Intravascular Imaging for Guiding In-Stent Restenosis and Stent Thrombosis Therapy

Advances in stent technology and the design of endovascular devices with thinner struts, anti-inflammatory and antithrombotic polymers, and better drug kinetics have enhanced the safety and efficacy of the second-generation drug-eluting stents and broadened their use in the therapy of high-risk patients and complex anatomies. However, despite these developments, in-stent restenosis and stent thrombosis remain the Achilles' heel of percutaneous coronary intervention, with their cumulative incidence reaching up to 10% at 5 years following percutaneous coronary intervention. The treatment of stent failure poses challenges and is associated with a worse prognosis than conventional percutaneous coronary intervention. Several studies have recently highlighted the value of intravascular imaging in identifying causes of stent failure, underscored its role in treatment planning, and registries have shown that its use may be associated with better clinical outcomes. The present review aims to summarize the evidence in the field; it discusses the value of intravascular imaging in identifying the mechanisms of in-stent restenosis and stent thrombosis in assessing the morphological characteristics of neointima tissue that appears to determine long-term outcomes in evaluating procedural results, and presents the findings of studies supporting its value in guiding therapy in stent failure.

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.

Management of in-stent restenosis

In-stent restenosis (ISR) remains the most common cause of stent failure after percutaneous coronary intervention (PCI). Recent data suggest that ISR-PCI accounts for 5-10% of all PCI procedures performed in current clinical practice. This State-of-the-Art review will primarily focus on the management of ISR but will begin by briefly discussing diagnosis and classification. We then move on to detail the evidence base underpinning the various therapeutic strategies for ISR before finishing with a proposed ISR management algorithm based on current scientific data.

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.

Predictors and outcomes of neoatherosclerosis in patients with in-stent restenosis

BACKGROUND

In-stent restenosis (ISR), especially for neoatherosclerosis, is still a major problem of percutaneous coronary intervention (PCI) even in the drug-eluting stent (DES) era.

AIMS

The purpose of this study was to investigate the impact of neoatherosclerosis on prognosis after PCI for ISR.

METHODS

Between March 2009 and December 2017, 313 ISR lesions in patients undergoing an OCT-guided PCI in five hospitals were retrospectively enrolled. Neoatherosclerosis was defined as a lipid neointima or calcified neointima. We examined the association between neoatherosclerosis and the clinically driven target lesion revascularisation (CD-TLR) rates.

RESULTS

In 313 ISR lesions, 64 lesions (20.4%) had bare metal stents and 241 lesions (77.0%) had drug-eluting stents (DES). Among them, 47.0% of lesions (147 lesions) had neoatherosclerosis. A multivariate logistic regression analysis demonstrated that eGFR (odds ratio [OR] 0.986, 95% confidence interval [CI]: 0.974-0.998; p=0.023), the time from PCI to the ISR (OR 1.13, 95% CI: 1.06-1.22; p<0.001) and DES-ISR (OR 2.48, 95% CI: 1.18-5.43; p=0.019) were independent predictors for neoatherosclerosis. A multivariate regression analysis demonstrated that neoatherosclerosis was an independent predictor of CD-TLR.

CONCLUSIONS

In this multicentre ISR registry, OCT imaging demonstrated that eGFR, the time from PCI to the ISR and DES-ISR were independent predictors for neoatherosclerosis and that neoatherosclerosis in ISR lesions had a worse impact on the CD-TLR rate.

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.

Association between in-stent neointimal characteristics and native coronary artery disease progression

Background and aims

The prognosis of stented lesions differs according to in-stent neointimal characteristics on optical coherence tomography (OCT). In particular, patients who show in-stent heterogeneous neointima are associated with a higher incidence of target lesion revascularization (TLR) compared with those who show in-stent non-heterogeneous neointima. However, the relationship between in-stent neointimal characteristics and native coronary atherosclerosis progression has not been clearly elucidated. The study aimed to investigate the relationship between in-stent neointimal characteristics and progression of native atherosclerosis.

