Vascular responses to coronary calcification following implantation of newer-generation drug-eluting stents in humans: impact on healing

Pathological Evaluation of Predictors for Delayed Endothelial Coverage After Currently Available Drug-eluting Stent Implantation in Coronary Arteries: Impact of Lesions With Acute and Chronic Coronary Syndromes

BACKGROUND

The optimal duration of dual antiplatelet therapy after currently available drug-eluting stent (DES) implantation to prevent stent thrombosis (ST) remains controversial. Delayed healing is frequently identified as a leading cause of ST in the early phase. However, a thorough pathological investigation into strut coverage after currently available DES implantation is lacking-a gap addressed in the current study.

METHODS

From our autopsy registry of 199 stented lesions, 4,713 struts from 66 currently available DES-stented lesions with an implant duration ≤370 days were histologically evaluated. Endothelial coverage was defined as the presence of luminal endothelial cells overlying struts and an underlying smooth muscle cell layer. The stented lesions were classified into acute coronary syndrome (ACS) (n = 40) and chronic coronary syndrome (CCS) (n = 26) groups and were compared. Endothelial coverage predictors were identified through logistic analysis.

RESULTS

Although ACS and CCS lesions presented comparable clinical characteristics, including age, sex, and cause of death, the latter exhibited a significantly higher prevalence of chronic kidney disease and hemodialysis than the former (33.3% vs. 65.2%; p = 0.02, 7.7% vs. 30.4%; p = 0.02). The poststent implant median duration was significantly shorter in ACS lesions than in CCS lesions (13 [IQR 5-26 days] vs. 40 [IQR 16-233 days]; p < 0.01). The endothelial coverage percentage was 3.5% at 30 days and 27.7% at 90 days after currently available DES implantation. Multivariable logistic regression analysis implicated implant duration of ≤90 days [odds ratio (OR), 0.009; 95% confidence interval (CI), 0.006-0.012; p < 0.01], superficial calcification (OR, 0.11; 95% CI, 0.07-0.17; p < 0.01), ACS culprit site (OR, 0.29; 95% CI, 0.09-0.94; p = 0.039), and circumferentially durable polymer-coated DES (OR, 0.32; 95% CI, 0.24-0.41; p < 0.01) as delayed endothelial coverage predictors.

CONCLUSIONS

Endothelial coverage was limited at 90 days after currently available DES implantation, and the ACS culprit site and circumferentially durable polymer-coated DES were identified as independent predictors of delayed endothelial coverage. Our findings suggest the importance of underlying plaque morphology and stent technology for vessel healing after such implantation.

Incidence of Acute Thrombotic Occlusion and Its Predictors After Contemporary Femoropopliteal Endovascular Therapy in Patients With Peripheral Artery Disease

PURPOSE

This study investigated the incidence of acute thrombotic occlusion (ATO) and its predictors after contemporary femoropopliteal (FP) endovascular therapy (EVT) for peripheral artery disease.

MATERIALS AND METHODS

We retrospectively examined 763 limbs (chronic limb-threatening ischemia [CLTI]: 44%, involving popliteal lesion: 44%) in 644 patients (mean age: 75±9 years, male: 71%, hemodialysis: 34%) who successfully underwent EVT with contemporary FP devices (drug-coated stent: n=220, stent graft: n=158, drug-eluting stent: n=150, drug-coated balloon [DCB]: n=235) from June 2012 to July 2020. The outcome measure was ATO defined as acute onset of claudication and/or signs of CLTI in combination with angiographic evidence of occlusive thrombus formation within the treated segment. Cox proportional hazards regression models were used to identify baseline characteristics associated with the incidence of ATO after EVT treated with scaffold. To determine the impact of ATO occurrence and creatine phosphokinase (CPK) elevation on the subsequent composite outcome of mortality or major amputation, we developed the Cox model in which the trichotomous variable (free from ATO, ATO without CPK elevation, and ATO with CPK elevation) was a time-dependent covariate.

RESULTS

The 24-month incidence of ATO in the overall population was 4.3%±0.8% (DCB: 1.0%±0.7% vs scaffold: 5.8%±1.1%, p<0.01). Hemodialysis (hazard ratio [HR]: 2.63, p=0.02) and involving popliteal lesion (HR: 8.22, p<0.01) were independently associated with an increased risk of ATO in patients treated with scaffold. Both ATO without CPK elevation and ATO with CPK elevation were significantly associated with a composite outcome of mortality or major amputation comparing free from ATO, with an HR of 2.39 and 9.87, respectively (p=0.02 and p<0.01).

CONCLUSION

We found a substantial incidence of ATO after contemporary FP-EVT, particularly with scaffold. Hemodialysis and involving popliteal lesion were significantly associated with ATO risk in patients treated with scaffold. The occurrence of ATO, particularly with CPK elevation, was associated with an increased risk of a subsequent composite outcome of mortality or major amputation. The scaffold was safely used in patients without those risk factors of ATO, but a non-scaffolding strategy should be considered for patients with more risk factors.

CLINICAL IMPACT

The scaffold was safely used in patients without hemodialysis and involving popliteal lesion, but a non-scaffolding strategy should be considered for patients with those risk factors. The occurrence of ATO, particulary with CPK elevation, was of high risk of mortality or amputation.

Unusual optical coherence tomography findings resembling sea anemone tentacles after orbital atherectomy for nodular calcification lesions in a haemodialysis patient: a case report

Background

Optical coherence tomography (OCT) can be used to characterize the details of calcified plaques because it allows high-resolution evaluation of coronary plaques, thrombi, and calcium.

Case summary

A 72-year-old man on haemodialysis who had stenosis with a severe calcified lesion at the left anterior descending artery underwent percutaneous coronary intervention. Pre-intervention OCT imaging identified a nodular calcification (NC) that protruded into the lumen of the left anterior descending artery. To treat this lesion, we performed orbital atherectomy using the Diamondback 360 coronary orbital atherectomy system. After ablation of the nodular lesions at low and high speed, OCT showed newly emerged granular and filamentous structures that resembled sea anemone tentacles (these represented calcified nodule-like OCT findings). These structures appeared to extend from the proximal part of the ablated small NC, and shifted distally after balloon dilatation. Stent implantation was performed to entirely cover these structures, with no resulting complications. However, early in-stent restenosis occurred at 4 months follow-up.

