Very late vasomotor responses and gene expression with bioresorbable scaffolds and metallic drug-eluting stents

OBJECTIVES

To investigate the long-term vasomotor response and inflammatory changes in Absorb bioresorbable vascular scaffold (BVS) and metallic drug-eluting stent (DES) implanted artery.

BACKGROUND

Clinical evidence has demonstrated that compared to DES, BVS is associated with higher rates of target lesion failure. However, it is not known whether the higher event rates observed with BVS are related to endothelial dysfunction or inflammation associated with polymer degradation.

METHODS

Ten Absorb BVS and six Xience V DES were randomly implanted in the main coronaries of six nonatherosclerotic swine. At 4-years, vasomotor response was evaluated in vivo by quantitative coronary angiography response to intracoronary infusion of Ach and ex vivo by the biomechanical response to prostaglandin F2-α (PGF2-α), substance P and bradykinin and gene expression analysis.

RESULTS

Absorb BVS implanted arteries showed significantly restored vasoconstrictive responses after Ach compared to in-stent Xience V. The contractility of Absorb BVS treated segments induced by PGF2-α was significantly greater compared to Xience V treated segments and endothelial-dependent vasorelaxation was greater with Absorb BVS compared to Xience V. Gene expression analyses indicated the pro-inflammatory lymphotoxin-beta receptor (LTβR) signaling pathway was significantly upregulated in arteries treated with a metallic stent compared to Absorb BVS treated arterial segments.

CONCLUSIONS

At 4 years, arteries treated with Absorb BVS compared with Xience V, demonstrate significantly greater restoration of vasomotor responses. Genetic analysis suggests mechanobiologic reparation of Absorb BVS treated arteries at 4 years as opposed to Xience V treated vessels.

Bioresorbable vascular scaffolds versus everolimus-eluting stents: a biomechanical analysis of the ABSORB III Imaging substudy

AIMS

The Absorb bioresorbable vascular scaffold (BVS) has high rates of target lesion failure (TLF) at three years. Low wall shear stress (WSS) promotes several mechanisms related to device TLF. We investigated the impact of BVS compared to XIENCE V (XV) on coronary WSS after device deployment.

METHODS AND RESULTS

In the prospective, randomised, controlled ABSORB III Imaging study (BVS [n=77] or XV [n=36]), computational fluid dynamics were performed on fused angiographic and intravascular ultrasound (IVUS) images of post-implanted vessels. Low WSS was defined as <1 Pa. There were no differences in demographics, clinical risks, angiographic reference vessel diameter or IVUS minimal lumen diameter between BVS and XV patients. A greater proportion of vessels treated with BVS compared to XV demonstrated low WSS across the whole device (BVS: 17/77 [22%] vs XV: 2/36 [6%], p<0.029). Compared to XV, BVS demonstrated lower median circumferential WSS (1.73 vs 2.21 Pa; p=0.036), outer curvature WSS (p=0.026), and inner curvature WSS (p=0.038). Similarly, BVS had lower proximal third WSS (p=0.024), middle third WSS (p=0.047) and distal third WSS (p=0.028) when compared to XV. In a univariable logistic regression analysis, patients who received BVS were 4.8 times more likely to demonstrate low WSS across the scaffold/stent when compared to XV patients. Importantly, in a multivariable linear regression model, hypertension (beta: 0.186, p=0.023), lower contrast frame count velocity (beta: -0.411, p<0.001), lower post-stent residual plaque burden (beta: -0.338, p<0.001), lower % underexpanded frames (beta: -0.170, p=0.033) and BVS deployment (beta: 0.251, p=0.002) remained independently associated with a greater percentage of stented coronary vessel areas exposed to low WSS.

CONCLUSIONS

In this randomised controlled study, the Absorb BVS was 4.8 times more likely than the XV metallic stent to demonstrate low WSS. BVS implantation, lower blood velocity and lower residual post-stent plaque burden were independently associated with greater area of low WSS.

Overlapping Drug-Eluting Stent Is Associated with Increased Definite Stent Thrombosis and Revascularization: Results from 15,561 Patients in the AUTHENTIC Study

PURPOSE

This study was to analyze the incidence of definite stent thrombosis (ST) after the implantation of drug-eluting stents (DESs) and cutoff value of overlapping length for predicting definite ST. An overlapping stent is associated with a high rate of clinical events after DES implantation compared with a non-overlapping stent. However, the rates of definite ST and clinical outcomes from a large patient population remain underreported.

METHODS

A total of 15,561 patients with 24,183 lesions who underwent DES implantation from January 2005 to February 2017 were retrospectively included in 5 tertiary hospitals in China. The main endpoint was the incidence of definite ST after procedures.

RESULTS

With a median of 1932 (IQR = 1194-2929) days, clinical follow-up was available in 7484 patients in the overlap group and in 8077 patients in the non-overlap group. The rates of definite ST were 3.1% in the overlap group and 1.2% in the non-overlap group (HR: 2.67 (95% CI: 2.11-3.38), p < 0.001). Of the 24,183 treated lesions, the incidences of definite ST were 2.4% in the overlap group and 0.9% in the non-overlap group (HR: 2.96 (95% CI: 2.38-3.69), p < 0.001). Stent overlap was associated with a higher rate of target lesion revascularization (TLR) (9.4%) compared with stent non-overlap (6.4%, p < 0.001). The length of overlapping stent ≥ 2.93 mm strongly correlated with definite ST.

CONCLUSION

The present study shows that overlapping DES increases definite ST and revascularization in patients during long-term follow-up. In addition, the longer overlapping zone was associated with worse clinical outcomes.

Optical coherence tomography predictors of target vessel myocardial infarction after provisional stenting in patients with coronary bifurcation disease

BACKGROUND

Provisional side branch (SB) stenting is correlated with target vessel myocardial infarction (TVMI) in patients with coronary bifurcation lesions. However, the mechanisms underlying this association remain unknown.