Methods

The neointimal characteristics of 377 patients with 377 drug-eluting stents (DESs) were quantitatively and qualitatively assessed using OCT. The OCT-based neointima was categorized as homogeneous (n = 207), heterogeneous (n = 93), and layered (n = 77). The relationship of non-target lesion revascularization (non-TLR) with neointimal characteristics was evaluated after OCT examination of the stents.

Results

After a median follow-up duration of 40.0 months, patients with heterogeneous neointima showed significantly higher non-TLR rates than those with homogeneous neointima and tended to have higher non-TLR rates than those with layered neointima (heterogeneous vs. homogeneous:14.0% vs. 8.7%, p = 0.046; heterogeneous vs. layered neointima:14.0% vs. 7.8%, p = 0.152). Multivariate analysis showed that the independent determinants for non-TLR were heterogeneous neointima (HR: 2.237, 95% CI: 1.023–4.890, p = 0.044) and chronic kidney disease (hazard ratio [HR]: 8.730, 95% CI: 2.175–35.036, p = 0.002).

Conclusions

The heterogeneous neointima in DES-treated lesions was associated with a higher incidence of non-TLR and target lesion failure. This finding suggests that the neointimal pattern may reflect the progression of the native lesion.

Multi-modality intravascular imaging for guiding coronary intervention and assessing coronary atheroma: the Novasight Hybrid IVUS-OCT system

Intravascular imaging has evolved alongside interventional cardiology as an adjunctive tool for assessing plaque pathology and for guiding and optimising percutaneous coronary intervention (PCI) in challenging lesions. The two modalities which have dominated the field are intravascular ultrasound (IVUS), which relies on sound waves and optical coherence tomography (OCT), relying on light waves. These approaches however have limited efficacy in assessing plaque morphology and vulnerability that are essential for guiding PCI in complex lesions and identifying patient at risk that will benefit from emerging therapies targeting plaque evolution. These limitations are complementary and, in this context, it has been recognised and demonstrated in multi-modality studies that the concurrent use of IVUS and OCT can help overcome these deficits enabling a more complete and accurate plaque assessment. The Conavi Novasight Hybrid IVUS-OCT catheter is the first commercially available device that is capable of invasive clinical coronary assessment with simultaneously acquired and co-registered IVUS and OCT imaging. It represents a significant evolution in the field and is expected to have broad application in clinical practice and research. In this review article we present the limitations of standalone intravascular imaging techniques, summarise the data supporting the value of multimodality imaging in clinical practice and research, describe the Novasight Hybrid IVUS-OCT system and highlight the potential utility of this technology in coronary intervention and in the study of atherosclerosis.

Neointima characteristics as a prognostic marker for drug-coated balloon angioplasty in patients with in-stent restenosis: an optical coherence tomography study

BACKGROUND

Research has shown that the prognosis of in-stent restenosis (ISR) lesions after drug-coated balloon (DCB) angioplasty can differ in relation to in-stent neointimal characteristics. However, changes in neointima characteristics after DCB have not been studied. This study sought to investigate changes in neointima characteristics after DCB for ISR.

METHODS

From the Yonsei Optical Coherence Tomography (OCT) registry, data on DCBs performed in patients with ISR were collected. Neointima characteristics were categorized as homogeneous, heterogeneous, layered neointima, and neoatherosclerosis in each OCT procedure. Homogeneous and layered neointima were classified as a favorable neointima, while heterogeneous neointima and neoatherosclerosis were classified as an unfavorable neointima. The data of 67 ISR patients were analyzed.

RESULTS

The median duration between initial and follow-up OCT was 9.6 months. Patients with homogeneous and layered neointima on the initial OCT before DCB mostly appeared as homogeneous (66.7 and 68.2%, respectively) on the follow-up OCT, whereas most of the patients with heterogeneous neointima on the initial OCT remained unaltered (70%). Patients with unfavorable neointima at either the initial (P = 0.023) or the follow-up OCT (P = 0.037) had a worse major adverse cardiovascular event-free survival than the other patients. Patients who showed unfavorable neointima at both the initial and the follow-up OCT had the worst event-free survival (P = 0.038).