Discussion

A tentacle-like OCT appearance in calcified lesions has not been previously reported. This represents a very rare and interesting imaging finding that reflects the relationship and origins of NCs and calcified nodules. The maturity of the NC lesions and the lateral sanding style of the orbital atherectomy system may have contributed to this striking OCT finding.

Tissue responses to everolimus-eluting stents implanted in severely calcified lesions following atherectomy

Histopathological examination has revealed that stents on severely calcified plaques were associated with delayed vascular healing. Although atherectomy devices can increase the number of malapposed struts, tissue responses to implanted drug eluting stents in atherectomy patients remain largely unknown. This retrospective observational study included 30 patients who underwent atherectomy and everolimus-eluting stent (EES) deployment for severely calcified coronary lesions (biodegradable polymer EES (BP-EES), n = 15; durable polymer EES (DP-EES), n  = 15). Optical coherence tomography was carried out at baseline and follow-up, and struts with acute stent malapposition (ASM) were categorized as struts on modified calcium (mod-Ca), non-modified calcium (non-mod-Ca), or non-calcium (non-Ca). Adequate vascular healing, defined as ASM resolution with neointimal coverage, was compared between the BP-EES and DP-EES groups. Multivariate linear regression analysis using a generalized estimated equation revealed that BP-EES use was associated with significantly better adequate vascular healing compared with DP-EES (odds ratio [OR]: 3.691, 95% confidence interval [CI] 1.175-11.592, P = 0.025). adequate vascular healing was associated with the underlying plaque morphology (mod-Ca vs non-mod-Ca: OR 2.833, 95% CI 1.491-5.384, P = 0.001; non-Ca vs non-mod-Ca: OR 1.248, 95% CI 0.440-3.543, P = 0.677). This study demonstrates that drug-eluting stent selection and calcium modification are possible factors affecting vascular healing of malapposed struts in severely calcified lesions.

Management strategies for heavily calcified coronary stenoses: an EAPCI clinical consensus statement in collaboration with the EURO4C-PCR group

Since the publication of the 2015 EAPCI consensus on rotational atherectomy, the number of percutaneous coronary interventions (PCI) performed in patients with severely calcified coronary artery disease has grown substantially. This has been prompted on one side by the clinical demand for the continuous increase in life expectancy, the sustained expansion of the primary PCI networks worldwide, and the routine performance of revascularization procedures in elderly patients; on the other side, the availability of new and dedicated technologies such as orbital atherectomy and intravascular lithotripsy, as well as the optimization of the rotational atherectomy system, has increased operators' confidence in attempting more challenging PCI. This current EAPCI clinical consensus statement prepared in collaboration with the EURO4C-PCR group describes the comprehensive management of patients with heavily calcified coronary stenoses, starting with how to use non-invasive and invasive imaging to assess calcium burden and inform procedural planning. Objective and practical guidance is provided on the selection of the optimal interventional tool and technique based on the specific calcium morphology and anatomic location. Finally, the specific clinical implications of treating these patients are considered, including the prevention and management of complications and the importance of adequate training and education.

Pathological Analysis of Medial and Intimal Calcification in Lower Extremity Artery Disease: Impact of Hemodialysis

Background

The prevalence and degree of lower extremity artery disease in hemodialysis (HD) patients is higher than in the general population. However, the pathological features have not yet been evaluated.

Objectives

The aim of the study was: 1) to compare lesion characteristics of lower extremity artery disease in HD vs non-HD patients; and 2) to determine factors associated with severe medial calcification.

Methods

Seventy-seven lower limb arteries were assessed from 36 patients (median age 77 years; 23 men; 21 HD and 15 non-HD) who underwent autopsy or lower limb amputation. Arteries were serially cut at 3- to 4-mm intervals creating 2,319 histological sections. Morphometric analysis and calcification measurements were performed using ZEN software. Calcification with a circumferential angle (arc) ≥180° was defined as severe calcification. Multivariable logistic regression was used to identify risk factors for severe medial calcification.

Results

The degree of the medial calcification arc was significantly higher in the HD group compared to the non-HD group (P < 0.0001). In the multivariable analysis, HD was associated with severe medial calcification in below-the-knee lesions (OR: 17.1; P = 0.02). The degree of intimal calcification in above-the-knee lesions was also significantly higher in HD patients with a higher prevalence of advanced atherosclerotic plaque (P = 0.02). The prevalence of severe bone formation was more common in the HD patients (P = 0.01).

Conclusions

Hemodialysis patients demonstrated a higher degree of medial and intimal calcification compared with non-HD patients. The difference was more prominent in the medial calcification of below-the-knee lesions.

Poor Below Knee Runoff Impacts Femoropopliteal Stent Failure and Fluoropolymer Antithrombotic Effect in Healthy Swine Model

OBJECTIVE

Poor below knee (BTK) runoff is a predictor of stent failure after endovascular femoropopliteal artery treatment; however, lack of pathological evaluation has prevented characterisation of stent failure. The study aimed to investigate the impact of poor BTK runoff and the antithrombotic effect of the polymer of fluoropolymer coated paclitaxel eluting stents (FP-PESs) in a healthy swine femoropopliteal artery model.

METHODS

FP-PESs and bare metal stents (BMSs) and FP-PES and polymer free paclitaxel coated stents (PF-PCSs) were implanted in the bilateral femoral arteries of healthy swine (n = 6, respectively) following coil embolisation in both tibial arteries to induce poor BTK runoff. Histological assessment and intravascular imaging device evaluation were performed at one month. The Japanese Association for Laboratory Animal Science approved the study protocol (reference number: IVT22-90).

RESULTS

Optical coherence tomography showed significantly lower percent area stenosis in FP-PES compared with BMS (37.3%, [interquartile range (IQR), 25.6 - 54.3] % vs. 92.5% [IQR, 75.5 - 96.1] %, respectively, p = .031), and PF-PCS (8.3% [IQR, 4.5 - 27.0] % vs. 31.2% [IQR, 23.3 - 52.2] %, respectively, p = .031). Histopathological evaluation demonstrated that thin fibrin attachment without re-stenosis was the most dominant neointimal tissue characteristic in FP-PES. On the other hand, neointimal tissue characteristics with significant restenosis of BMS and PF-PCS were mainly organising or organised thrombus.

CONCLUSION

Organising and or organised thrombus attachment due to poor BTK runoff was the main cause of in stent restenosis of the swine femoral artery. FP-PES demonstrated the least percent area stenosis, suggesting the importance of the antithrombotic effect of polymer.