OBJECTIVES

To determine the correlation between SB lesion length with vulnerable plaques and TVMI using optical coherence tomography (OCT).

BACKGROUND

The correlation between SB lesion length with vulnerable plaques and TVMI is unknown.

METHODS

A total of 405 patients with 405 bifurcation lesions who underwent preprocedure OCT imaging of both the main vessel (MV) and the SB were enrolled. Patients were divided into long SB lesion (SB lesion length ≥10 mm) and short SB lesion (SB lesion length <10 mm) groups according to quantitative coronary analysis; they were also stratified by the presence of vulnerable plaques identified by OCT. The primary endpoint was the occurrence of TVMI after provisional stenting at 1-year follow-up.

RESULTS

In total, 178 (43.9%) patients had long SB lesions. Vulnerable plaques were predominantly localized in the MV and were more frequently in the long SB lesion group (42.7%) than in the short SB lesion group (24.2%, p < .001). At 1-year follow-up after provisional stenting, there were 31 (7.7%) TVMIs, with 21 (11.8%) in the long SB lesion group and 10 (4.4%) in the short SB lesion group (p = .009). Multivariate regression analysis showed that long SB lesion length (p = .011), absence of vulnerable plaques in the polygon of confluence (p = .001), and true coronary bifurcation lesions (p = .004) were the three independent factors of TVMI.

CONCLUSIONS

The presence of long SB lesion with MV vulnerable plaques predicts the increased risk of TVMI after provisional stenting in patients with true coronary bifurcation lesions. Further studies are warranted to identify the best stenting techniques for coronary bifurcation lesions with long SB lesions.

One-year efficacy and safety of everolimus-eluting bioresorbable scaffolds in the setting of acute myocardial infarction

BACKGROUND AND OBJECTIVES

This study sought to compare clinical outcomes between bioresorbable scaffolds (BRS) and durable polymer everolimus-eluting metallic stents (DP-EES) in patients with acute myocardial infarction (AMI) undergoing successful percutaneous coronary intervention (PCI).

METHODS

From March 2016 to October 2017, 952 patients with AMI without cardiogenic shock undergoing successful PCI with BRS (n = 136) or DP-EES (n = 816) were enrolled from a multicenter, observational Korea Acute Myocardial Infarction Registry.

RESULTS

In the crude population, there was no significant difference in the 1-year rate of device-oriented composite endpoint (DOCE) and device thrombosis between the BRS and DP-EES groups (2.2% vs. 4.8%, hazard ratio [HR] 0.43, 95% confidence interval [CI] 0.13-1.41, p = 0.163; 0.7% vs. 0.5%, HR 1.49, 95% CI 0.16-13.4, p = 0.719, respectively). BRS implantation was opted in younger patients (53.7 vs. 62.6 years, p < 0.001) with low-risk profiles, and intravascular image-guided PCI was more preferred in the BRS group (60.3% vs. 27.2%, p < 0.001).

CONCLUSIONS

At 1-year follow-up, no differences in the rate of DOCE and device thrombosis were observed between patients with AMI treated with BRS and those treated with DP-EES. Our data suggest that imaging-guided BRS implantation in young patients with low risk profiles could be a reasonable strategy in the setting of AMI.

Left Main Coronary Interventions: A Practical Guide

Coronary artery bypass surgery has been the accepted treatment for left main coronary artery disease for over 50 years. Balloon angioplasty was later used then abandoned because of deaths likely due to restenosis or thrombotic occlusion. However, rapid innovations in drug-eluting stent designs leading to more biocompatible thin strut platforms with optimal drug elution profiles and further advances in modern pharmacotherapy involving potent P2Y₁₂ inhibitors combined with utilization of intracoronary imaging and physiologic assessment for procedural planning and optimization have transformed percutaneous interventions into successful alternatives to coronary artery bypass graft surgery (CABG) in selected LM anatomic territories. Herein, we provide an evidence-based practical guide on how to approach and perform LM percutaneous interventions (PCI).

Efficacy and safety of drug-eluting stents in elderly patients: A meta-analysis of randomized trials

BACKGROUND

Current guidelines recommend newer generation drug-eluting stents (DES) over bare-metal stents (BMS) in patients with ischemic heart disease. However, there is no age-specific recommendation in elderly patients.

METHODS

Meta-analysis was performed of 6 randomized studies enrolling 5,042 elderly patients who underwent percutaneous coronary intervention (PCI) with stent implantation (DES, n = 2,579; BMS, n = 2,463).

RESULTS

Combined data indicated a significant reduction in major adverse cardiovascular events (MACEs) with use of DES (odds ratio [OR] 0.56, 95% confidence interval [CI] 0.44-0.71, p < 0.001). Moreover, use of DES was associated with a significantly lower incidence of myocardial infarction (OR 0.54, 95% CI 0.36-0.81, p = 0.003) and repeat revascularization (OR 0.44, 95% CI 0.31-0.62, p < 0.001), was compared to that with the use of BMS. Stent thrombosis and bleeding complication rates were not significantly different between groups. In a subgroup meta-analysis, short duration (1 or 6 months) dual antiplatelet therapy (DAPT) was associated with a significantly lower MACE rate (OR 0.49, 95% CI 0.34-0.80; p = 0.003) in elderly patients who underwent PCI with everolimuseluting stent implantation, compared with that using long duration DAPT.

CONCLUSIONS

This meta-analysis provides clinically relevant evidence that DES rather than BMS should be selected for elderly patients.

Long-term safety of bioresorbable scaffolds: insights from a network meta-analysis including 91 trials

AIMS

The aim of this study was to investigate the long-term safety and efficacy of biodegradable scaffolds and metallic stents.

