Robin P. Kraak

Bioresorbable Scaffolds versus Metallic Stents in Routine PCI

BACKGROUND Bioresorbable vascular scaffolds were developed to overcome the shortcomings of drug‐eluting stents in percutaneous coronary intervention (PCI). We performed an investigator‐initiated, randomized trial to compare an everolimus‐eluting bioresorbable scaffold with an everolimus‐eluting metallic stent in the context of routine clinical practice. METHODS We randomly assigned 1845 patients undergoing PCI to receive either a bioresorbable vascular scaffold (924 patients) or a metallic stent (921 patients). The primary end point was target‐vessel failure (a composite of cardiac death, target‐vessel myocardial infarction, or target‐vessel revascularization). The data and safety monitoring board recommended early reporting of the study results because of safety concerns. This report provides descriptive information on end‐point events. RESULTS The median follow‐up was 707 days. Target‐vessel failure occurred in 105 patients in the scaffold group and in 94 patients in the stent group (2‐year cumulative event rates, 11.7% and 10.7%, respectively; hazard ratio, 1.12; 95% confidence interval [CI], 0.85 to 1.48; P=0.43); event rates were based on Kaplan–Meier estimates in time‐to‐event analyses. Cardiac death occurred in 18 patients in the scaffold group and in 23 patients in the stent group (2‐year cumulative event rates, 2.0% and 2.7%, respectively), target‐vessel myocardial infarction occurred in 48 patients in the scaffold group and in 30 patients in the stent group (2‐year cumulative event rates, 5.5% and 3.2%), and target‐vessel revascularization occurred in 76 patients in the scaffold group and in 65 patients in the stent group (2‐year cumulative event rates, 8.7% and 7.5%). Definite or probable device thrombosis occurred in 31 patients in the scaffold group as compared with 8 patients in the stent group (2‐year cumulative event rates, 3.5% vs. 0.9%; hazard ratio, 3.87; 95% CI, 1.78 to 8.42; P<0.001). CONCLUSIONS In this preliminary report of a trial involving patients undergoing PCI, there was no significant difference in the rate of target‐vessel failure between the patients who received a bioresorbable scaffold and the patients who received a metallic stent. The bioresorbable scaffold was associated with a higher incidence of device thrombosis than the metallic stent through 2 years of follow‐up. (Funded by Abbott Vascular; AIDA ClinicalTrials.gov number, NCT01858077.)

Initial experience and clinical evaluation of the Absorb bioresorbable vascular scaffold (BVS) in real-world practice: the AMC Single Centre Real World PCI Registry.

AIMS To report procedural and midterm clinical outcomes after the use of the second-generation Absorb everolimus-eluting bioresorbable vascular scaffold (Absorb BVS) in a real-world percutaneous coronary intervention (PCI) registry. METHODS AND RESULTS All patients assigned to treatment with the Absorb BVS in the Academic Medical Center, Amsterdam, between August 2012 and August 2013 were included in a prospective registry. A total of 135 patients were included in the study, including 53 (39%) acute coronary syndrome (ACS) patients (13% ST-segment elevation myocardial infarction [STEMI]). In total 159 lesions were treated, including 102 (62%) with a type B2 or C classification. Pre- and post-procedural quantitative coronary angiography (QCA) analyses showed an acute gain of 1.37±0.53 mm. An angiographic success rate was achieved in 152 (96%) of the lesions. Six-month follow-up was available in 97% of the patients. Six-month cumulative target vessel failure (composite of all-cause mortality, any myocardial infarction [MI] and target vessel revascularisation [TVR]) rate was 8.5%, including a 3.0% MI, 3.0% definite scaffold thrombosis, 6.3% target lesion revascularisation, and an 8.5% TVR rate. CONCLUSIONS The use of the Absorb BVS in a cohort reflecting daily clinical practice is feasible and associated with good procedural safety and angiographic success rate. In addition, six-month follow-up is associated with acceptable clinical outcomes.

Treatment of coronary bifurcation lesions with the Absorb bioresorbable vascular scaffold in combination with the Tryton dedicated coronary bifurcation stent: evaluation using two- and three-dimensional optical coherence tomography.