Mass Spectrometry Imaging of Biomaterials

The science related to biomaterials and tissue engineering accounts for a growing part of our knowledge. Surface modifications of biomaterials, their performance in vitro, and the interaction between them and surrounding tissues are gaining more and more attention. It is because we are interested in finding sophisticated materials that help us to treat or mitigate different disorders. Therefore, efficient methods for surface analysis are needed. Several methods are routinely applied to characterize the physical and chemical properties of the biomaterial surface. Mass Spectrometry Imaging (MSI) techniques are able to measure the information about molecular composition simultaneously from biomaterial and adjacent tissue. That is why it can answer the questions connected with biomaterial characteristics and their biological influence. Moreover, this kind of analysis does not demand any antibodies or dyes that may influence the studied items. It means that we can correlate surface chemistry with a biological response without any modification that could distort the image. In our review, we presented examples of biomaterials analyzed by MSI techniques to indicate the utility of SIMS, MALDI, and DESI-three major ones in the field of biomaterials applications. Examples include biomaterials used to treat vascular system diseases, bone implants with the effects of implanted material on adjacent tissues, nanofibers and membranes monitored by mass spectrometry-related techniques, analyses of drug-eluting long-acting parenteral (LAPs) implants and microspheres where MSI serves as a quality control system.

Angiographic Coronary Calcification: A Simple Predictor of Long-Term Clinical Outcomes in Patients with Acute Myocardial Infarction

AIMS

Coronary calcification detected by coronary angiography is a simple risk marker for long-term clinical outcomes in stable coronary artery disease. However, the significance of angiographic coronary calcification in the culprit lesion of acute myocardial infarction (AMI) has not been fully discussed. The purpose of this retrospective study was to assess the usefulness of angiographic coronary calcification as a risk marker for long-term clinical outcomes following percutaneous coronary intervention to the culprit lesions of AMI.

METHODS

We included 1209 patients with AMI and divided them into the none-mild calcification group (n=923) and the moderate-severe calcification group (n=286) according to angiographic coronary calcification in the culprit lesion of AMI. The primary endpoint was the occurrence of major adverse cardiac events (MACE), which was defined as a composite of all-cause death, nonfatal MI, readmission for heart failure, and ischemia-driven target vessel revascularization.

RESULTS

The median follow-up duration was 542 (Q1: 182, Q3: 990) days. A total of 345 MACE were observed during the study period. The occurrence of MACE was significantly greater in the moderate-severe calcification group than in the none-mild calcification group (43.4% vs. 23.9%, p＜0.001). In the multivariate Cox hazard model, moderate-severe calcification was significantly associated with MACE (hazard ratio 1.302, 95% confidence interval 1.011-1.677, p=0.041) after controlling multiple confounding factors.

CONCLUSIONS

Angiographically moderate to severe calcification in AMI culprit lesion was associated with long-term worse clinical outcomes. Angiographic coronary calcification can be a simple risk marker in patients after AMI.

Comparison of long-term outcome in patients with calcified stenosis treated with intravascular lithotripsy or with modified balloon angioplasty: a propensity score-adjusted study

Background

The aim of this two-center, all-comers registry was to compare the effectiveness and safety of intravascular lithotripsy (IVL) to that of modified balloon angioplasty (MB). MB angioplasty using a cutting or scoring balloon is commonly used in patients with calcified coronary arteries. IVL is a new technology for lesion preparation. This is the first study to compare MB with IVL.

Methods

The cohort included all patients treated by MB angioplasty or IVL between 2019 and 2021. The primary endpoint was strategy success (<20% residual stenosis). The secondary endpoint was long-term safety outcomes [cardiac death, acute myocardial infarction (AMI), target lesion failure/revascularization (TVR)]. Quantitative coronary angiography (QCA) was performed in all patients. Primary and secondary endpoints were compared using inverse probability of treatment weighting (IPTW) for treatment effect estimation.

Results

A total of n = 86 patients were treated by IVL and n = 92 patients by MB angioplasty. The primary endpoint was reached in 152 patients (85.4%). Patients in the IVL group had less residual stenosis (5.8% vs. 22.8%; p = 0.001) in QCA. Weighted multivariable regression analysis revealed that IVL had a significant positive effect on reaching the primary endpoint of strategy success [odds ratio (OR) 24.58; 95% confidence interval (95% CI) 7.40-101.86; p = 0.001]. In addition, severe calcification was shown to result in a lower probability of achieving the primary endpoint (OR 0.08; 95% CI 0.02-0.24; p = 0.001). During the follow-up period (450 days) there was no difference in cardiovascular mortality rate [IVL (n = 5) 2.8% vs. MB (n = 3) 1.7%; p = 0.129]. Patients with unstable angina at the time of the index procedure had the highest probability of cardiovascular death [hazard ratio (HR) 7.136; 95% CI 1.248-40.802; p = 0.027]. No differences were found in long-term rates of AMI (IVL 1.7% vs. MB 2.8%; p = 0.399; IVL HR 2.73; 95% CI 0.4-17.0; p = 0.281) or TVR (IVL 5.6% vs. MB 9%; p = 0.186; IVL HR 0.78; 95% CI 0.277-2.166; p = 0.626).

Conclusion

IVL leads to a significantly better angiographic intervention outcome compared to MB angioplasty in our cohort. During long-term follow-up, no differences in cardiovascular mortality, rate of acute myocardial infarction, or target lesion failure/revascularization were observed.

Optical coherence tomography factors for adverse events in patients with severe coronary calcification

BACKGROUND

Severe coronary calcification is a factor for worse outcomes after percutaneous coronary intervention.

AIMS

To identify factors of pre- and post-stent optical coherence tomography (OCT) for device-oriented clinical endpoints (DoCE) in patients with severely calcified lesions requiring drug-eluting stent (DES) implantation.

METHODS

A total of 237 consecutive patients with stable coronary disease who underwent OCT imaging of severe coronary lesions were included. Lesions with a maximum calcium angle >180°, maximum calcium thickness > 0.5 mm, and calcium length > 5 mm were defined as having severe calcification.

RESULTS

The prevalence of eruptive calcified nodules (41% vs. 18%, p = 0.002) and medial dissection with calcified flaps (59% vs. 26%, p < 0.001) was significantly higher in patients with DoCE (n = 34) than those without DoCE (n = 203). Multivariate analyses demonstrated that the presence of a medial dissection with calcified flap within the DES-implanted segment was independently associated with a higher incidence of DoCE (odds ratio, 3.367; 95% confidence interval, 1.503-7.543; p = 0.003). The combined presence of eruptive calcified nodules and medial dissection with calcified flaps was associated with a higher incidence of DoCE (p < 0.001) during a median of 756 days after DES implantation.