METHODS AND RESULTS

We analysed a total of 91 randomised controlled trials with a mean follow-up of 3.7 years in 105,842 patients which compared two or more coronary metallic stents or biodegradable scaffolds and reported the long-term clinical outcomes (≥2 years). Network meta-analysis showed that patients treated with the Absorb bioresorbable vascular scaffold (BVS) had a significantly higher risk of definite or probable scaffold thrombosis (ScT) compared to those treated with metallic DES. The risk of very late ScT was highest with the Absorb BVS among comparators. Pairwise conventional meta-analysis demonstrated that the elevated risk of ScT with Absorb BVS compared to cobalt-chromium everolimus-eluting stents was consistent across the time points of ≤30 days (early), 31 days - 1 year (late) and >1 year (very late) ScT. In addition, target lesion failure rates were significantly higher in the Absorb BVS cohort, driven by both increased risk of target vessel myocardial infarction and ischaemia-driven target lesion revascularisation.

CONCLUSIONS

Absorb BVS implantation was associated with increased risk of long-term and very late ScT compared to current-generation metallic DES. The risk of ScT occurred with a rising trend beyond one year.

Volume brings value

What the article teaches The article highlights the competency of high volume operators across institutions that despite moving to lower volume centers retain their good clinical outcomes. How it will impact practice Although current U.S. based guidelines suggest a volume of at least 50 PCIs annually for operators to retain clinical competency this estimate may be a poor index to guarantee optimal clinical outcomes. What new research/study would help answer the question New studies using a comprehensive definition to define an experienced operator from the Asia-Pacific-a geographic area that has pioneered in complex coronary interventions-need to elute on the threshold of adequate clinical competency stratified according to clinical complexity.

Low Coronary Wall Shear Stress Is Associated With Severe Endothelial Dysfunction in Patients With Nonobstructive Coronary Artery Disease

OBJECTIVES

This study investigated the relationship between low wall shear stress (WSS) and severe endothelial dysfunction (EDFx).

BACKGROUND

Local hemodynamic forces such as WSS play an important role in atherogenesis through their effect on endothelial cells. The study hypothesized that low WSS independently predicts severe EDFx in patients with coronary artery disease (CAD).

METHODS

Forty-four patients with CAD underwent coronary angiography, fractional flow reserve, and endothelial function testing. Segments with >10% vasoconstriction after acetylcholine (Ach) infusion were defined as having severe EDFx. WSS, calculated using 3-dimensional angiography, velocity measurements, and computational fluid dynamics, was defined as low (<1 Pa), intermediate (1 to 2.5 Pa), or high (>2.5 Pa).

RESULTS

Median age was 52 years, 73% were women. Mean fractional flow reserve was 0.94 ± 0.06. In 4,510 coronary segments, median WSS was 3.67 Pa. A total of 24% had severe EDFx. A higher proportion of segments with low WSS had severe EDFx (71%) compared with intermediate WSS (22%) or high WSS (23%) (p < 0.001). Segments with low WSS demonstrated greater vasoconstriction in response to Ach than did intermediate or high WSS segments (-10.7% vs. -2.5% vs. +1.3%, respectively; p < 0.001). In a multivariable logistic regression analysis, female sex (odds ratio [OR]: 2.44; p = 0.04), diabetes (OR: 5.01; p = 0.007), and low WSS (OR: 9.14; p < 0.001) were independent predictors of severe EDFx.

CONCLUSIONS

In patients with nonobstructive CAD, segments with low WSS demonstrated more vasoconstriction in response to Ach than did intermediate or high WSS segments. Low WSS was independently associated with severe EDFx.

Intravascular Ultrasound Versus Angiography-Guided Drug-Eluting Stent Implantation: The ULTIMATE Trial

BACKGROUND

Intravascular ultrasound (IVUS)-guided drug-eluting stent (DES) implantation is associated with fewer major adverse cardiovascular events compared with angiography guidance for patients with individual lesion subset. However, the beneficial effect on major adverse cardiovascular event outcome of IVUS guidance over angiography guidance in all-comers who undergo DES implantation still remains understudied.

OBJECTIVES

This study aimed to determine the benefits of IVUS guidance over angiography guidance during DES implantation in all-comer patients.

METHODS

A total of 1,448 all-comer patients who required DES implantation were randomly assigned (1:1 ratio) to either an IVUS guidance or angiography guidance group. The primary endpoint was target-vessel failure (TVF) at 12 months, including cardiac death, target-vessel myocardial infarction, and clinically driven target-vessel revascularization (TVR). The procedure was defined as a success if all IVUS-defined optimal criteria were met.

RESULTS

At 12 months follow-up, 60 TVFs (4.2%) occurred, with 21 (2.9%) in the IVUS group and 39 (5.4%) in the angiography group (hazard ratio [HR]: 0.530; 95% confidence interval [CI]: 0.312 to 0.901; p = 0.019). In the IVUS group, TVF was recorded in 1.6% of patients with successful procedures, compared with 4.4% in patients who failed to achieve all optimal criteria (HR: 0.349; 95% CI: 0.135 to 0.898; p = 0.029). The significant reduction of clinically driven target-lesion revascularization or definite stent thrombosis (HR: 0.407; 95% CI: 0.188 to 0.880; p = 0.018) based on lesion-level analysis by IVUS guidance was not achieved when the patient-level analysis was performed.

CONCLUSIONS

The present study demonstrates that IVUS-guided DES implantation significantly improved clinical outcome in all-comers, particularly for patients who had an IVUS-defined optimal procedure, compared with angiography guidance. (Intravascular Ultrasound Guided Drug Eluting Stents Implantation in "All-Comers" Coronary Lesions [ULTIMATE]; NCT02215915).

Discordance Between Fractional Flow Reserve and Coronary Flow Reserve: Insights From Intracoronary Imaging and Physiological Assessment

OBJECTIVES

The aim of this study was to investigate the epicardial and microvascular substrates associated with discordances between fractional flow reserve (FFR) and coronary flow reserve (CFR) values.

BACKGROUND

Discordances between FFR and CFR remain poorly characterized.