CONCLUSIONS

The follow-up OCT neointimal characteristics after DCB for ISR was associated with initial OCT characteristics. Sustained unfavorable neointima in serial OCT imaging may reflect poor prognosis in patients with ISR treated with DCB.

Influence of neoatherosclerosis on prognosis and treatment response in patients with in-stent restenosis

INTRODUCTION AND OBJECTIVES

Neoatherosclerosis is one of the causes of in-stent restenosis (ISR). Our objective was to evaluate the influence of neoatherosclerosis on prognosis and treatment response in patients with ISR.

METHODS

This is a pooled analysis of the optical coherence tomography (OCT)-substudies of 2 multicenter, randomized clinical trials, RIBS IV and V, comparing treatment with paclitaxel-coated balloon vs everolimus-eluting stent in patients with ISR. OCT evaluation was performed at baseline and at 6 to 9 months. Neoatherosclerosis was defined in baseline OCT as neointima with calcified or lipid content. We evaluated the angiographic and OCT results at 6 to 9 months and the occurrence of major adverse cardiovascular events at 3 years of follow-up in patients with and without neoatherosclerosis treated with paclitaxel-coated balloon or everolimus-eluting stents.

RESULTS

Sixty-four patients underwent OCT at the time of the index procedure. Neoatherosclerosis was documented in 23 (36%) lesions. Angiographic follow-up at 6 to 9 months showed no differences in restenosis [5 (24%) vs 6 (15%) P=.49], minimum lumen diameter (1.79±0.7 vs 1.94±0.6mm; P=.41) or late loss (0.33±0.7 vs 0.15±0.5; P=.34) in patients with and without neoatherosclerosis, respectively. Follow-up OCT confirmed the absence of differences in quantitative parameters and the characteristics of tissue coverage between the 2 groups. At 3 years of follow-up, the major adverse cardiovascular events rate was 3 (13%) vs 5 (12%) in the neoatherosclerosis and nonneoatherosclerosis groups (HR, 0.94; 95%CI, 0.22-3.93; P=.93).

CONCLUSIONS

In this limited study population, OCT-defined neoatherosclerosis did not seem to influence acute and long-term outcomes in patients randomized to paclitaxel-coated balloon or everolimus-eluting stents for ISR.

Efficacy of drug-coated balloon angioplasty in early versus late occurring drug-eluting stent restenosis: A pooled analysis from the randomized ISAR DESIRE 3 and DESIRE 4 trials

BACKGROUND

Whether there exist differences concerning clinical outcomes between patients presenting with early versus late DES-ISR undergoing treatment with drug-coated balloons (DCB) remains a scientific knowledge gap.

METHODS

This is a pooled analysis including patients with DES-ISR assigned to treatment with DCB in the setting of the ISAR DESIRE 3 and 4 trials. Clinical outcomes were evaluated according to time of occurrence of ISR after DES implantation, in patients presenting with early (≤12 months) versus late DES-ISR (>12 months) undergoing treatment with DCB. The primary endpoint of this analysis was major adverse cardiac event (MACE), defined as the combined incidence of death, myocardial infarction and target lesion revascularization (TLR) at 12 months after DCB treatment. Secondary endpoints included the incidence of death, myocardial infarction, TLR and target lesion thrombosis at 12 months after DCB treatment.

RESULTS

This analysis included 352 patients, 199 patients presented with early-ISR, 153 patients with late-ISR. Concerning the primary endpoint, patients with early-DES-ISR as compared those with late-DES-ISR showed significant higher risk (25.9% vs. 17.0%; p = .04). In a multivariate analysis including diabetic status, clinical presentation, previous coronary bypass graft and diameter stenosis after DCB-treatment, the adjusted hazard ratio showed significant higher risk for MACE of early-DES-ISR as compared to late-DES-ISR (HR_adj = 1.8, [95% CI = 1.1-3.0], p = .02).

