFA (40.5% vs. 31.9% vs. 6.8%, P < 0.001) was the highest in the third tertile, followed by the second and first tertiles, respectively. Multivariate analysis revealed that MHR was independently associated with ISNA (odds ratio [OR], 7.212; 95% confidence interval [CI], 1.287-40.416; P = 0.025) and in-stent TCFA (OR, 5.610; 95% CI, 1.743-18.051; P = 0.004) after adjusting for other clinical factors. The area under the curve was 0.745 (95% CI, 0.678-0.811; P < 0.001) for the prediction of ISNA and 0.718 (95% CI, 0.637-0.778; P < 0.001) for the prediction of in-stent TCFA.

CONCLUSION

MHR levels are an independent risk factor for ISNA.

Association Between Serum Uric Acid Levels and Neoatherosclerosis

Neoatherosclerosis is a major cause of stent failure after percutaneous coronary intervention. Metabolism such as hyperuricemia is associated with in-stent restenosis (ISR). However, the association between serum uric acid (sUA) levels and in-stent neoatherosclerosis (ISNA) has never been validated.A total of 216 patients with 220 ISR lesions who had undergone optical coherence tomography (OCT) of culprit stents were included in this study. According to their sUA levels, eligible patients were divided into two groups [normal-sUA group: sUA < 7 mg/dL, n = 126, and high-sUA group: sUA ≥ 7 mg/dL, n = 90]. OCT findings were analyzed and compared between the normal- and high-sUA groups.The incidence of ISNA (63.0% versus 43.0%, P = 0.004) was significantly higher in the high-sUA group than in the normal-sUA group. Lipid plaques (66.3% versus 43.0%, P < 0.001) and thin-cap fibroatheroma (38.0% versus 18.0%, P = 0.001) were observed more frequently in the restenotic tissue structure in patients in the high-sUA group than in those in the normal-sUA group. Meanwhile, univariate (OR: 1.208, 95% CI: 1.037-1.407; P = 0.015) and multivariate (OR: 1.254, 95% CI: 1.048-1.501; P = 0.013) logistic regression analyses indicated that sUA levels were an independent risk factor for ISNA after adjusting for relevant risk factors.The high-sUA levels were an independent risk factor for the occurrence of neoatherosclerosis in patients with ISR via OCT.

Optical Coherence Tomography Findings in Patients Presenting With In-Stent Restenosis: A Prospective Observational Study of Patterns of Neointimal Hyperplasia and Associated Risk Factors

Introduction Morphological features of neointimal tissue play a pivotal role in the pathophysiology of in-stent restenosis (ISR) after percutaneous coronary intervention (PCI). This study was designed to qualitatively and quantitatively assess neointimal characteristics of lesions using optical coherence tomography (OCT) in patients presenting with ISR.  Methods This was a single-center, prospective, observational study performed at a tertiary-care center in India. Patients diagnosed with stable angina and acute coronary syndrome with post-procedural angiographically documented restenosis (>50%) were included. Results A total of 34 patients with ISR were studied. Neointimal hyperplasia was classified as (i) homogenous group (n = 18) and (ii) non-homogenous group (n = 16). Fourteen (77.8%) diabetics belonged to the homogenous group. Predominant plaque characteristics such as neoatherosclerosis, cholesterol crystals, and calcium were documented in 14 (77.8%), 12 (66.7%), and 11 (61.1%) patients in the homogenous group and 10 (62.5%), 10 (62.5%), and 9 (56.2%) patients in the non-homogenous group, respectively. Unexpanded stent struts were identified in 11 (61.1%) and 11 (68.8%) patients in the homogenous and non-homogenous groups, respectively. Mean strut thickness was 93.73 ± 31.03 µm and 83.54 ± 18.0 µm, ISR was 72.50 ± 15.93% and 65.37 ± 21.69%, the neointimal thickness was 588.06 ± 167.82 μm and 666.25 ± 218.05 μm, and neointimal hyperplasia was 54.54 ± 11.23% and 59.26 ± 8.86% in the homogenous and non-homogenous groups, respectively. Conclusion Neoatherosclerosis and stent underexpansion were predominantly observed in our study and only diabetes was found to be significantly associated with homogenous neointimal hyperplasia.