METHODS

FFR, hyperemic stenosis resistance (HSR), and intravascular ultrasound were performed as indexes of epicardial function and CFR and hyperemic microvascular resistance (HMR) as measures of microvascular function in 94 patients with moderate coronary stenosis. Maximal plaque burden (PB_max), HSR, and HMR were calculated in 4 quadrants based on values of FFR ≤0.80 and CFR ≤2.0 as follows: concordant normal (preserved FFR and CFR), concordant abnormal (low FFR and CFR), discordant low FFR and preserved CFR, and discordant preserved FFR and low CFR.

RESULTS

Sixty-four patients (68%) had concordant FFR and CFR findings, and 30 patients (32%) had discordant FFR and CFR. Compared with patients with preserved FFR and CFR, those with low FFR and CFR had higher PB_max (p = 0.003), higher HSR (p < 0.001), and similar HMR. Among patients with preserved FFR, those with reduced CFR had similar PB_max and HSR but a trend toward higher HMR (p = 0.058) compared with patients with preserved CFR. Among patients with reduced FFR, those with preserved CFR had lower PB_max (p = 0.004), a trend toward lower HSR (p = 0.065), and lower HMR (p = 0.03) compared with patients with reduced CFR. Furthermore, compared with patients with preserved FFR and low CFR, those with low FFR and preserved CFR had higher HSR (p = 0.022) but lower HMR (p = 0.003).

CONCLUSIONS

In patients with moderate coronary stenosis, preserved FFR and low CFR is associated with increased microvascular resistance, while low FFR and preserved CFR has modest epicardial stenosis and preserved microvascular function.

Performance of J-CTO and PROGRESS CTO Scores in Predicting Angiographic Success and Long-term Outcomes of Percutaneous Coronary Interventions for Chronic Total Occlusions

Patient selection for and predicting clinical outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) remain challenging. We hypothesized that both J-CTO (Multicenter Chronic Total Occlusion Registry of Japan) and PROGRESS CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) scores will predict not only angiographic success but also long-term clinical outcomes of the patients who underwent PCI of CTO. Of 325 CTO PCIs performed at 2 Emory University hospitals from January 2012 to August 2015, 249 patients with complete baseline clinical, angiographic and follow-up data, were included in this analysis. Major adverse cardiovascular events (MACEs) consisted of a composite of death, myocardial infarction, and target vessel revascularization. Mean age was 63 ± 11 years old and mean follow-up was 19.8 ± 13.1 months. Angiographic success rates increased from 74.5% in 2012 to 85.7% in 2015. Greater J-CTO and PROGRESS CTO scores were not only associated with lower likelihood of angiographic success but also higher rates of long-term MACE. Compared with the scores of 0 to 2, J-CTO and PROGRESS CTO scores of ≥3 were associated with higher MACE. Multivariable analysis demonstrated that PROGRESS CTO scores of ≥3, male sex, and peripheral vascular disease were independent predictors of MACE. In conclusion, J-CTO and PROGRESS CTO scores are useful in predicting procedural success. In addition, the PROGRESS CTO score, and to a lesser degree J-CTO score, have predictive value for long-term outcomes in patients who underwent CTO PCI.

Computational estimation of the severity of coronary lesions with intravascular ultrasound images: a pilot study

The fast and accurate hemodynamic functional assessment of the coronary vasculature is of utmost importance in clinical practice due to the fact that Cardiovascular Diseases have become the leading cause of death globally. In this work we propose a novel method that combines two of the most efficient methods of hemodynamic status assessment of coronary arteries, Intravascular UtraSound and virtual Functional Assessment Index, an index that correlates well to the measured Fractional Flow Reserve. One Left Anterior Descending segment was reconstructed both in a straight manner (using only IVUS images) as well as using the actual 3D geometry of the vessel (using IvUS images combined with the respective coronary angiographic images [2]). The generated vFAI values were almost identical (Straight=0.80, 3D=0.79), presenting a relative error of 1.27%, thus proving the efficacy of the proposed method. We also calculated the Endothelial Shear Stress for the two models under rest (i.e. flow rate of 1 ml/s), observing a similar trend throughout the artery, but with a statistically important relative error of 13.49%, as expected.

High wall shear stress and high-risk plaque: an emerging concept

In recent years, there has been a significant effort to identify high-risk plaques in vivo prior to acute events. While number of imaging modalities have been developed to identify morphologic characteristics of high-risk plaques, prospective natural-history observational studies suggest that vulnerability is not solely dependent on plaque morphology and likely involves additional contributing mechanisms. High wall shear stress (WSS) has recently been proposed as one possible causative factor, promoting the development of high-risk plaques. High WSS has been shown to induce specific changes in endothelial cell behavior, exacerbating inflammation and stimulating progression of the atherosclerotic lipid core. In line with experimental and autopsy studies, several human studies have shown associations between high WSS and known morphological features of high-risk plaques. However, despite increasing evidence, there is still no longitudinal data linking high WSS to clinical events. As the interplay between atherosclerotic plaque, artery, and WSS is highly dynamic, large natural history studies of atherosclerosis that include WSS measurements are now warranted. This review will summarize the available clinical evidence on high WSS as a possible etiological mechanism underlying high-risk plaque development.

The edge vascular response following implantation of the Absorb everolimus-eluting bioresorbable vascular scaffold and the XIENCE V metallic everolimus-eluting stent. First serial follow-up assessment at six months and two years: insights from the first-in-man ABSORB Cohort B and SPIRIT II trials

AIMS

To assess serially the edge vascular response (EVR) of a bioresorbable vascular scaffold (BVS) compared to a metallic everolimus-eluting stent (EES).