CONCLUSIONS

OCT-defined severely calcified lesions with eruptive calcified nodules and medial dissection with calcified flaps were associated with a higher incidence of DoCE after DES implantation.

Angioscopic Evaluation of Vascular Response After Fluoropolymer-Based Drug-Eluting Stent Implantation for Femoropopliteal Artery Lesions

BACKGROUND

Although favorable clinical outcomes have been demonstrated for fluoropolymer-based paclitaxel-eluting stents (FP-DES) in the treatment of femoropopliteal lesions, the vascular response after implantation has not been systematically studied through intravascular imaging.Methods and Results: We angioscopically compared FP-DES: 24 in the early phase (mean [±SD] 3±1 months), 26 in the middle phase (12±3 months), and 20 in the late phase (≥18 months) after implantation. The dominant neointimal coverage grade, heterogeneity of neointimal coverage grade, and thrombus adhesion in the stent segment were evaluated. Neointimal coverage was graded as follows: Grade 0, stent struts exposed; Grade 1, struts bulging into the lumen, although covered; Grade 2, struts embedded in the neointima, but visible; Grade 3, struts fully embedded and invisible. Dominant neointimal coverage and heterogeneity grades were significantly higher in the middle and late phases than in the early phase (all P<0.05), but did not differ significantly between the middle and late phases. The incidence of thrombus adhesion was recorded for all stents in each of the 3 different phases.

CONCLUSIONS

The middle and late phases after FP-DES implantation were associated with significantly higher dominant neointimal coverage and heterogeneity grades than the early phase. However, thrombus adhesion was observed in all phases after FP-DES implantation. Arterial healing may not be completed even in the late phase after FP-DES implantation.

[Invasive and non-invasive imaging analysis for calcified coronary artery lesions]

Coronary calcifications are frequently identified within coronary lesions as their incidence increases with age and cardiovascular risk factors. Their location can be superficial or deep, according to different pathological process. In all cases, the presence of calcifications within the vascular wall predicts poor clinical prognosis and unfavorable evolution after percutaneous revascularization. Coronary calcifications can be analyzed by angiography, CT or intracoronary imaging (IVUS or OCT) with variable accuracies. Angiography is the most frequently used method but is not very sensitive (sensitivity close to 50%) and insufficient for their precise quantification. The CT scan is a more effective non-invasive method leading to an accurate analysis of the lesion before coronary angiography. IVUS and OCT have an excellent spatial resolution and are the most sensitive methods for the identification (present in nearly 75-80% of lesions) and quantification of calcifications. These intracoronary imaging techniques offer interesting perspectives for identification of the highest-risk lesions, PCI procedures planning (including the choice of an optimal dedicated plaque preparation devices), the monitoring of their execution and the evaluation of the immediate post-stenting results.

Clinical Outcomes and Unique Restenosis of Calcified Nodule in Heavily Calcified Coronary Artery

AIMS

Calcified nodule (CN) has been known as the advanced stage of coronary calcification. However, clinical outcomes following percutaneous coronary intervention (PCI) to CN remain unknown. This study aimed to compare clinical outcomes, including target lesion revascularization (TLR), between calcified coronary lesions with and without CN.

METHODS

Two hundred forty-nine lesions undergoing intravascular ultrasound-guided PCI with rotational atherectomy (RA) were enrolled and divided into the CN group (n=100) and the non-CN group (n=149) according to the presence of CN. The cumulative incidence of clinically driven TLR (CD-TLR) and the reasons for CD-TLR were compared between the CN and non-CN groups.

RESULTS

The incidence of CD-TLR was significantly higher in the CN group than in the non-CN group. In the landmark analysis at 1 year, the CN group showed a significantly higher incidence of CD-TLR within 1 year. However, the incidence of CD-TLR beyond 1 year was numerically lower in the CN group than in the non-CN group. In the multivariate Cox hazard model, CN was significantly associated with CD-TLR. In the CN group, in-stent CN was the major reason for CD-TLR (52%) and was observed mainly within 1 year (90%).

CONCLUSIONS

In the heavily calcified lesions requiring RA, CN was the factor associated with the higher rate of CD-TLR especially within 1 year. The timing of CD-TLR in lesions with CN may indicate that the process of CN protruding through the struts was progressed monthly.

Vascular Response After Everolimus-Eluting Stent in Acute Myocardial Infarction Caused by Calcified Nodule

BACKGROUND

Patients with acute myocardial infarction (AMI) caused by calcified nodules (CN) have worse clinical outcomes following primary percutaneous coronary intervention (PCI). This study investigated the late vascular response after everolimus-eluting stent (EES) implantation assessed by optical coherence tomography (OCT) in patients with AMI caused by CN, by comparing with plaque rupture (PR) and plaque erosion (PE).Methods and Results: Based on the OCT findings in AMI culprit lesions before PCI, a total of 141 patients were categorized into 3 groups (PR, PE, or CN), and the OCT findings immediately and 10 months after PCI were compared. The frequency of PR, PE, and CN was 85 (60%), 45 (32%), and 11 patients (8%), respectively. In the 10-month follow-up OCT, the frequency of lesions with uncovered struts and lesions with malapposed struts were highest in the CN group, followed by the PR and PE groups (82% vs. 52% vs. 40%, P=0.042 and 73% vs. 26% vs. 16%, P<0.001, respectively). The incidence of intra-stent thrombus, re-appearance of CN within the stent, and target lesion revascularization were higher in the CN group compared with the PR and PE groups (36% vs. 9% vs. 7%, P=0.028; 27% vs. 0% vs. 0%, P<0.001; and 18% vs. 2% vs. 2%, P=0.024, respectively).

CONCLUSIONS

Late arterial healing response at 10 months after EES implantation in the CN was worse compared with PR and PE in patients with AMI.