AIMS The Tryton bifurcation stent has been developed to improve clinical outcomes after treatment of bifurcation lesions. Limited data are available on the use of the Absorb bioresorbable vascular scaffold (BVS) in bifurcation lesions with side branches >2 mm. We present here the acute procedural results and midterm clinical follow-up of the first-in-man combined use of the Tryton stent and the Absorb scaffold for the treatment of complex bifurcation lesions. METHODS AND RESULTS Ten patients treated with the Tryton stent in combination with Absorb BVS were included in the current report. Offline two- and three-dimensional optical coherence tomography (OCT) analyses were performed to gain more insights into this novel approach. Procedural success was 91%, whereas angiographic success was achieved in 82%. Two TLRs occurred (TLR rate 20%), whereas no deaths, myocardial infarctions or stent thromboses were observed up to six months of follow-up. CONCLUSIONS We present a new treatment strategy in complex bifurcation lesions using the Tryton stent in combination with the Absorb BVS. This approach potentially offers an opportunity to treat complex bifurcation lesions with the Absorb BVS. Furthermore, three-dimensional OCT reconstructions give valuable insights into PCI of complex bifurcation lesions.

Two-year clinical outcomes of Absorb bioresorbable vascular scaffold implantation in complex coronary artery disease patients stratified by SYNTAX score and ABSORB II study enrolment criteria

AIMS This study presents the two-year clinical outcomes of the Amsterdam ABSORB registry stratified by lesion and patient characteristics complexity (SYNTAX score and ABSORB II study enrolment criteria). METHODS AND RESULTS Patients treated with BVS were included in this prospective registry and stratified according to the ABSORB II trial inclusion and exclusion criteria and the SYNTAX score. The registry comprises 135 patients (59±11 years, 73% male, 18% diabetic) with 159 lesions. Median follow-up duration was 774 days (742-829). Median SYNTAX score was 11.5 (Q1-Q3: 6-17.5). Two-year event rates were cardiac death 0.7%, MI 5.3%, TVR 13.6%, TLR 11.4%, definite ST 3.0% and TVF 14.4%, respectively. Stratified analyses showed a significantly higher revascularisation rate in patients not meeting ABSORB II criteria (TVR: 2.3% vs. 19.2%, p=0.010, and TLR: 2.3% vs. 15.8%, p=0.025) and patients with SYNTAX score ≥11.5 (TVR: 4.8% vs. 21.8%, p=0.006, and TLR: 3.2% vs. 17.4%, p=0.007). CONCLUSIONS The use of Absorb BVS in patients meeting the ABSORB II trial inclusion criteria or those with low SYNTAX scores is associated with acceptable clinical outcomes at two-year follow-up. Patients with more complex characteristics have significantly higher revascularisation rates.

Coronary Artery Vessel Healing Pattern, Short and Long Term, After Implantation of the Everolimus‐Eluting Bioresorbable Vascular Scaffold

Background Although the Absorb bioresorbable vascular scaffold is increasingly used in daily clinical practice for the treatment of coronary artery disease, the exact vascular healing pattern and the resorption process in humans is unknown because histological data are derived only from animal studies. Methods and Results We have obtained 4 autopsies (5 scaffolds) since August 2013. Duration of bioresorbable vascular scaffold implantation ranged from 3 to 501 days. All autopsies and histological assessments were performed by dedicated cardiovascular pathologists. At 1 week after bioresorbable vascular scaffold implantation, struts were covered with a fine layer of fibrin and platelets. At 113 days, the scaffold struts were fully covered with smooth muscle cells. Hyaline eosinophilic and proteoglycan material infiltrating the scaffold struts was observed at 501 days after implantation. At all time points, we observed the presence of multinuclear foreign body giant cells adjacent to the scaffold struts. Conclusions Resorption and healing processes after bioresorbable vascular scaffold implantation in human patients mirror those observed in porcine models. The presence of multinucleated foreign body giant cells at both short‐ and long‐term follow‐up needs further investigation and may be related to a low‐grade absorptive inflammatory response to the polymer.

Side branch healing patterns of the Tryton dedicated bifurcation stent: a 1-year optical coherence tomography follow-up study

The bare-metal Tryton Side Branch (SB) Stent™ (Tryton Medical, Durham, NC, USA) is used with a drug-eluting stent (DES) in the main branch (MB) to treat bifurcation lesions. It is argued that a drug-eluting Tryton-version is needed to improve clinical outcomes, although previous registries have shown good clinical results. More insights in neo-intimal hyperplasia (NIH) growth patterns of the Tryton treatment strategy are needed to decide if and where to drug-coat the stent. Ten patients returned for follow-up angiography (mean follow-up time 393 ± 103 days) and optical coherence tomography (OCT) pullbacks from the MB were obtained in all patients and from the SB in six patients. A per-strut analysis showed an uncovered strut rate of 0.7 % and an incompletely-apposed strut rate of 0.8 %. Most incompletely-apposed struts were found at the bifurcation region, in the luminal half facing towards the SB. Mean NIH thickness in the proximal MB, distal MB and SB were 0.14 ± 0.11, 0.19 ± 0.11, and 0.34 ± 0.19 mm, respectively, with a variety of growth patterns observed in the SB. We found good vascular healing of the DES in the MB, while healing was less favourably in the SB part. Furthermore, we observed a variety of NIH growth patterns in this SB part and more studies are needed to investigate the relation between growth patterns and clinical outcomes.