METHODS AND RESULTS

Non-serial evaluations of the Absorb BVS at one year have previously demonstrated proximal edge constrictive remodelling and distal edge changes in plaque composition with increase of the percent fibro-fatty (FF) tissue component. The 5 mm proximal and distal segments adjacent to the implanted devices were investigated serially with intravascular ultrasound (IVUS), post procedure, at six months and at two years, from the ABSORB Cohort B1 (n=45) and the SPIRIT II (n=113) trials. Twenty-two proximal and twenty-four distal edge segments were available for analysis in the ABSORB Cohort B1 trial. In the SPIRIT II trial, thirty-three proximal and forty-six distal edge segments were analysed. At the 5-mm proximal edge, the vessels treated with an Absorb BVS from post procedure to two years demonstrated a lumen loss (LL) of 6.68% (-17.33; 2.08) (p=0.027) with a trend toward plaque area increase of 7.55% (-4.68; 27.11) (p=0.06). At the 5-mm distal edge no major changes were evident at either time point. At the 5-mm proximal edge the vessels treated with a XIENCE V EES from post procedure to two years did not show any signs of LL, only plaque area decrease of 6.90% (-17.86; 4.23) (p=0.035). At the distal edge no major changes were evident with regard to either lumen area or vessel remodelling at the same time point.

CONCLUSIONS

The IVUS-based serial evaluation of the EVR up to two years following implantation of a bioresorbable everolimus-eluting scaffold shows a statistically significant proximal edge LL; however, this finding did not seem to have any clinical implications in the serial assessment. The upcoming imaging follow-up of the Absorb BVS at three years is anticipated to provide further information regarding the vessel wall behaviour at the edges.

Comprehensive Assessment of Coronary Plaque Progression With Advanced Intravascular Imaging, Physiological Measures, and Wall Shear Stress: A Pilot Double-Blinded Randomized Controlled Clinical Trial of Nebivolol Versus Atenolol in Nonobstructive Coronary Artery Disease

Background

We hypothesized that nebivolol, a β‐blocker with nitric oxide–mediated activity, compared with atenolol, a β‐blocker without such activity, would decrease oxidative stress and improve the effects of endothelial dysfunction and wall shear stress (WSS), thereby reducing atherosclerosis progression and vulnerability in patients with nonobstructive coronary artery disease.

Methods and Results

In this pilot double‐blinded randomized controlled trial, 24 patients treated for 1 year with nebivolol 10 mg versus atenolol 100 mg plus standard medical therapy underwent baseline and follow‐up coronary angiography with assessments of inflammatory and oxidative stress biomarkers, microvascular function, endothelial function, and virtual histology intravascular ultrasound. WSS was calculated from computational fluid dynamics. Virtual histology intravascular ultrasound segments were assessed for vessel volumetrics and remodeling. There was a trend toward more low‐WSS segments in the nebivolol cohort (P=0.06). Low‐WSS regions were associated with greater plaque progression (P<0.0001) and constrictive remodeling (P=0.04); conversely, high‐WSS segments demonstrated plaque regression and excessive expansive remodeling. Nebivolol patients had decreased lumen and vessel areas along with increased plaque area, resulting in more constrictive remodeling (P=0.002). There were no significant differences in biomarker levels, microvascular function, endothelial function, or number of thin‐capped fibroatheromas per vessel. Importantly, after adjusting for β‐blocker, low‐WSS segments remained significantly associated with lumen loss and plaque progression.

Conclusion

Nebivolol, compared with atenolol, was associated with greater plaque progression and constrictive remodeling, likely driven by more low‐WSS segments in the nebivolol arm. Both β‐blockers had similar effects on oxidative stress, microvascular function, and endothelial function.

Clinical Trial Registration

URL: https://clinicaltrials.gov/. Unique identifier: NCT01230892.

Biocorrodible metals for coronary revascularization: Lessons from PROGRESS-AMS, BIOSOLVE-I, and BIOSOLVE-II

The impetus for developing drug-eluting bioresorbable scaffolds (BRS) has been driven by the need for elastic and transient platforms instead of stiff and permanent metallic implants in diseased coronary anatomies. This endeavor would prevent acute recoil or occlusion, allow sealing of post-procedural dissections following acute barotrauma, provide inhibition of in-segment restenosis through efficient drug-elution and would further prepare the vessel to enter a reparative phase following scaffold resorption. Biocorrodible metallic platforms have been introduced as alternatives to bioresorbable polymeric scaffolds for the treatment of significant atherosclerosis and in view of the body of evidence derived from recent clinical trials we elaborate on the clinical safety and efficacy of these devices in interventional cardiology.

Bioresorbable polymeric scaffolds for coronary revascularization: Lessons learnt from ABSORB III, ABSORB China, and ABSORB Japan

Bioresorbable polymers and biocorrodible metals are the latest developments in biodegradable materials used in interventional cardiology for the mechanical treatment of coronary atherosclerosis. Poly-L-lactic acid is the most frequently used bioresorbable polymer and initial evidence of feasibility, efficacy and clinical safety following deployment of polymer-based platforms was gained after completion of the first-in-man longitudinal ABSORB registries, Cohorts A and B and ABSORB Extend.

In these studies, the biologic interaction of the first-generation Absorb Bioresorbable Vascular Scaffold (BVS) (Abbott Vascular, SC, Calif., US) with the underlying vascular tissue was evaluated in vivo with multiple imaging modalities such as intravascular ultrasound (IVUS), virtual histology-IVUS, IVUS-palpography, optical coherence tomography as well as ex vivo with coronary computed tomography. Efficacy measures following this in vivo multi-imaging assessment as well as clinical safety were comparable with current generation drug-eluting stents (DES) (Abbott Vascular, SC, Calif., US) in non-complex lesions over a 3-year follow-up. Furthermore, novel properties of functional and anatomic restoration of the vessel wall during the late phases of resorption and vascular healing were observed transforming the field of mechanical treatment of atherosclerosis from delivering only acute revascularization to additionally enable late repair and subsequent restoration of a more physiologic underlying vascular tissue.