An Implantable Artificial Atherosclerotic Plaque as a Novel Approach for Drug Transport Studies on Drug-Eluting Stents

Atherosclerotic arteries are commonly treated using drug-eluting stents (DES). However, it remains unclear whether and how the properties of atherosclerotic plaque affect drug transport in the arterial wall. A limitation of the currently used atherosclerotic animal models to study arterial drug distribution is the unpredictability of plaque size, composition, and location. In the present study, the aim is to create an artificial atherosclerotic plaque-of reproducible and controllable complexity and implantable at specific locations-to enable systematic studies on transport phenomena of drugs in stented atherosclerosis-mimicking arteries. For this purpose, mixtures of relevant lipids at concentrations mimicking atherosclerotic plaque are incorporated in gelatin/alginate hydrogels. Lipid-free (control) and lipid-rich hydrogels (artificial plaque) are created, mounted on DES and successfully implanted in porcine coronary arteries ex-vivo. Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) is used to measure local drug distribution in the arterial wall behind the prepared hydrogels, showing that the lipid-rich hydrogel significantly hampers drug transport as compared to the lipid-free hydrogel. This observation confirms the importance of studying drug transport phenomena in the presence of lipids and of having an experimental model in which lipids and other plaque constituents can be precisely controlled and systematically studied.

Plasma Proteome Profiling of Patients With In-stent Restenosis by Tandem Mass Tag-Based Quantitative Proteomics Approach

Background

Despite the widespread application of new drug-eluting stents, a considerable portion of patients experience in-stent restenosis (ISR). To date, the pathophysiologic mechanisms of ISR remain poorly understood.

Methods

In this study, we collected plasma samples from ISR patients (n = 29) and non-ISR patients (n = 36) after drug-eluting stent implantation, as well as from healthy controls (HCs) (n = 32). Our goal was to investigate differences in plasma protein profiles using tandem mass tag (TMT) labeling coupled with liquid chromatography and tandem mass spectrometry. The proteomic data were validated by enzyme-linked immunosorbent assay (ELISA). Bioinformatic analyses were conducted to analyze potential pathways and protein-protein interaction (PPI) involved in ISR.

Results

A total of 1,696 proteins were identified, of which 278 differed in protein abundance between non-ISR and HCs, 497 between ISR and HCs, and 387 between ISR and non-ISR, respectively. Bioinformatic analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and PPI, further demonstrated that differentially abundant proteins between ISR and non-ISR are involved in several crucial biological processes and signaling pathways, such as focal adhesion, platelet activation, Rap1 signaling, regulation of actin cytoskeleton, and cholesterol metabolism. Among the identified differentially abundant proteins in ISR, 170 were increased in abundance relative to both non-ISR patients and HCs. Some of these proteins were identified to have critical functions for atherosclerosis development and might be involved in ISR pathology. Among these proteins, 3 proteins with increased abundance including fetuin-B, apolipoprotein C-III (APOC3), and cholesteryl ester transfer protein (CETP) were confirmed by ELISA.

Conclusions

This is the first study provided a comprehensive proteomic profile to understand ISR pathology, which may help identify early diagnostic biomarkers and therapeutic targets.

Drug-eluting stents for the treatment of coronary artery disease: A review of recent advances

INTRODUCTION

Percutaneous coronary intervention is a widely used procedure for the treatment of coronary artery disease to relieve narrowing or occlusion and improve blood supply. Although only balloon angioplasty was performed in the early period, coronary stents were developed later and coronary drug-eluting stents were introduced to decrease in-stent restenosis, which is related to the proliferation and migration of vascular smooth muscle cells.

AREAS COVERED

The drug-eluting stents are composed of a metallic or polymeric platform, specific drug, and polymers or coating for drug release. In this article, the recent advances in drug-eluting stent technologies for the treatment of coronary artery disease and adjunctive antiplatelet therapy after drug-eluting stent implantation will be reviewed.

EXPERT OPINION

The need for further advances in drug-eluting stents or fully bioresorbable coronary scaffolds still exists to improve patient survival or clinical outcomes. The use for different actions or of combinations of drugs with several actions can be potential. Technological refinement and progress in manufacturing to improve mechanical integrity are needed, particularly for fully bioresorbable scaffolds. For antiplatelet therapy after stenting, clinical bleeding reduction strategies, such as a shortened duration of dual-antiplatelet therapy, are in progress.

10-Year All-Cause Mortality Following Percutaneous or Surgical Revascularization in Patients With Heavy Calcification

OBJECTIVES

The aim of this study was to assess 10-year all-cause mortality in patients with heavily calcified lesions (HCLs) undergoing percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG).

BACKGROUND

Limited data are available on very long term outcomes in patients with HCLs according to the mode of revascularization.

METHODS

This substudy of the SYNTAXES (Synergy Between PCI With Taxus and Cardiac Surgery Extended Survival) study assessed 10-year all-cause mortality according to the presence of HCLs within lesions with >50% diameter stenosis and identified during the calculation of the anatomical SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) score among 1,800 patients with the 3-vessel disease and/or left main disease randomized to PCI or CABG in the SYNTAX trial. Patients with HCLs were further stratified according to disease type (3-vessel disease or left main disease) and assigned treatment (PCI or CABG).

RESULTS

The 532 patients with ≥1 HCL had a higher crude mortality rate at 10 years than those without (36.4% vs 22.3%; HR: 1.79; 95% CI: 1.49-2.16; P < 0.001). After adjustment, an HCL remained an independent predictor of 10-year mortality (HR: 1.36; 95% CI: 1.09-1.69; P = 0.006). There was a significant interaction in mortality between treatment effect (PCI and CABG) and the presence or absence of HCLs (P_interaction = 0.005). In patients without HCLs, mortality was significantly higher after PCI than after CABG (26.0% vs 18.8%; HR: 1.44; 95% CI: 0.97-1.41; P = 0.003), whereas in those with HCLs, there was no significant difference (34.0% vs 39.0%; HR: 0.85; 95% CI: 0.64-1.13; P = 0.264).

CONCLUSIONS

At 10 years, the presence of an HCL was an independent predictor of mortality, with a similar prognosis following PCI or CABG. Whether HCLs require special consideration when deciding the mode of revascularization beyond their current contribution to the anatomical SYNTAX score deserves further evaluation. (Synergy Between PCI With TAXUS and Cardiac Surgery: SYNTAX Extended Survival [SYNTAXES], NCT03417050; SYNTAX Study: TAXUS Drug-Eluting Stent Versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries [SYNTAX], NCT00114972).

