Comparison of acute thrombogenicity and albumin adsorption in three different durable polymer coronary drug-eluting stents

Stent thrombosis in the setting of ST-segment elevation acute myocardial infarction in the contemporary practice: results from the TOTAL randomized trial

The aim was to know the risk and predictive factors of stent thrombosis (ST) in patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) in the contemporary practice. The TOTAL [ThrOmbecTomy with percutaneous coronary intervention (PCI) versus PCI ALone] randomized trial, being the largest trial performed in the setting of STEMI with a general application of the recent recommendations, represents a unique opportunity to know the current real-world incidence of ST as well as its associated factors. A total of 10 064 patients that received ≥1 coronary stent in the TOTAL trial comprise the study population. The risk, predictive factors, and clinical implications of ST was studied. During 1-year follow-up, 155 patients (1.54%) suffered definitive or probable ST (59 acute, 67 subacute, and 29 late). Previous infarction, the number of stents, the previous use of clopidogrel, and the use of diuretics at discharge were independent predictors for ST, whereas the use of upfront glycoprotein IIb/IIIa inhibitors, radial access, and treatment with statins at discharge were independent protective factors. The number of stents, stent diameter, upfront treatment with IIb/IIIa inhibitors, previous treatment with clopidogrel, and treatment with statins at discharge were independently associated with the risk of early ST. Only previous infarction was associated with the risk of late ST. In the contemporary practice, ST still constitutes a frequent complication of primary PCI for STEMI, occurring in 1.5% of patients. Independent predictors are different depending on the time of ST.

Biodegradable Polymer Versus Polymer-Free Ultrathin Sirolimus-Eluting Stents: Analysis of the Stent Arm Registry From the HOST-IDEA Randomized Trial

BACKGROUND

The efficacy and safety of each third-generation drug-eluting stent with ultrathin struts and advanced polymer technology remain unclear. We investigated the clinical outcomes of percutaneous coronary intervention using the Coroflex ISAR polymer-free sirolimus-eluting stent (SES) or Orsiro biodegradable polymer SES.

METHODS

The HOST-IDEA trial (Harmonizing Optimal Strategy for Treatment of Coronary Artery Stenosis-Coronary Intervention With Next-Generation Drug-Eluting Stent Platforms and Abbreviated Dual Antiplatelet Therapy), initially designed with a 2×2 factorial approach, sought to randomize patients undergoing percutaneous coronary intervention based on dual antiplatelet therapy duration (3 versus 12 months) and stent type (Coroflex ISAR versus Orsiro). Despite randomizing 2013 patients for dual antiplatelet therapy duration, the stent arm transitioned to a registry format during the trial. Among these, 328 individuals (16.3%) were randomized for Coroflex ISAR or Orsiro SES, while 1685 (83.7%) underwent percutaneous coronary intervention without stent-type randomization. In this study, the Coroflex ISAR (n=559) and Orsiro groups (n=1449) were matched using a propensity score. The prespecified primary end point was target lesion failure, a composite of cardiac death, target vessel myocardial infarction, and clinically driven target lesion revascularization at 12 months.

RESULTS

The baseline patient and procedural characteristics were well balanced between the Coroflex ISAR and Orsiro groups after propensity score matching (n=559, each group). The Coroflex ISAR group was significantly associated with a higher rate of target lesion failure, mainly driven by clinically driven target lesion revascularization, compared with the Orsiro group (3.4% versus 1.1%; hazard ratio, 3.21 [95% CI, 1.28-8.05]; P=0.01). A higher risk of target lesion failure in the Coroflex ISAR group was consistently observed across various subgroups. The rates of any bleeding (hazard ratio, 0.85 [95% CI, 0.51-1.40]; P=0.52) and major bleeding (hazard ratio, 1.58 [95% CI, 0.61-4.08]; P=0.34) were comparable between the 2 groups.

CONCLUSIONS

In this propensity score-matched analysis of the stent arm registry from the HOST-IDEA trial, the Orsiro SES was associated with significantly better outcomes in terms of 1-year target lesion failure, mainly driven by clinically driven target lesion revascularization, than the Coroflex ISAR SES.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02601157.

Challenges and advances in device-related thrombus in left atrial appendage occlusion

Oral anticoagulation therapy (OAC) is a mainstay for mitigating stroke and other embolic events in patients with atrial fibrillation (AF). Despite the demonstrated efficacy of OAC in reducing events, many patients are unable to tolerate OAC due to bleeding risks. Left atrial appendage occlusion (LAAO) devices were developed as implantable technologies to moderate stroke risk in patients with intolerance to OAC. Despite clinical data supporting near-comparable protection against thromboembolic events with OAC, device-related thrombus formation has emerged as a critical complication following LAAO that remains a potential limitation to the safety and efficacy of LAAO. Improved biocompatibility of LAAO devices with fluoropolymers, a well-established stent-coating technology used to reduce thrombus formation and promote endothelialization, may optimize outcomes after LAAO.