Despite the sufficient evidence and the subsequent Conformité Européenne mark approval of the first fully biodegradable scaffold (Absorb BVS) in 2012 for revascularizing non-complex lesions, the paucity of randomized comparisons of fully bioresorbable scaffolds (BRS) with metallic DES in a “real-world” clinical setting raised controversies among the interventional community for the merit of these technologies. Only recently, results from international large-scale randomized trials from the United States (U.S.), China and Japan were revealed.

Herein we provide a comprehensive overview of the ABSORB III, ABSORB China and ABSORB Japan studies demonstrating the consistent non-inferiority in clinical safety and efficacy measures of the Absorb BVS vs. current generation DES.

Comparison of intravascular ultrasound guided versus angiography guided drug eluting stent implantation: a systematic review and meta-analysis

Background

Intravascular ultrasound (IVUS) can be a useful tool during drug-eluting stents (DES) implantation as it allows accurate assessment of lesion severity and optimal treatment planning. However, numerous reports have shown that IVUS guided percutaneous coronary intervention is not associated with improved clinical outcomes, especially in non-complex patients and lesions.

Methods

We searched the literature in Medline, the Cochrane Library, and other internet sources to identify studies that compare clinical outcomes between IVUS-guided and angiography-guided DES implantation. Random-effects model was used to assess treatment effect.

Results

Twenty eligible studies with a total of 29,068 patients were included in this meta-analysis. The use of IVUS was associated with significant reductions in major adverse cardiovascular events (MACE, odds ratios [OR] 0.77, 95 % confidence intervals [CI] 0.71-0.83, P < 0.001), death (OR 0.62, 95 % CI 0.54-0.71, p < 0.001), and stent thrombosis (OR 0.59, 95 % CI: 0.47-0.73, P < 0.001). The benefit was also seen in the repeated analysis of matched and randomized studies. In stratified analysis, IVUS guidance appeared to be beneficial not only in patients with complex lesions or acute coronary syndromes (ACS) but also patients with mixed lesions or presentations (MACE: OR 0.69, 95 % CI: 0.60-0.79, p < 0.001, OR 0.81, 95 % CI 0.74-0.90, p < 0.001, respectively). By employing meta-regression analysis, the benefit of IVUS is significantly pronounced in patients with complex lesions or ACS with respect to death (p = 0.048).

Conclusions

IVUS guidance was associated with improved clinical outcomes, especially in patients with complex lesions admitted with ACS. Large, randomized clinical trials are warranted to identify populations and lesion characteristics where IVUS guidance would be associated with better outcomes.

Computational fluid dynamics applied to virtually deployed drug-eluting coronary bioresorbable scaffolds: Clinical translations derived from a proof-of-concept

Background: Three-dimensional design simulations of coronary metallic stents utilizing mathematical and computational algorithms have emerged as important tools for understanding biomechanical stent properties, predicting the interaction of the implanted platform with the adjacent tissue, and informing stent design enhancements. Herein, we demonstrate the hemodynamic implications following virtual implantation of bioresorbable scaffolds using finite element methods and advanced computational fluid dynamics (CFD) simulations to visualize the device-flow interaction immediately after implantation and following scaffold resorption over time. Methods and Results: CFD simulations with time averaged wall shear stress (WSS) quantification following virtual bioresorbable scaffold deployment in idealized straight and curved geometries were performed. WSS was calculated at the inflow, endoluminal surface (top surface of the strut), and outflow of each strut surface post-procedure (stage I) and at a time point when 33% of scaffold resorption has occurred (stage II). The average WSS at stage I over the inflow and outflow surfaces was 3.2 and 3.1 dynes/cm² respectively and 87.5 dynes/cm² over endoluminal strut surface in the straight vessel. From stage I to stage II, WSS increased by 100% and 142% over the inflow and outflow surfaces, respectively, and decreased by 27% over the endoluminal strut surface. In a curved vessel, WSS change became more evident in the inner curvature with an increase of 63% over the inflow and 66% over the outflow strut surfaces. Similar analysis at the proximal and distal edges demonstrated a large increase of 486% at the lateral outflow surface of the proximal scaffold edge. Conclusions: The implementation of CFD simulations over virtually deployed bioresorbable scaffolds demonstrates the transient nature of device/flow interactions as the bioresorption process progresses over time. Such hemodynamic device modeling is expected to guide future bioresorbable scaffold design.

Bioresorbable scaffolds for percutaneous coronary interventions

Innovations in drug-eluting stents (DES) have substantially reduced rates of in-segment restenosis and early stent thrombosis, improving clinical outcomes following percutaneous coronary interventions (PCI). However a fixed metallic implant in a vessel wall with restored patency and residual disease remains a precipitating factor for sustained local inflammation, in-stent neo-atherosclerosis and impaired vasomotor function increasing the risk for late complications attributed to late or very late stent thrombosis and late target lesion revascularization (TLR) (late catch-up).

The quest for optimal coronary stenting continues by further innovations in stent design and by using biocompatible materials other than cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding, local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics have been recently developed. These devices have been utilized in selected clinical applications so far providing preliminary evidence of safety showing comparable performance with current generation drug-eluting stents (DES).

Herein we provide a comprehensive overview of the current status of these technologies, we elaborate on the potential benefits of transient coronary scaffolds over permanent stents in the context of vascular reparation therapy, and we further focus on the evolving challenges these devices have to overcome to compete with current generation DES. Condensed Abstract:: The quest for optimizing percutaneous coronary interventions continues by iterative innovations in device materials beyond cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding; local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics were recently developed. These devices have been utilized in selected clinical applications providing preliminary evidence of safety showing comparable intermediate term clinical outcomes with current generation drug-eluting stents.

Plasma soluble urokinase-type plasminogen activator receptor level is independently associated with coronary microvascular function in patients with non-obstructive coronary artery disease

BACKGROUND

Soluble urokinase-type plasminogen activator receptor (suPAR) is a novel biomarker released from leukocytes and endothelial cells that has been associated with atherosclerotic cardiovascular disease. We hypothesized that plasma suPAR level is an independent predictor of coronary microvascular function.