Arsenic trioxide activates yes-associated protein by lysophosphatidic acid metabolism to selectively induce apoptosis of vascular smooth muscle cells

Inhibition of vascular smooth muscle cells (VSMCs) proliferation without dysregulating endothelial cells (ECs) may provide an ideal therapy for in-stent restenosis. Due to its anti-proliferation effect on VSMCs and pro-endothelium effect, arsenic trioxide (ATO) has been used in a drug-eluting stent in a recent clinical trial. However, the underlying mechanism by which ATO achieves this effect has not been determined. In the present work, we showed that ATO induced apoptosis in VSMCs but not in ECs. Mechanistically, ATO achieved this through modulation of cellular metabolism to increase lysophosphatidic acid (LPA) in VSMCs, while LPA concentration was stable in ECs. The elevated LPA facilitated the nuclear accumulation and initiated the transcriptional function of Yes-associated protein (YAP) in VSMCs. YAP regulated the transcription of N6-Methyladenosine (m⁶A) modulators (Mettl14 and Wtap) to increase the m⁶A methylation levels of apoptosis-related genes to induce their high expression and exacerbate VSMCs apoptosis. On the other hand, YAP nuclear accumulation in ECs was not observed. Collectively, our data exhibited the molecular process involved in selective apoptosis of VSMCs induced by ATO.

Overcoming challenges in refining the current generation of coronary stents

INTRODUCTION

Late stent thrombosis caused by delayed vascular healing and prolonged local inflammation were major drawbacks of 1^st generation drug-eluting stents (DES). Strut design, biocompatibility of polymer, and drug-release profiles were improved in 2^nd and 3rdgeneration DES. Accordingly, the indications for percutaneous coronary intervention with DES have been expanded to more complex patients and lesions. Despite these improvements, significant barriers such as greater flexibility in the duration of dual-antiplatelet therapy (DAPT) as well as reducing long-term stent-related events remain. To achieve ideal short- and long-term results, these existing limitations need to be overcome.

AREAS COVERED

We will discuss the current limitations of coronary DES and how they might be overcome from pathological and clinical viewpoints.

EXPERT OPINION

Optimizing DAPT duration after stent implantation and prevention of in-stent neoatherosclerosis are two major issues in current DES. Overcoming these drawbacks is a prerequisite toward achieving better short- and long-term clinical outcomes. New technologies including platform design, polymer types, and anti-proliferative agent itself might lead to further improvements. Although the initial experience with bioresorbable scaffold/stents (BRS) was disappointing, positive results of clinical studies regarding novel BRS are raising expectations. Overall, further device innovation is desired for overcoming the limitations of current DES.

Finite element analysis in clinical patients with atherosclerosis

Endovascular plaque composition is strongly related to stent strut stress and is responsible for strut fatigue, stent failure, and possible in-stent restenosis. To evaluate the effect of plaque on artery wall resistance to expansion we performed in silico analysis of atherosclerotic vessels. We generated finite element models from in vivo intravascular ultrasound virtual histology images to determine local artery surface stiffness and determined which plaque structures have the greatest influence. We validated the predictive capacity of our modeling approach by testing an atherosclerotic peripheral artery ex vivo with pressure-inflation testing at physiological pressures ranging from 10 to 200 mmHg. For this purpose, the in silico deformation of the arterial wall was compared to that observed ex vivo. We found that calcification had a positive effect on surface stiffness with fibrous plaque and necrotic core having negative effects. Additionally, larger plaque structures demonstrated significantly higher average surface stiffness and calcification located nearer the lumen was also shown to increase surface stiffness. Therefore, more developed plaques will have greater resistance to expansion and higher stent strut stress, with calcification located near the lumen further increasing stress in localized areas. Thus, it may be expected that such plaque structures may increase the likelihood of localized stent strut fracture.

A Recombinant Fusion Construct between Human Serum Albumin and NTPDase CD39 Allows Anti-Inflammatory and Anti-Thrombotic Coating of Medical Devices

Medical devices directly exposed to blood are commonly used to treat cardiovascular diseases. However, these devices are associated with inflammatory reactions leading to delayed healing, rejection of foreign material or device-associated thrombus formation. We developed a novel recombinant fusion protein as a new biocompatible coating strategy for medical devices with direct blood contact. We genetically fused human serum albumin (HSA) with ectonucleoside triphosphate diphosphohydrolase-1 (CD39), a promising anti-thrombotic and anti-inflammatory drug candidate. The HSA-CD39 fusion protein is highly functional in degrading ATP and ADP, major pro-inflammatory reagents and platelet agonists. Their enzymatic properties result in the generation of AMP, which is further degraded by CD73 to adenosine, an anti-inflammatory and anti-platelet reagent. HSA-CD39 is functional after lyophilisation, coating and storage of coated materials for up to 8 weeks. HSA-CD39 coating shows promising and stable functionality even after sterilisation and does not hinder endothelialisation of primary human endothelial cells. It shows a high level of haemocompatibility and diminished blood cell adhesion when coated on nitinol stents or polyvinylchloride tubes. In conclusion, we developed a new recombinant fusion protein combining HSA and CD39, and demonstrated that it has potential to reduce thrombotic and inflammatory complications often associated with medical devices directly exposed to blood.

Antiplatelet Effect of Single Antiplatelet Therapy With Prasugrel and Oral Anticoagulation After Stent Implantation in a Rabbit Arteriovenous Shunt Model

Background: Antiplatelet therapy following stent implantation in patients requiring oral anticoagulation (OAC) is controversial because triple therapy (i.e., dual antiplatelet therapy [DAPT] with OAC) is associated with a high risk of bleeding. Methods and Results: In this study, 21 rabbits were divided into 5 groups: prasugrel and warfarin (Prasugrel+OAC group); aspirin and warfarin (Aspirin+OAC group); prasugrel, aspirin, and warfarin group (Triple group); prasugrel and aspirin (Conventional DAPT group); and no medication (Control group). The treated groups were administered medication for 1 week. An arteriovenous shunt loop was established from the rabbit carotid artery to the jugular vein and 2 bare metal stents were deployed in a silicone tube. After 1 h of circulation, the volume of thrombi was evaluated quantitatively by measuring the amount of protein. Bleeding time was measured at the same time. The volume of the thrombus (amount of protein) around stent struts was lowest in the Triple group, followed by the Prasugrel+OAC and Conventional DAPT groups, and was highest in the Control group. Bleeding time was the longest in the Triple group, followed by the Aspirin+OAC, Prasugrel+OAC, Conventional DAPT, and Control groups. Conclusions: This study suggests that prasugrel with OAC may be a feasible antithrombotic regimen following stent implantation in patients who require OAC therapy.

Endothelial Recovery in Bare Metal Stents and Drug-Eluting Stents on a Single-Cell Level

[Figure: see text].