Intravascular imaging in coronary stent restenosis: Prevention, characterization, and management

Despite the introduction of drug-eluting stents to combat the neointimal hyperplasia that occurred after BMS implantation, in-stent restenosis is still encountered in a significant number of patients, particularly as increasingly complex lesions are tackled by percutaneous coronary intervention. Many biological and mechanical factors interplay to produce restenosis, some of which are avoidable. Intravascular imaging provided unique insights into various forms of stent-related mechanical issues that contribute to this phenomenon. From a practical perspective, intravascular imaging can therefore help to optimize the stenting procedure to avert these issues. Moreover, once the problem of restenosis eventuates, imaging can guide the management by tackling the underlying identified mechanism. Finally, it can be used to evaluate the re-intervention results. Nevertheless, with the emergence of different treatment options, more evidence is needed to define patient/lesion-specific characteristics that may help to tailor treatment selection in a way that improves clinical outcomes.

Periprocedural myocardial injury according to optical characteristics of neointima and treatment modality of in-stent restenosis

Aims

Aim of the present study was to investigate the impact of increasing neointimal inhomogeneity and neoatherosclerosis as well as of treatment modality of in-stent restenosis (ISR) on the occurrence of periprocedural myocardial injury (PMI).

Methods and results

Patients with normal or stable/falling increased baseline high-sensitivity troponin T (hs-cTnT) undergoing intravascular optical coherence tomography (OCT) and subsequent percutaneous coronary intervention (PCI) of ISR by means of drug-coated balloon (DCB) or drug-eluting stent (DES) were included. Overall, 128 patients were subdivided into low (n = 64) and high (n = 64) inhomogeneity groups, based on the median of distribution of non-homogeneous quadrants. No significant between-group differences were detected in terms of hs-cTnT changes (28.0 [12.0–65.8] vs. 25.5 [9.8–65.0] ng/L; p = 0.355), or the incidence of major PMI (31.2 vs. 31.2%; p = 1.000). Similarly, no differences were observed between DCB- and DES-treated groups in terms of hs-cTn changes (27.0 [10.0–64.0] vs. 28.0 [11.0–73.0] ng/L; p = 0.795), or the incidence of major PMI (28.9 vs. 35.6%; p = 0.566). Additionally, no significant interaction was present between optical neointimal characteristics and treatment modality in terms of changes in hs-cTnT (P_int = 0.432). No significant differences in PMI occurrence were observed between low and high neoatherosclerosis subgroups.

Conclusions

In patients undergoing PCI for ISR, there was no association between increasing neointimal inhomogeneity, or increasing expression of neoatherosclerotic changes and occurrence of PMI. PMI occurrence was not influenced by the treatment modality (DCB vs. DES) of ISR lesions, a finding that supports the safety of DCB treatment for ISR.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-022-02024-z.

Clinical outcomes by optical characteristics of neointima and treatment modality in patients with coronary in-stent restenosis

BACKGROUND

Drug-coated balloons (DCB) and drug-eluting stents (DES) represent the currently recommended treatments for in-stent restenosis (ISR). Optical coherence tomography (OCT) allows detailed neointimal characterisation which can guide treatment strategies.

AIMS

The aims of this study were first, to assess the relation between neointimal pattern and clinical outcomes following in-stent restenosis (ISR) treatment, and second, to explore a potential interaction between neointimal pattern and treatment modality relative to clinical outcomes.

METHODS

Patients undergoing OCT-guided treatment (DCB or DES) of ISR in three European centres were included. Based on the median of distribution of non-homogeneous neointima quadrants, patients were categorised into low and high inhomogeneity groups.