CONCLUSION

Clinical outcome at 12 months after treatment of DES-ISR with DCB, showed significant higher clinical event rates in patients presenting with early DES restenosis, as compared with patients presenting with late DES restenosis.

Failure of drug-coated balloon angioplasty to treat bare metal in-stent restenosis accompanied by late stent thrombosis but successful treatment of binary in-stent restenosis

Drug-coated balloons (DCB) are effective in treating in-stent restenosis (ISR) with neointimal proliferation after bare-metal stent (BMS) implantation, but it is unclear whether DCB are effective in treating BMS-ISR accompanied by thrombosis. An 84-year-old man with previous inferior myocardial infarction and atrial fibrillation developed acute myocardial infarction (AMI) during hospitalization for intracerebral hemorrhage. Emergent coronary angiography (CAG) revealed severe stenosis of the distal left circumflex coronary artery. We implanted a BMS to avoid long-term triple antithrombotic therapy. He received aspirin, clopidogrel, and rivaroxaban for 1 month and then received clopidogrel and rivaroxaban. Seventy days after BMS implantation, he developed AMI, and emergent CAG revealed occlusion of the BMS due to late stent thrombosis. After thrombus aspiration, intravascular ultrasound showed incomplete neointimal healing in the proximal portion of the stent and excessive neointimal proliferation in the distal portion of the stent. DCB angioplasty of the entire BMS was performed after scoring balloon pre-dilation. Seven months after BMS implantation, follow-up CAG revealed binary ISR. DCB angioplasty of the entire BMS was performed again after scoring balloon pre-dilation. Thirteen months after BMS implantation, follow-up CAG did not reveal recurrence of ISR. <Learning objective: Drug-coated balloons (DCB) were ineffective when there was excessive neointimal proliferation accompanied by thrombosis, but effective in binary in-stent restenosis (ISR). DCB may be ineffective in early ISR after bare-metal stent implantations and when there is excessive neointimal proliferation accompanied by thrombosis. Since the safety and efficacy of DCB to treat excessive neointimal proliferation occurring with late stent thrombosis is unclear, further studies are needed.>.

Clinical outcomes of rotational atherectomy in severely calcified in-stent restenosis: a single-center, retrospective study

Neointimal calcification after stent implantation has been reported as one of the forms of neoatherosclerosis. There are a few patients with in-stent restenosis (ISR) and an undilatable calcified neointima who require rotational atherectomy to achieve sufficient acute gain in lumen diameter. However, the clinical outcomes of rotational atherectomy for undilatable calcified ISR have not been fully elucidated. Therefore, we investigated the safety and efficacy of rotational atherectomy for treating calcified ISR. This retrospective study included 17 patients (20 lesions) who had undergone percutaneous coronary intervention including rotational atherectomy to treat ISR with severely calcified neointima. Kaplan-Meier analysis was used to analyze the data. The mean age of the enrolled patients was 67±18 years, and 71% were men. The patients had highly atherogenic characteristics: 65% had diabetes mellitus and 53% were receiving hemodialysis. Procedural success was obtained in 19 (95%) patients, and the acute gain in lumen diameter was acceptable (1.7±0.6 mm). However, during a median follow-up of 571 days, the incidences of major adverse cardiac and cerebrovascular events per patient and clinical-driven target lesion revascularizations per lesion were relatively high. There were no differences in clinical outcomes according to the baseline characteristics, type of restenotic stents, and therapeutic strategy. In conclusion, clinical outcomes of rotational atherectomy for severely calcified ISR were unfavorable despite a high success rate and acceptable acute gain in lumen diameter.