The biological responses and mechanisms of endothelial cells to magnesium alloy

Due to its good biocompatibility and degradability, magnesium alloy (Mg alloy) has shown great promise in cardiovascular stent applications. Rapid stent re-endothelialization is derived from migrated and adhered endothelial cells (ECs), which is an effective way to reduce late thrombosis and inhibit hyperplasia. However, fundamental questions regarding Mg alloy affecting migration and adhesion of ECs are not fully understood. Here, we evaluated the effects of Mg alloy on the ECs proliferation, adhesion and migration. A global gene expression profiling of ECs co-culturing with Mg alloy was conducted, and the adhesion- and migration-related genes were examined. We found that Mg alloy had no adverse effects on ECs viability but significantly affected ECs migration and adhesion. Co-cultured with Mg alloy extract, ECs showed contractive adhesion morphology and decreased motility, which was supported by the down-regulation of adhesion-related genes (Paxillin and Vinculin) and migration-related genes (RAC 1, Rho A and CDC 42). Accordingly, the re-endothelialization of Mg alloy stent was inhibited in vivo. Our results may provide new inspiration for improving the broad application of Mg alloy stents.

Impact of Coronary Calcification on Clinical Outcomes After Implantation of Newer-Generation Drug-Eluting Stents

Background

Percutaneous coronary intervention of calcified lesions was associated with worse outcomes in the era of bare‐metal and first‐generation drug‐eluting stents. Data on percutaneous coronary intervention of calcified lesions with newer‐generation drug‐eluting stents are scarce. Therefore, we investigated the impact of lesion calcification on clinical outcomes in patients undergoing percutaneous coronary intervention with a bioresorbable‐polymer sirolimus‐eluting stent or a durable‐polymer everolimus‐eluting stent.

Methods and Results

Patients (n=2361) from BIOFLOW II, IV, and V trials were categorized into moderate/severe versus none/mild lesion calcification by a core laboratory. End points were target‐lesion failure (TLF) (cardiac death, target‐vessel myocardial infarction, or target‐lesion revascularization) and probable/definite stent thrombosis at 2 years. The agreement in calcification assessment between the operator and the core laboratory was weak (weighted κ, 0.23). Patients with moderate/severe calcification (n=303; 16%) had higher TLF (13.5% versus 8.4%; P=0.003) and stent thrombosis rates (2.1% versus 0.2%; P<0.0001), whereas target‐lesion revascularization was not different between the groups (5.0% versus 3.9%; P=0.302). After adjustment, calcification did not emerge as an independent predictor of TLF (adjusted hazard ratio [aHR], 1.37; 95% CI, 0.89–2.08; P=0.148) but did for target‐vessel myocardial infarction (aHR, 1.66; 95% CI, 1.03–2.68; P=0.037). TLF rates were similar between bioresorbable‐polymer sirolimus‐eluting stent and durable‐polymer everolimus‐eluting stent (12.6% versus 15.4%, P=0.482) in moderate/severe calcification. In none/mild calcification, the bioresorbable‐polymer sirolimus‐eluting stent showed lower TLF (7.5% versus 10.3%, P=0.045).

Conclusions

With newer‐generation drug‐eluting stents, moderate/severe lesion calcification was not associated with more TLF after adjustment for the higher risk of patients with coronary calcification, whereas the rate of target‐vessel myocardial infarction was higher. The bioresorbable‐polymer sirolimus‐eluting stent and durable‐polymer everolimus‐eluting stent were equally effective and safe in calcified lesions.

Registration

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT01356888, NCT01939249, NCT02389946.

Outcomes of patients treated with a biodegradable-polymer sirolimus-eluting stent versus durable-polymer everolimus-eluting stents after rotational atherectomy

OBJECTIVE

To compare Orsiro biodegradable-polymer sirolimus-eluting stent (Orsiro BP-SES) with durable-polymer everolimus-eluting stent (DP-EES) regarding target lesion failure (TLF) after rotational atherectomy (RA), with a focus on small stents (diameter ≤ 3 mm) where Orsiro BP-SES has 60 µm strut thickness, while DP-EES remains with 81 µm strut thickness.

BACKGROUND

New-generation drug-eluting stent (DES) is superior to early-generation DES in all percutaneous coronary intervention (PCI) settings including RA. Recently, the Orsiro BP-SES was superior to a DP-EES in an all comer's population.

METHODS

Among patients who underwent RA at a single center, 121 were treated with Orsiro BP-SES and 164 with DP-EES (Promus and Xience). Those treated with other stent types, presenting with acute myocardial infarction or had a chronic total occlusion were excluded. Incidence of TLF was assessed.

RESULTS

After 2 years, the TLF rate in Orsiro BP-SES and DP-EES groups was 10% and 18%, respectively (adjusted HR 0.55, 95%CI 0.26-1.16, p = 0.115). The rate of TLF was significantly lower in small Orsiro BP-SES with ultra-thin struts as compared to DP-EES with the same diameters (adjusted HR 0.19, 95% CI 0.04-0.87, p = 0.032), driven by lower rates of clinically driven target lesion revascularization (log-rank p = 0.022). Age (p = 0.035), total stent length (p = 0.007) and diabetes mellitus (p = 0.011) emerged as independent predictors of TLF in the whole population.

CONCLUSION

In the whole cohort, Orsiro BP-SES and DP-EES had comparable rates of long-term TLF after RA. In the small stent subgroup, the Orsiro BP-SES with ultra-thin struts showed significant lower rate of TLF at 2 years.

Eruptive Calcified Nodules as a Potential Mechanism of Acute Coronary Thrombosis and Sudden Death

BACKGROUND

Calcified nodule (CN) has a unique plaque morphology, in which an area of nodular calcification causes disruption of the fibrous cap with overlying luminal thrombus. CN is reported to be the least frequent cause of acute coronary thrombosis, and the pathogenesis of CN has not been well studied.

OBJECTIVES

The purpose of this study is to provide a comprehensive morphologic assessment of the CN in addition to providing an evolutionary perspective as to how CN causes acute coronary thrombosis in patients with acute coronary syndromes.

METHODS

A total of 26 consecutive CN lesions from 25 subjects from our autopsy registry were evaluated. Detailed morphometric analysis was performed to understand the plaque characteristics of CN and nodular calcification.