METHODS

Coronary blood flow velocity and plasma suPAR levels were evaluated in patients with non-obstructive coronary artery disease. Coronary flow reserve (CFR) was calculated as the ratio of hyperemic to basal average peak blood flow velocity and coronary microvascular dysfunction was defined as CFR ≤ 2.0 in the setting of a fractional flow reserve value of ≥0.75. Plasma suPAR levels were measured using ELISA technique. The association between suPAR and CFR was investigated using univariate and multivariate regression analyses.

RESULTS

In 66 patients, 47% were men, 26% had diabetes, 68% had hypertension and 76% had dyslipidemia. Mean age was 55 ± 12 years and median suPAR level 2.82 (2.08-3.40) ng/mL. Plasma suPAR levels correlated with age (r = 0.31, p = 0.01), body mass index (r = 0.25, p = 0.04) and high-sensitivity C-reactive protein (hs-CRP) (r = 0.33, p = 0.009). While median suPAR level was not significantly different in patients with different cardiovascular risk factors, patients on statin therapy had significantly higher suPAR level (p = 0.03). SuPAR correlated negatively with CFR and, after multivariate adjustment for established cardiovascular risk factors, medications profiles and hs-CRP, suPAR remained an independent predictor of CFR (B = -0.30, p = 0.04), indicating an independent association between suPAR level and coronary microvascular function.

CONCLUSIONS

In this cross-sectional study, plasma suPAR level was an independent predictor of coronary microvascular function. Larger prospective clinical trials are warranted to investigate the prognostic value of this novel biomarker and the role of immune dysregulation in coronary microvascular disease.

Novel drug-eluting stents for coronary revascularization

Over the past decades, there has been significant evolution in coronary stents used in percutaneous coronary intervention. The current novel drug-eluting stents available in the United States represent significant advancements compared to angioplasty, bare-metal stents, and the first generation of drug-eluting stents (DES). The Xience everolimus-eluting stents, Promus everolimus-eluting stents, and Resolute zotarolimus-eluting stents currently demonstrate the optimal balance of safety and efficacy. Endeavor zotarolimus-eluting stents have shorter drug-elution courses, and recent evidence suggests that 3 months of dual antiplatelet therapy appears safe, making Endeavor preferred when early discontinuation of dual antiplatelet therapy is warranted. Despite these advances in stent design, the permanent polymer and metallic stent remain in the vessel wall and may precipitate sustained inflammation, persistent vasomotor dysfunction, and in-stent neo-atherosclerosis. Bioresorbable platforms with biodegradable polymers have been developed to overcome the aforementioned limitations, and the outcomes of ongoing clinical trials are eagerly anticipated to determine if these novel stents will further improve clinical outcomes.

Intracoronary optical coherence tomography and histology of overlapping everolimus-eluting bioresorbable vascular scaffolds in a porcine coronary artery model: the potential implications for clinical practice

OBJECTIVES

This study sought to assess the vascular response of overlapping Absorb stents compared with overlapping newer-generation everolimus-eluting metallic platform stents (Xience V [XV]) in a porcine coronary artery model.

BACKGROUND

The everolimus-eluting bioresorbable vascular scaffold (Absorb) is a novel approach to treating coronary lesions. A persistent inflammatory response, fibrin deposition, and delayed endothelialization have been reported with overlapping first-generation drug-eluting stents.

METHODS

Forty-one overlapping Absorb and overlapping Xience V (XV) devices (3.0 × 12 mm) were implanted in the main coronary arteries of 17 nonatherosclerotic pigs with 10% overstretch. Implanted coronary arteries were evaluated by optical coherence tomography (OCT) at 28 days (Absorb n = 11, XV n = 7) and 90 days (Absorb n = 11, XV n = 8), with immediate histological evaluation following euthanasia at the same time points. One animal from each time point was evaluated with scanning electron microscopy alone. A total of 1,407 cross sections were analyzed by OCT and 148 cross sections analyzed histologically.

RESULTS

At 28 days in the overlap, OCT analyses indicated 80.1% of Absorb struts and 99.4% of XV struts to be covered (p < 0.0001), corresponding to histological observations of struts with cellular coverage of 75.4% and 99.6%, respectively (p < 0.001). Uncovered struts were almost exclusively related to the presence of "stacked" Absorb struts, that is, with a direct overlay configuration. At 90 days, overlapping Absorb and overlapping XV struts demonstrated >99% strut coverage by OCT and histology, with no evidence of a significant inflammatory process, and comparable % volume obstructions.

CONCLUSIONS

In porcine coronary arteries implanted with overlapping Absorb or overlapping XV struts, strut coverage is delayed at 28 days in overlapping Absorb, dependent on the overlay configuration of the thicker Absorb struts. At 90 days, both overlapping Absorb and overlapping XV have comparable strut coverage. The implications of increased strut thickness may have important clinical and design considerations for bioresorbable platforms.

Assessment of plaque evolution in coronary bifurcations located beyond everolimus eluting scaffolds: serial intravascular ultrasound virtual histology study

Purpose

To evaluate the atherosclerotic evolution in coronary bifurcations located proximally and distally to a bioresorbable scaffold.

Methods

Thirty bifurcations located >5 mm beyond the scaffolded segment, being investigated with serial intravascular ultrasound virtual histology (IVUS-VH) examinations, at baseline and 2-years, in patients enrolled in the ABSORB cohort B1 study were included in this analysis. In each bifurcation, the frames portraying the proximal rim, in-bifurcation, and distal rim of the ostium of the side branch were analyzed. The geometric parameters and plaque types were evaluated at baseline and 2-years follow-up.

Results

There were no significant differences in the geometrical parameters such as lumen, vessel and plaque areas as well as in the composition of the atheroma between baseline and 2-years follow-up.