The impact of tissue characterization for in-stent restenosis with optical coherence tomography during excimer laser coronary angioplasty

We aimed to evaluate the impact of tissue characterization for in-stent restenosis (ISR) with optical computed tomography (OCT) during excimer laser coronary angioplasty (ELCA) in the drug-eluting stent (DES) era. The effect of ELCA for ISR according to differences in tissue characteristics is unclear. Fifty-three ISR lesions (7 bare metal stents and 46 drug-eluting stents) were treated with an ELCA catheter. After ELCA, balloon dilatation with either the scoring or non-compliant balloons was conducted. The procedure was completed by applying a drug-coated balloon. Tissue characterization and lumen measurement with OCT were performed thrice: (1) before percutaneous coronary intervention (PCI), (2) after ELCA, and (3) and after the procedure. Lesions were categorized into the homogenous, layered, and mixed groups. Follow-up angiograms were conducted 6-12 months after PCI. No significant differences in minimal lumen area (MLA) were observed before PCI. A significant difference was observed in MLA after ELCA among the three groups (homogeneous group: 1.75 ± 0.84 mm2, layered group: 1.72 ± 0.45 mm2, mixed group: 2.24 ± 0.70 mm2, P = 0.048). Final MLA was larger in the mixed group than in the homogeneous group (P = 0.028). No significant difference was observed in binary restenosis in the follow-up angiogram (homogeneous group 55.5%, layered group 33.3%, mixed group 33.3%; P = 0.311) and the target lesion revascularization rate (homogeneous 30.0%, layered 23.8%, mixed 25.0%; P = 0.923). Tissue characterization by OCT may predict the efficacy of ELCA and balloon angioplasty for ISR during the acute phase.

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

AIMS

To describe optical coherence tomography (OCT) findings in patients with in-stent restenosis (ISR) and determine predictors of neointimal patterns and neoatherosclerosis.

METHODS AND RESULTS

Patients undergoing OCT prior to PCI for ISR in three European centres were included. Analyses were performed in a core laboratory. Qualitative and quantitative [gray-scale signal intensity (GSI)] neointima analyses were performed on a per quadrant basis. A total of 107 patients were included. Predominantly homogeneous lesions included 4.5% (0.0-14.3) non-homogeneous quadrants, while predominantly non-homogeneous ones included 28.1% (20.3-37.5) homogeneous quadrants. Mean GSI values differed significantly between homogeneous [108.4 (92.5-123.6)], non-homogeneous [79.9 (61.2-95.9)], and neoatherosclerosis [88.3 (72.8-104.9)] quadrants (p < 0.001 for all comparisons). Stent underexpansion was observed in 48.5% and 61.1% of lesions, respectively (p = 0.225). Female sex and maximal neointimal thickness independently correlate with a non-homogeneous pattern, while angiographic pattern and diabetes mellitus inversely correlate with such pattern. Time from index stenting procedure was the only independent predictor of neoatherosclerosis.

CONCLUSIONS

Different neointimal patterns coexist in a significant proportion of ISR lesions. GSI values differ significantly between neointimal categories. Neoatherosclerosis is a time-dependent phenomenon, displaying different time courses in DES compared to BMS, with earlier appearance in the former group. Stent underexpansion is a frequent finding in patients with ISR.

Association Between TG-to-HDL-C Ratio and In-Stent Stenosis Under Optical Coherence Tomography Guidance

We determined the relevance between the TG-to-HDL-C ratio and stent restenosis. Ninety-nine patients with in-stent stenosis (ISR) who were admitted to An Zhen Hospital in Beijing between April 2014 and June 2017 were selected. At the same time, 122 patients with coronary stenosis <50% were selected. All patients were tested for TG, HDL-C, and TG/HDL-C ratio. Optical coherence tomography (OCT) can assess microscopic status in all ISR patients. The proportion of male and Diabetic patients were significantly higher for ISR. There were differences in the prevalence of cigarette smokers among the different tissue types, among which the layered tissue type accounted for the highest proportion. In logistic regression analysis the study showed that male, diabetes mellitus, and the TG/HDL-C ratio are risk factors for ISR. The ISR ROC was 0.725 based on the TG/HDL-C ratio diagnosis. It is related to the degree of coronary stenosis and effective in diagnosing in-stent stenosis in ISR.