Bioresorbable scaffolds for the treatment of coronary artery disease: current status and future perspective

Bioresorbable scaffolds represent a novel approach in the treatment of coronary artery disease which allows for vessel wall support without leaving a permanent foreign body in the coronary artery. This technology has the potential to reduce some of the shortcomings of current standard treatment with metallic drug-eluting stents, such as late in-stent restenosis, impaired vasomotion of the stented segment and hindrance of surgical revascularizations. Currently, several bioresorbable scaffolds are available and undergoing clinical or preclinical evaluation. This review will present the current status of development of bioresorbable scaffolds, describe the degradation/resorption process of each device and the clinical data available to date.

First report on long-term clinical results after treatment of coronary bifurcation lesions with the Tryton dedicated bifurcation stent

To improve clinical outcomes after percutaneous coronary interventions of coronary bifurcation lesions, the Tryton Side Branch Stent™ (Tryton Medical, Durham) was developed. Registry studies evaluating the Tryton stent has shown promising clinical results and the stent is currently compared with the provisional single stent strategy in a randomized trial. However, clinical results beyond one year are lacking, and therefore, we investigated the one‐ and two‐year outcomes after Tryton stent placement in a single‐center registry study.

Bioresorbable drug-eluting scaffolds for treatment of vascular disease

ABSTRACT Introduction: Theoretical advantages of fully bioresorbable scaffold (BRS) stem from transient vessel support without rigid caging. Therefore, it could reduce long-term adverse events associated with the presence of foreign materials. Areas covered: This article will provide an overview of: drug-eluting BRS for various applications in the treatment of vascular disease; The mechanisms of active agent release from such scaffolds; currently available drug-eluting BRS and their future applications are also discussed. Expert opinion: The current BRS have been developed in order to achieve optimal vascular patency while providing long-term safety. The clinical efficacy and safety of BRS in coronary treatment have been reported as equal to that of the current metallic drug eluting stents in simple lesions. The application of BRS can potentially be expanded to other vascular beds. The research in bioengineering for the appropriate materials should not only focus on biocompatibility but also should be tailored according to the sites of implantation, which may require different strength and supporting period. The ultimate goal in this field is to develop a biocompatible device that provides equivalent and complementary therapy to other devices, and is able to disappear when the mechanical support and drug delivery are no longer required.

The IMPACT Study (Influence of Sensor-Equipped Microcatheters on Coronary Hemodynamics and the Accuracy of Physiological Indices of Functional Stenosis Severity)

Background—The Navvus pressure sensor–equipped microcatheter allows to measure functional stenosis severity over a work-horse guidewire and is used as a more feasible alternative to regular sensor-equipped wires. However, Navvus is larger in diameter than contemporary sensor-equipped guidewires and may, thereby, influence functional measurements. The present study evaluates the hemodynamic influence of the Navvus microcatheter. Methods and Results—In patients with intermediate coronary stenosis, coronary pressure and flow velocity were measured using a dual sensor–equipped guidewire before and after introduction of Navvus. Patients were randomized to microcatheter-first or guidewire-first measurement. The primary end point was the difference in hyperemic stenosis resistance index between measurements before and after introduction of Navvus. Measurements were completed in 28 patients (28 stenoses). Mean hyperemic stenosis resistance was 0.37±0.19 Hg/cm/s for wire-only assessment and 0.48±0.26 Hg/cm/s after Navvus introduction (P<0.001). Bland–Altman analysis documented a mean bias of +0.11 Hg/cm/s (limits of agreement: −0.13 to 0.36), proportional to mean hyperemic stenosis resistance (Spearman &rgr; =0.61; P=0.001). Passing–Bablok analysis revealed absence of a constant difference but significant proportional difference between the methods. Mean fractional flow reserve was 0.86±0.06 for wire-only assessment and 0.82±0.07 after Navvus introduction (P<0.001). Bland–Altman analysis documented a mean bias of −0.033 (limits of agreement: −0.09 to 0.03), proportional to mean fractional flow reserve (Spearman &rgr; =0.40; P=0.036). Passing–Bablok analysis revealed significant constant and proportional differences between methods. Similar results were documented for resting indices of stenosis severity. Conclusions—Introduction of the Navvus microcatheter leads to clinically relevant stenosis severity overestimation in intermediate stenosis.