RESULTS

A total of 197 patients (low inhomogeneity=100 and high inhomogeneity=97) were included. There were no significant differences in terms of major adverse cardiac events (MACE) (p=0.939) or target lesion revascularisation (TLR) (p=0.732) between the two groups. The exploratory analysis showed a significant interaction between neointimal pattern and treatment modality regarding MACE (pint=0.006) and TLR (pint=0.022). DES showed a significant advantage over DCB in the high (MACE: HR 0.26 [0.10-0.65], p=0.004; TLR: HR 0.28 [0.11-0.69], p=0.006), but not in the low inhomogeneity group (MACE: p=0.917; TLR: p=0.797).

CONCLUSIONS

In patients with ISR treated with DCB or DES, there were no significant differences in terms of MACE or TLR between the low and high inhomogeneity groups. A significant interaction was observed between treatment modality and neointimal pattern with an advantage of DES over DCB in the high and no difference in the low inhomogeneity group. This warrants confirmation from prospective dedicated studies.

Results of paclitaxel-drug-coated balloons (Pantera Lux) for coronary in-stent restenosis: Italian experience from REGistry of Paclitaxel Eluting Balloon in ISR study

AIMS

Drug-eluting stent (DES) implantation is an effective treatment of in-stent restenosis (ISR). However, literature data indicate that drug-coated balloons (DCBs) may be a valid alternative, particularly for recurrent ISR. We sought to evaluate clinical results on the long-term efficacy of a new DCB for ISR treatment.

METHODS

One hundred and ninety-nine patients were treated with paclitaxel drug-coated balloons (Pantera Lux, Biotronik, Switzerland) in the Italian REGistry of Paclitaxel Eluting Balloon in ISR (REGPEB study). Clinical follow-up was scheduled at 1 and 12 months. A subgroup of patients received adjunctive 5-year follow-up. Primary end point was Major Adverse Cardiac Events (MACE) at 1 year.

RESULTS

A total of 214 ISR coronary lesions were treated (75.4% DES-ISR). Mean time between stent implantation and DCB treatment is 41 months. DCBs were successfully delivered in 99% of the cases; crossover to a DES occurred in 3% of cases. Procedural success rate was 98.5%. Clinical success rate was 98.5%. First-month follow-up compliance was 98% and freedom from MACE was 96.9%. Twelve-month follow-up compliance was 89.3% with a freedom from MACE rate of 87.3% (CI: 81.3-91.5%). Five-year long-term follow-up showed 65.2% of freedom from MACE.

CONCLUSION

Our study confirms that Pantera Lux treatment is effective and well tolerated in ISR, showing good acute and long/very long-term results in the treatment of complex lesions (DES and late ISR).

Validation and application of OCT tissue attenuation index for the detection of neointimal foam cells

Neointimal infiltration with foamy macrophages is recognized as an early and important sign of de-novo atherosclerosis after stent implantation (neoatherosclerosis). Recent histopathological studies have proven that automated quantification of signal attenuation using intravascular optical coherence tomography (OCT) imaging allows for sensitive identification of macrophages in native atherosclerotic disease. Whether this is true for neointimal foam cells in the setting of neoatherosclerosis remains unknown. Autopsy samples of stented coronary arteries (n = 13 cases) were evaluated by histology and OCT. After co-registration with histology, the attenuation rate of emitted laser light was measured in regions with and without neointimal foamy macrophages relative to its peak intensity at the blood-tissue interface. Attenuation index was subsequently determined as slope of a regression curve fitted to individual data points. Receiver operating curve (ROC) analysis was used to establish an optimal cut-off for detecting foamy macrophages in homogenous and non-homogenous neointima, respectively. Finally, the tissue attenuation index was applied to confirm or exclude the presence of neointimal foamy macrophages in symptomatic patients presenting with in-stent restenosis and undergoing intravascular OCT imaging (n = 29 cases). Tissue attenuation index derived from post-mortem samples differed significantly between histologically confirmed regions with and without neointimal foamy macrophages (− 1.23 ± 1.42 vs. − 0.52 ± 1.79, p < 0.05). ROC analysis was able to distinguish neointima with foamy macrophage infiltration from neointima without (93% sensitivity, 73% specificity, cut-off − 0.79, AUC 0.87 for homogenous neointima and 40% sensitivity, 95% specificity, cut-off − 1.93, AUC 0.69 for non-homogenous neointima). In symptomatic patients presenting with in-stent restenosis after stent implantation and undergoing intravascular imaging with OCT, neointimal foamy macrophages were detected in 34.2% of homogenous and 43.6% of non-homogenous neointimal ROI’s evaluated. OCT-derived and histopathologically validated tissue attenuation index enables identification of neointimal foamy macrophages in stented coronary arteries. Such image-based post-processing software algorithm may help discern and triage subjects at increased risk for device-related events.