Late lumen enlargement induced by drug coated balloon in the patient with PTFE-covered stent restenosis

We report a case of percutaneous coronary intervention with drug coated balloon (DCB) for the in-stent restenosis of polytetrafluoroethylene-covered stent. One year follow-up angiography was excellent and in-stent lumen enlargement compared with the postprocedure and 6-months follow-up was demonstrated by optical coherent tomography. This case suggested the utility of DCB as a therapeutic option for covered-stent restenosis.

Time course of restenosis with "black hole" on intravascular ultrasound after implantation of platinum-chromium everolimus-eluting stent: Assessment using optical frequency-domain imaging

Management of in-stent restenosis (ISR) remains challenging even in the drug-eluting stent era. We report the case of a Japanese female with repeated ISR after primary percutaneous coronary intervention (PCI) for acute coronary syndrome. We observed ISR tissue with "black hole" on intravascular ultrasound, which appeared to be heterogeneous tissue on optical frequency-domain imaging (OFDI). Paclitaxel-coated balloon dilatation of the ISR lesion with "black hole" was ineffective. The morphological assessment of ISR tissue using OFDI might be important to treat ISR lesions by PCI. OFDI is a novel tool to observe the difference in the in-stent tissue characteristics. <Learning objective: In-stent restenosis (ISR) remains a clinical problem even in the drug-eluting stent (DES) era. The morphological assessment of ISR tissue using optical frequency-domain imaging (i.e. homogeneous, heterogeneous, and layered types) might be important to treat ISR lesions by percutaneous coronary intervention since the reaction to DES and drug-coating balloon seems to be different according to the in-stent tissue characteristics.>.

Quantified frequency-domain optical coherence tomography analysis for the thin-high signals on restenotic tissue after paclitaxel-coated balloon angioplasty

Thin-high signals (THS), detectable by optical coherence tomography (OCT), represent the paclitaxel coverage of in-stent restenotic tissue. This study was conducted to assess the relationship between THS and angiographic outcomes by means of quantified post-procedural frequency-domain OCT (FD-OCT) analysis. From January 2014 to July 2016, 41 patients underwent FD-OCT-guided percutaneous coronary intervention using paclitaxel-coated balloon (PCB) to prevent in-stent restenosis. Of these, we retrospectively enrolled 32 patients (38 lesions) who underwent a 6- to 9-month follow-up angiogram. THS were assessed quantitatively, as THS length and lumen perimeter length were measured using semi-automated software; %THS was calculated by the following formula; total THS area/lumen perimeter area × 100. THS were detected in all 38 lesions that had undergone PCB angioplasty. THS and %THS were significantly higher in lesions without binary restenosis (3.34 ± 2.11 vs. 11.48 ± 8.53 mm², p = 0.001 and 1.49 ± 0.73 vs. 4.42 ± 2.71%, p = 0.001, respectively). Values for THS, which indicates the paclitaxel coverage on restenotic tissue, are associated with reducing restenosis after PCB for in-stent restenosis.

Relationship between optical coherence tomography-defined in-stent neoatherosclerosis and out-stent arterial remodeling assessed by serial intravascular ultrasound examinations in late and very late drug-eluting stent failure

BACKGROUND

Little is known regarding the association between chronological out-stent vessel remodeling and in-stent tissue characteristics of drug-eluting stent (DES) failure. We aimed to evaluate the relationship between serial vessel remodeling after DES implantation and neoatherosclerosis (NA) assessed by optical coherence tomography (OCT) in patients with DES failure.