When we separately examined the bifurcations located proximally and distally to the scaffolded segment, no changes were found at the distal bifurcations, while at the proximal bifurcations there was a statistical significant decrease in the plaque burden (36.67 ± 13.33% at baseline vs. 35.06 ± 13.20% at 2 years follow-up, p = 0.04).

Ten necrotic core rich plaques were found at baseline, of which 2 regressed to either fibrotic plaque or to intimal thickening at 2 years follow-up. The other 8 did not change. Disease progression was noted in 3 plaques (1 adaptive intimal thickening, 1 fibrotic and 1 fibrocalcific plaque) that evolved to necrotic rich plaques.

Conclusions

Plaque regression was noted at the bifurcations located proximally to the bioresorbable scaffold but not at these located distally. Additional studies are required to confirm this finding and examine further the effect of drug elution on atherosclerotic evolution.

Progress in treatment by percutaneous coronary intervention: the stent of the future

First generation drug-eluting stents have considerably reduced in-stent restenosis and broadened the applications of percutaneous coronary interventions for the treatment of coronary artery disease. The polymer is an integral part of drug-eluting stents in that, it controls the release of an antiproliferative drug. The main safety concern of first generation drug-eluting stents with permanent polymers--stent thrombosis--has been caused by local hypersensitivity, delayed vessel healing, and endothelial dysfunction. This has prompted the development of newer generation drug-eluting stents with biodegradable polymers or even polymer-free drug-eluting stents. Recent clinical trials have shown the safety and efficacy of drug-eluting stents with biodegradable polymer, with proven reductions in very late stent thrombosis as compared to first generation drug-eluting stents. However, the concept of using a permanent metallic prosthesis implies major drawbacks, such as the presence of a foreign material within the native coronary artery that causes vascular inflammation and neoatherosclerosis, and also impedes the restoration of the vasomotor function of the stented segment. Bioresorbable scaffolds have been introduced to overcome these limitations, since they provide temporary scaffolding and then disappear, liberating the treated vessel from its cage. This update article presents the current status of these new technologies and highlights their future perspectives in interventional cardiology.

Clinical and intravascular imaging outcomes at 1 and 2 years after implantation of absorb everolimus eluting bioresorbable vascular scaffolds in small vessels. Late lumen enlargement: does bioresorption matter with small vessel size? Insight from the ABSORB cohort B trial

BACKGROUND

The long-term results after second generation everolimus eluting bioresorbable vascular scaffold (Absorb BVS) placement in small vessels are unknown. Therefore, we investigated the impact of vessel size on long-term outcomes, after Absorb BVS implantation.

METHODS

In ABSORB Cohort B Trial, out of the total study population (101 patients), 45 patients were assigned to undergo 6-month and 2-year angiographic follow-up (Cohort B1) and 56 patients to have angiographic follow-up at 1-year (Cohort B2). The pre-reference vessel diameter (RVD) was <2.5 mm (small-vessel group) in 41 patients (41 lesions) and ≥2.5 mm (large-vessel group) in 60 patients (61 lesions). Outcomes were compared according to pre-RVD.

RESULTS

At 2-year angiographic follow-up no differences in late lumen loss (0.29±0.16 mm vs 0.25±0.22 mm, p=0.4391), and in-segment binary restenosis (5.3% vs 5.3% p=1.0000) were demonstrated between groups. In the small-vessel group, intravascular ultrasound analysis showed a significant increase in vessel area (12.25±3.47 mm(2) vs 13.09±3.38 mm(2) p=0.0015), scaffold area (5.76±0.96 mm(2) vs 6.41±1.30 mm(2) p=0.0008) and lumen area (5.71±0.98 mm(2) vs 6.20±1.27 mm(2) p=0.0155) between 6-months and 2-year follow-up. No differences in plaque composition were reported between groups at either time point. At 2-year clinical follow-up, no differences in ischaemia-driven major adverse cardiac events (7.3% vs 10.2%, p=0.7335), myocardial infarction (4.9% vs 1.7%, p=0.5662) or ischaemia-driven target lesion revascularisation (2.4% vs 8.5%, p=0.3962) were reported between small and large vessels. No deaths or scaffold thrombosis were observed.

CONCLUSIONS

Similar clinical and angiographic outcomes at 2-year follow-up were reported in small and large vessel groups. A significant late lumen enlargement and positive vessel remodelling were observed in small vessels.

Vascular compliance changes of the coronary vessel wall after bioresorbable vascular scaffold implantation in the treated and adjacent segments

BACKGROUND

Implantation of a metallic prosthesis creates local stiffness with a subsequent mismatch in the compliance of the vessel wall, disturbances in flow and heterogeneous distribution of wall shear stress. Polymeric bioresorbable ABSORB scaffolds have less stiffness than metallic platform stents. We sought to analyze the mismatch in vascular compliance after ABSORB implantation and its long-term resolution with bioresorption.

METHODS AND RESULTS

A total of 83 patients from the ABSORB trials underwent palpography investigations (30 and 53 patients from ABSORB Cohorts A and B, respectively) to measure the compliance of the scaffolded and adjacent segments at various time points (from pre-implantation up to 24 months). The mean of the maximum strain values was calculated per segment by utilizing the Rotterdam Classification (ROC) score and expressed as ROC/mm. Scaffold implantation lead to a significant decrease in vascular compliance (median [IQR]) at the scaffolded segment (from 0.37 [0.24-0.45] to 0.14 [0.09-0.23], P<0.001) with mismatch in compliance in a paired analysis between the scaffolded and adjacent segments (proximal: 0.23 [0.12-0.34], scaffold: 0.12 [0.07-0.19], distal: 0.15 [0.05-0.26], P=0.042). This reported compliance mismatch disappears at short- and mid-term follow-up.

CONCLUSIONS

The ABSORB scaffold decreases vascular compliance at the site of scaffold implantation. A compliance mismatch is evident immediately post-implantation and in contrast to metallic stents disappears in the mid-term, likely leading to a normalization of the rheological behavior of the scaffolded segment.