RESULTS

The mean age was 70 years, with a high prevalence of diabetes and chronic kidney disease. CNs were equally distributed between men and women, with 61.5% of CNs found in the right coronary artery (n = 16), mainly within its mid-portion (56%). All CNs demonstrated surface nonocclusive luminal thrombus, consisting of multiple nodular fragments of calcification, protruding and disrupting the overlying fibrous cap, with evidence of endothelial cell loss. The degree of circumferential sheet calcification was significantly less in the culprit section (89° [interquartile range: 54° to 177°]) than in the adjacent proximal (206° [interquartile range: 157° to 269°], p = 0.0034) and distal (240° [interquartile range: 178° to 333°], p = 0.0004) sections. Polarized picrosirius red staining showed the presence of necrotic core calcium at culprit sites of CNs, whereas collagen calcium was more prevalent at the proximal and distal regions of CNs.

CONCLUSIONS

Our study suggests that fibrous cap disruption in CN with overlying thrombosis is initiated through the fragmentation of necrotic core calcifications, which is flanked-proximally and distally-by hard, collagen-rich calcification in coronary arteries, which are susceptible to mechanical stress.

Risk prediction of in-stent restenosis among patients with coronary drug-eluting stents: current clinical approaches and challenges

Introduction: In-stent restenosis (ISR) has been one of the biggest limitations to the success of percutaneous coronary intervention for the treatment of coronary artery disease (CAD). The introduction of drug-eluting stent (DES) was a revolution in the treatment of CAD because these devices drastically reduced ISR to very low levels (<5%). Subsequently, newer generation DES treatments have overcome the drawbacks of first-generation DES, i.e. delayed endothelialization, and late stent thrombosis. However, the issue of late ISR, including neoatherosclerosis after DES implantation especially in high-risk patients and complex lesions, still exists as a challenge to be overcome.Areas covered: We discuss the mechanisms of ISR development including neoatherosclerosis, past and current clinical status of ISR, and methods to predict and overcome this issue from pathological and clinical points of view.Expert opinion: The initial drawbacks of first-generation DES, such as delayed endothelial healing and subsequent risk of late stent thrombosis, have been improved upon by the current generation DES. To achieve better long-term clinical outcomes, further titration of drug-release and polymer degradation profile, strut thickness as well as material innovation are needed.

Cardiac outcomes in patients with acute coronary syndrome attributable to calcified nodule

BACKGROUND AND AIMS

Calcified nodule (CN) is an eruptive calcified mass causing acute coronary syndrome (ACS). Since coronary calcification is associated with an elevated cardiac event's risk, ACS attributable to CN may exhibit worse clinical outcome following percutaneous coronary intervention (PCI).

METHODS

We retrospectively analyzed 657 ACS patients receiving PCI with newer-generation drug-eluting stent (DES) implantation under intravascular ultrasound (IVUS) guidance. CN was defined as (1) protruding calcification with its irregular surface and (2) the presence of calcification at adjacent proximal and distal segments. The primary endpoint was a composite of major adverse cardiac event [MACE = cardiac death + ACS recurrence + target lesion revascularization (TLR)].

RESULTS

CN was identified in 5.3% (=35/657) of the study subjects. CN patients were more likely to have coronary risk factors including hypertension (p = 0.005), chronic kidney disease (p < 0.001), maintenance hemodialysis (p < 0.001) and a history of PCI (p < 0.001). During the observational period (median = 1304 days), CN was associated with an increased risk of MACE (HR = 7.68, 95%CI = 4.61-12.80, p < 0.001), ACS recurrence (HR = 12.32, 95%CI = 6.05-25.11, p < 0.001) and TLR (HR = 10.48, 95%CI = 5.80-18.94, p < 0.001). These cardiac risks related to CN were consistently observed by Cox proportional hazards model (MACE: p < 0.001, ACS recurrence: p < 0.001, TLR: p < 0.001) and a propensity score-matched cohort analysis (MACE: p = 0.002, ACS recurrence: p = 0.01, TLR: p = 0.005). Of note, over 80% of TLR at the CN lesion was driven by its re-appearance within the implanted DES.

CONCLUSIONS

ACS patients attributable to CN have an increased risk of ACS recurrence and TLR, mainly driven by the continuous growth and protrusion of the calcified mass.

Co-Registration of Peripheral Atherosclerotic Plaques Assessed by Conventional CT Angiography, MicroCT and Histology in Patients with Chronic Limb Threatening Ischaemia

OBJECTIVE

To co-register conventional computed tomography angiography (CTA), with ex vivo micro-computed tomography (microCT) and histology of popliteal atherosclerotic plaques. Improving the non-invasive imaging capabilities may be valuable to advance patient care with peripheral arterial obstructive disease towards lesion and individual based treatment.

METHODS

In this prospective observational study, 12 popliteal arteries from 11 symptomatic patients who had undergone transfemoral amputations for chronic limb threatening ischaemia and who had pre-operative CTA, were analysed ex vivo by microCT and histology. A total of 353 histological cross sections were co-registered with microCT and CTA, and classified as: lipid rich (LP, n = 26), fibrous (FP, n = 80), or calcific (CP, n = 247) plaques. CTA and microCT plaque density was calculated in 791 regions of interest as Hounsfield units (HU).

RESULTS

CTA and microCT could identify plaque components that were confirmed by histology such as fibrous tissue (FP), lipid pool/core (LP), and calcification (CP). MicroCT densities were 77.8 HU for FP (IQR 52.8, 129.5 HU), -28.4 HU for LP (IQR -87.1, 13.2 HU), and 3826.0 HU for CP (IQR 2989.0, 4501.0 HU). CTA densities of the three components of the plaque were: 78.0 HU for FP (IQR 59.5, 119.8 HU), 32.5 HU for LP (IQR 15.0, 42 HU), and 641.5 HU for CP (IQR 425.8, 1135 HU). The differences were statistically significant between the HU densitometric characteristics among the three groups (p < .0001) for both imaging modalities. Overall, microCT performed better diagnostically than conventional CTA for the three types of plaques: areas under the receiving operator characteristics curve were greater for microCT than CTA for FP (0.97 vs. 0.90), for LP (0.88 vs. 0.67), and for CP (0.97 vs. 0.90).

CONCLUSION

CTA and microCT can be used to identify histological atherosclerotic plaque components, with better diagnostic performance for microCT. This study demonstrates the feasibility of using microCT to assess plaque morphology lesions in a manner that approaches histology thus becoming a useful tool for ex vivo assessment of atherosclerosis and towards lesion based treatment.

Cracking (the code of) coronary artery calcification to win the last battle of percutaneous coronary intervention: still in the middle of a rocky road

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