METHODS

Forty-eight patients with late and very late stent failure after DES implantation, who underwent intravascular ultrasound (IVUS) at both the initial percutaneous coronary intervention and the time of stent failure and OCT imaging at the time of stent failure, were retrospectively investigated. NA on OCT was defined as neointimal formation with the presence of lipids or calcification inside the stents. Lesions were divided into two groups: those with NA and those without NA (NA: n=21; non-NA: n=27). From the serial IVUS examinations, external elastic membrane (EEM) volume and out-stent plaque volume were normalized by stent length and their changes were compared between the two groups.

RESULTS

The NA group showed older stent age [median, 5.1 years (IQR, 4.8-8.3) vs 1.4 years (IQR, 0.8-4.5); p<0.01] and more prevalent sirolimus-eluting stents (SES; 81.0% vs. 29.6%; p<0.01). IVUS findings of the NA group showed a greater serial increase in both normalized EEM volume and normalized out-stent plaque volume (OSPVI) [1.05 (0.41-1.90) vs. 0.11 (-0.64 to 0.80) mm²; p<0.01; and 0.88 (0.57-1.98) vs. 0.12 (-0.41 to 0.78) mm²; p<0.01]. On multivariate analysis, percentage change in OSPVI (OR, 1.07; 95% CI, 1.01-1.14; p=0.02) and SES (OR, 9.78; 95% CI, 2.20-43.40; p<0.01) remained independent predictors of NA.

CONCLUSIONS

NA in late and very late DES failure was associated with out-stent positive vessel remodeling. In addition to SES, out-stent progressive positive remodeling may help predict NA in late and very late DES failure.

Predictors of Recurrent In-Stent Restenosis After Paclitaxel-Coated Balloon Angioplasty

BACKGROUND

Although paclitaxel-coated balloon (PCB) angioplasty is an effective procedure for in-stent restenosis (ISR) after coronary stenting, recurrent ISR after PCB angioplasty still occurs. The aim of this study was to evaluate the predictors of recurrent ISR after PCB angioplasty for ISR.Methods and Results:A total of 157 ISR lesions treated with PCB angioplasty from January 2014 to May 2015 were retrospectively examined. Recurrent ISR was judged on 6-month follow-up angiography. Clinical, angiographic and procedural parameters were evaluated as possible predictors of recurrent ISR. Recurrent ISR occurred in 13.9% of lesions after PCB angioplasty. On multivariate analysis the following independent predictors of recurrent ISR were identified: (1) smaller acute gain after initial ballooning (OR, 3.06; 95% CI: 1.08-8.71; P=0.04); (2) geographic mismatch between PCB position and initial ballooning (OR, 5.59; 95% CI: 1.64-19.1; P=0.006); and (3) use of percutaneous transluminal coronary rotational atherectomy (PTCRA) at primary percutaneous coronary intervention (PCI; OR, 5.53; 95% CI: 1.89-16.2; P=0.002).

CONCLUSIONS

Optimal expansion at initial ballooning before PCB angioplasty and careful positioning of PCB are important technical tips to prevent recurrent ISR after PCB angioplasty. Recurrent ISR occurred more frequently in severely calcified lesions that required PTCRA at primary PCI.

Current clinical applications of coronary optical coherence tomography

Optical coherence tomography (OCT) is an intra-coronary diagnostic technique that provides detailed imagings of blood vessels in the current cardiac catheterization laboratory. The higher resolution of OCT often provides superior delineation of each structure compared with intravascular ultrasound (IVUS), and it can reliably visualize the microstructure of normal and diseased arteries. The capabilities of OCT are well suited for the identification of calcified plaque and neointima formation after stent implantation. It has been reported that OCT-guided percutaneous coronary intervention (PCI) resulted in equivalent clinical and angiographic outcomes in comparison with IVUS-guided PCI. Recently, the three-dimensional reconstruction of OCT and a real-time point-to-point correspondence between coronary angiographic and OCT/OFDI images have been developed and provide useful information to PCI operators. The unique capabilities of OCT as an investigational tool for high-risk lesions will serve the cardiology community well, as it moves us toward a better understanding of atherosclerotic plaque. In addition, because of the development of new OCT technology, OCT has become a notable catheter-based imaging technology that can provide practical guidance for PCI in clinical settings.