Clinical Outcomes of Drug-Eluting versus Bare-Metal In-Stent Restenosis after the Treatment of Drug-Eluting Stent or Drug-Eluting Balloon: A Systematic Review and Meta-Analysis

Background

Although drug-eluting stents (DES) have reduced the rates of in-stent restenosis (ISR) compared with bare-metal stents (BMS), DES related ISR (DES-ISR) still occurs and outcomes of DES-ISR remain unclear. The objective of this meta-analysis was to investigate the long-term clinical outcomes of patients with DES-ISR compared with patients with BMS related ISR (BMS-ISR) after the treatment of DES or drug-eluting balloon (DEB). Methods and results. We searched the literature in the main electronic databases including PUBMED, EMBASE, Cochrane Library, and Web of Science. The primary endpoints were target lesion revascularization (TLR) and target vessel revascularization (TVR). The secondary endpoints included all cause death (ACD), cardiac death (CD), myocardial infarction (MI), stent thrombosis or re-in-stent restenosis (ST/RE-ISR), and major adverse cardiovascular events (MACEs). A total of 19 studies with 6256 participants were finally included in this meta-analysis. Results showed that the rates of TLR (P < 0.00001), TVR (P < 0.00001), CD (P=0.02), ST/RE-ISR (P < 0.00001), and MACEs (P < 0.00001) were significantly higher in the DES-ISR group than in the BMS-ISR group. No significant differences were found between the two groups in the rates of MI (P=0.05) and ACD (P=0.21).

Conclusions

Our study demonstrated that patients with DES-ISR had worse clinical outcomes at the long-term follow-up than patients with BMS-ISR after the treatment of DES or DEB, suggesting that DES and DEB may be more effective for BMS-ISR than that for DES-ISR. Positive prevention of DES-ISR is indispensable and further studies concentrating on detecting the predictors of outcomes of DES-ISR are required.

Are we curing one evil with another? A translational approach targeting the role of neoatherosclerosis in late stent failure

Neoatherosclerosis is defined as foamy macrophage infiltration into the peri-strut or neointimal area after stent implantation, potentially leading to late stent failure through progressive atherosclerotic changes including calcification, fibroatheroma, thin-cap fibroatheroma, and rupture with stent thrombosis (ST) in advanced stages. Human autopsy as well as intravascular imaging studies have led to the understanding of neoatherosclerosis formation as a similar but significantly accelerated pathophysiology as compared to native atherosclerosis. This acceleration is mainly based on disrupted endothelial integrity with insufficient barrier function and augmented transmigration of lipids following vascular injury after coronary intervention and especially after implantation of drug-eluting stents. In this review, we summarize translational insights into disease pathophysiology and discuss therapeutic approaches to tackle this novel disease entity. We introduce a novel animal model of neoatherosclerosis alongside accompanying in vitro experiments, which show impaired endothelial integrity causing increased permeability for low-density lipoprotein cholesterol resulting in foam cell transformation of human monocytes. In addition, we discuss novel intravascular imaging surrogates to improve reliable diagnosis of early stage neoatherosclerosis. Finally, a therapeutic approach to prevent in-stent neoatherosclerosis with magnesium-based bioresorbable scaffolds and systemic statin treatment demonstrated the potential to improve arterial healing and re-endothelialization, leading to significantly mitigated neoatherosclerosis formation in an animal model of neoatherosclerosis.