Comparison of thrombogenicity in different types of drug-eluting stents during transition from DAPT to SAPT

BACKGROUND

During the transition from dual antiplatelet therapy (DAPT) to single antiplatelet therapy (SAPT), previous studies have raised concerns about a rebound effect. We compared platelet and inflammatory cell adhesion on different types of stents in the setting of clopidogrel presence and withdrawal.

METHODS

In Experiment 1, three pigs were administered with DAPT, that is, clopidogrel and acetylsalicylic acid (ASA), for 7 days. Each animal underwent an extracorporeal carotid arteriovenous shunt model implanted with fluoropolymer-coated everolimus-eluting stent (FP-EES), biodegradable-polymer sirolimus-eluting stent (BP-SES), and biodegradable-polymer everolimus-eluting stents (BP-EES). In Experiment 2, two pigs were administered DAPT, clopidogrel was then withdrawn at day 7, and SAPT with ASA was continued for next 21 days. Then flow-loop experiments with the drawn blood from each time point were performed for FP-EES, BioLinx-polymer zotarolimus-eluting stents (BL-ZES), and BP-EES. The rebound effect was defined as the statistical increase of inflammation and platelet adhesion assessed with immunohistochemistry on the stent-strut level basis from baseline to day-14 or 28.

RESULTS

Both experiments showed platelet adhesion value was highest in BP-EES, while the least in FP-EES during DAPT therapy. There was no increase in platelet or inflammatory cell adhesion above baseline values (i.e., no therapy) due to the cessation of clopidogrel on the stent-strut level. Monocyte adhesion was the least for FP-EES with the same trend observed for neutrophil adhesion.

CONCLUSIONS

No evidence of rebound effect was seen after the transition from DAPT to SAPT. FP-EES demonstrated the most favorable antithrombotic and anti-inflammatory profile regardless of the different experimental designs.

Durable-polymer versus biodegradable-polymer drug-eluting stents in acute coronary syndromes: three-year outcomes of the HOST REDUCE POLYTECH RCT Trial

BACKGROUND

Long-term follow-up is essential to evaluate the impact of polymer degradation in drug-eluting stents (DES).

AIMS

We aimed to compare durable-polymer DES (DP-DES) and biodegradable-polymer DES (BP-DES) during a 3-year follow-up to evaluate the entire period of polymer resolution (before, during, and after degradation).

METHODS

The HOST REDUCE POLYTECH RCT Trial was a randomised clinical trial enrolling patients with acute coronary syndrome (ACS) and comparing the efficacy and safety of DP-DES and BP-DES. The primary outcome was a patient-oriented composite outcome (POCO), and the key secondary outcome was a device-oriented composite outcome (DOCO).

RESULTS

A total of 3,413 ACS patients were randomised to either the DP-DES (1,713 patients) or BP-DES (1,700 patients) group. During the 3-year follow-up, the risk of the POCO was similar between the DP-DES and BP-DES groups (14.8% vs 15.4%, hazard ratio [HR] 0.96, 95% confidence interval [CI]: 0.80-1.14; p=0.613). However, the risk of the DOCO was lower in the DP-DES group (6.0% vs 8.0%, HR 0.73, 95% CI: 0.57-0.95; p=0.020). In a landmark analysis, the lower risk of the DOCO for the DP-DES group was evident during the transition from the early to the late period after percutaneous coronary intervention (PCI) (from 8 to 16 months post-PCI; 1.8% vs 3.3%, HR 0.54, 95% CI: 0.34-0.84; p=0.007), which was mainly driven by a risk reduction of target lesion revascularisation.

CONCLUSIONS

In ACS patients, DP-DES showed similar results to BP-DES regarding the POCO up to 3 years. For the DOCO, DP-DES were superior to BP-DES; this was due to the higher event rate during the period of polymer degradation.

Enhanced Thromboresistance and Endothelialization of a Novel Fluoropolymer-Coated Left Atrial Appendage Closure Device

BACKGROUND

Device-related thrombus (DRT) after left atrial appendage closure (LAAC) procedures is a rare but potentially serious event. Thrombogenicity and delayed endothelialization play a role in the development of DRT. Fluorinated polymers are known to have thromboresistant properties that may favorably modulate the healing response to an LAAC device.

OBJECTIVES

The goal of this study was to compare the thrombogenicity and endothelial coverage (EC) after LAAC between the conventional uncoated WATCHMAN FLX (WM) and a novel fluoropolymer-coated WATCHMAN FLX (FP-WM).