Effect of diabetes mellitus on long-term outcomes after repeat drug-eluting stent implantation for in-stent restenosis

Background

Whether diabetes mellitus (DM) is a predictor of long-term adverse clinical outcomes after repeat drug eluting stent (DES) implantation for DES in-stent restenosis (ISR) remains controversial. We sought to evaluate the effect of DM on the long-term clinical outcomes in patients undergoing repeat DES implantation for DES-ISR lesions.

Methods

In the present study, 254 patients with DES-ISR were divided into DM or non-DM groups according to the presence or absence of DM. All patients received repeat 2^nd generation DES implantation for DES-ISR. The occurrences of major adverse cardiac events (MACEs) over a 2-year follow-up period were compared between the two groups. MACEs were defined as cardiac death, myocardial infarction (MI), and target lesion revascularization (TLR). MACE free survival was investigated with Kaplan-Meier curve analysis. Cox regression analysis was used to identify factors associated with MACEs.

Results

Baseline clinical characteristics were similar between groups, except for the prevalence of early restenosis (lower) in the DM group. Differences in angiographic and procedural characteristics were not significant between groups. The rates of 2-year MACE (30.9 vs. 26.0%; P = 0.453) and TLR (24.7 vs. 19.7%; P = 0.411) were similar between groups. MACE-free survival and TLR-free survival were also similar between groups (P = 0.441 and P = 0.807). Subgroup analysis suggested a significant difference in the MACE (39.0 vs.15.3%, P < 0.001) and TLR occurrence (30.5 vs.8.2%, P < 0.001) and TLR-free survival (lower in early subgroup, P < 0.001) between early and late occurrence of ISR in the non-DM group of patients but not in the DM group. After adjustment for all significant clinical variables, Cox regression analysis indicated that DM was not associated with MACEs (hazard ratio [HR] 1.531, 95% confidence interval [CI] 0.882-2.658, P =0.130). Non-focal type ISR and early ISR were predictors of MACEs (HR 2.671, 95% CI 1.468-4.858,P = 0.001; HR 4.703, 95% CI 2.725-8.117, P < 0.001, respectively).

Conclusions

Patients with DM have similar 2-year clinical outcomes to patients without DM when repeat 2^nd generation DES was used for treatment of DES-ISR. DM is not the predictor of long-term prognosis in patients undergoing repeat 2^nd generation DES for DES-ISR.

Effects of Methotrexate in a Rabbit Model of In-Stent Neoatherosclerosis: An Optical Coherence Tomography Study

This study used optical coherence tomography (OCT) to investigate the effects of systemic methotrexate, in combination with a drug-eluting stent, on in-stent neoatherosclerosis in a rabbit model. Sirolimus-eluting stents were surgically implanted in the right common carotid arteries of 200 male New Zealand White rabbits; the animals received a high-fat diet, beginning one week before stent implantation. Each animal was randomly assigned to 1 of 4 groups, receiving intravenous injections of either methotrexate (0.4 mg/kg) or placebo weekly for 4 or 12 weeks. Stented arterial segments were harvested after stenting for 4 or 12 weeks, and processed for OCT and histological analysis. Prior to harvesting the arterial segments, blood was collected for the determinations of cytokine levels. Compared with the control animals, the methotrexate-treated animals showed lower rates of lipid-rich intima and per-strut low-signal intensity layers, smaller neointimal areas, and reduced neointimal thickness; larger fibrous cap thicknesses and smaller lumen areas were also seen in the animals receiving methotrexate. The levels of serum interleukin, adhesion molecules, and nuclear factor-κB p65 decreased and IL-10 level increased in the methotrexate-treated animals. Targeting the pro-inflammatory pathways may be an effective way to prevent restenosis without the long-term risk of late thrombosis.