METHODS

Canines were randomized for implantation with WM or FP-WM devices and given no postimplant antithrombotic/antiplatelet agents. The presence of DRT was monitored by using transesophageal echocardiography and verified histologically. The biochemical mechanisms associated with coating were assessed by using flow loop experiments to quantify albumin adsorption, platelet adhesion, and porcine implants to quantify EC and the expression of markers of endothelial maturation (ie, vascular endothelial-cadherin/p120-catenin).

RESULTS

Canines implanted with FP-WM exhibited significantly less DRT at 45 days than those implanted with WM (0% vs 50%; P < 0.05). In vitro experiments showed significantly greater albumin adsorption (52.8 [IQR: 41.0-58.3] mm2 vs 20.6 [IQR: 17.2-26.6] mm2; P = 0.03) and significantly less platelet adhesion (44.7% [IQR: 27.2%-60.2%] vs 60.9% [IQR: 39.9%-70.1%]; P < 0.01) on FP-WM. Porcine implants showed significantly greater EC by scanning electron microscopy (87.7% [IQR: 83.4%-92.3%] vs 68.2% [IQR: 47.6%-72.8%]; P = 0.03), and higher vascular endothelial-cadherin/p120-catenin expression after 3 months on FP-WM compared with WM.

CONCLUSIONS

The FP-WM device showed significantly less thrombus and reduced inflammation in a challenging canine model. Mechanistic studies indicated that the fluoropolymer-coated device binds more albumin, leading to reduced platelet binding, less inflammation, and greater EC.

Restoring endothelial function: shedding light on cardiovascular stent development

Complete endothelialization is highly important for maintaining long-term patency and avoiding subsequent complications in implanting cardiovascular stents. It not only refers to endothelial cells (ECs) fully covering the inserted stents, but also includes the newly formed endothelium, which could exert physiological functions, such as anti-thrombosis and anti-stenosis. Clinical outcomes have indicated that endothelial dysfunction, especially the insufficiency of antithrombotic and barrier functions, is responsible for stent failure. Learning from vascular pathophysiology, endothelial dysfunction on stents is closely linked to the microenvironment of ECs. Evidence points to inflammatory responses, oxidative stress, altered hemodynamic shear stress, and impaired endothelial barrier affecting the normal growth of ECs, which are the four major causes of endothelial dysfunction. The related molecular mechanisms and efforts dedicated to improving the endothelial function are emphasized in this review. From the perspective of endothelial function, the design principles, advantages, and disadvantages behind current stents are introduced to enlighten the development of new-generation stents, aiming to offer new alternatives for restoring endothelial function.

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.

Comparison between biodegradable- and durable-polymer everolimus-eluting stents in hemodialysis patients with coronary artery disease

To investigate the clinical outcomes after biodegradable-polymer (BP) and durable-polymer (DP) everolimus-eluting stent (EES) implantation in hemodialysis (HD) patients with coronary artery disease. We enrolled 221 consecutive HD patients successfully treated with EES implantation for coronary lesions. Over the following 2 years, we assessed the incidence of target lesion revascularization (TLR) and major adverse cardiac event (MACE), defined as the composite endpoint of TLR, all-cause mortality, or myocardial infarction. We performed a propensity-score matching analysis and collected follow-up coronary angiography data. There were 91 patients in the BP-EES group and 130 in the DP-EES group. Male sex and diabetes rates were significantly lower in the BP-EES group than in the DP-EES group. A debulking device was less frequently used in the BP-EES group than in the DP-EES group (7.6% vs. 21.5%, p = 0.006). TLR occurred in 38 patients, while stent thrombosis was observed in 3 patients; 19 patients died. TLR and MACE rates at 2 years were comparable between the two groups (19.2% in the BP-EES group vs. 20.4% in the DP-EES group, p = 0.73 and 26.9% vs. 34.2%, p = 0.93, respectively). In the propensity-score-matched cohort, TLR and MACE rates were similar between the two groups (19.2% in the BP-EES group vs. 18.1% in the DP-EES group, p = 0.69, and 26.9% vs. 30.2%, p = 0.66, respectively). Restenosis rates at follow-up angiography were similar between the two groups (p = 0.79). In hemodialysis patients, BP-EES and DP-EES showed similar 2-year clinical outcomes.

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.

Vascular Wall Reactions to Coronary Stents-Clinical Implications for Stent Failure

Coronary stents belong to the most commonly implanted devices worldwide. A number of different types of stent exist, with very different mechanical and biochemical characteristics that influence their interactions with vascular tissues. Inappropriate inflammatory reactions are the major cause of the two major complications that follow implantation of stents in a percentage as high as 5-20%. It is therefore important to understand these reactions and how different they are among different generations of stents.