Effect of Transcatheter Aortic Valve Implantation vs Surgical Aortic Valve Replacement on All-Cause Mortality in Patients With Aortic Stenosis: A Randomized Clinical Trial.

Importance: Transcatheter aortic valve implantation (TAVI) is a less invasive alternative to surgical aortic valve replacement and is the treatment of choice for patients at high operative risk. The role of TAVI in patients at lower risk is unclear. Objective: To determine whether TAVI is noninferior to surgery in patients at moderately increased operative risk. Design, Setting, and Participants: In this randomized clinical trial conducted at 34 UK centers, 913 patients aged 70 years or older with severe, symptomatic aortic stenosis and moderately increased operative risk due to age or comorbidity were enrolled between April 2014 and April 2018 and followed up through April 2019. Interventions: TAVI using any valve with a CE mark (indicating conformity of the valve with all legal and safety requirements for sale throughout the European Economic Area) and any access route (n = 458) or surgical aortic valve replacement (surgery; n = 455). Main Outcomes and Measures: The primary outcome was all-cause mortality at 1 year. The primary hypothesis was that TAVI was noninferior to surgery, with a noninferiority margin of 5% for the upper limit of the 1-sided 97.5% CI for the absolute between-group difference in mortality. There were 36 secondary outcomes (30 reported herein), including duration of hospital stay, major bleeding events, vascular complications, conduction disturbance requiring pacemaker implantation, and aortic regurgitation. Results: Among 913 patients randomized (median age, 81 years [IQR, 78 to 84 years]; 424 [46%] were female; median Society of Thoracic Surgeons mortality risk score, 2.6% [IQR, 2.0% to 3.4%]), 912 (99.9%) completed follow-up and were included in the noninferiority analysis. At 1 year, there were 21 deaths (4.6%) in the TAVI group and 30 deaths (6.6%) in the surgery group, with an adjusted absolute risk difference of -2.0% (1-sided 97.5% CI, -∞ to 1.2%; P < .001 for noninferiority). Of 30 prespecified secondary outcomes reported herein, 24 showed no significant difference at 1 year. TAVI was associated with significantly shorter postprocedural hospitalization (median of 3 days [IQR, 2 to 5 days] vs 8 days [IQR, 6 to 13 days] in the surgery group). At 1 year, there were significantly fewer major bleeding events after TAVI compared with surgery (7.2% vs 20.2%, respectively; adjusted hazard ratio [HR], 0.33 [95% CI, 0.24 to 0.45]) but significantly more vascular complications (10.3% vs 2.4%; adjusted HR, 4.42 [95% CI, 2.54 to 7.71]), conduction disturbances requiring pacemaker implantation (14.2% vs 7.3%; adjusted HR, 2.05 [95% CI, 1.43 to 2.94]), and mild (38.3% vs 11.7%) or moderate (2.3% vs 0.6%) aortic regurgitation (adjusted odds ratio for mild, moderate, or severe [no instance of severe reported] aortic regurgitation combined vs none, 4.89 [95% CI, 3.08 to 7.75]). Conclusions and Relevance: Among patients aged 70 years or older with severe, symptomatic aortic stenosis and moderately increased operative risk, TAVI was noninferior to surgery with respect to all-cause mortality at 1 year. Trial Registration: isrctn.com Identifier: ISRCTN57819173.

Initial experience of a self-expanding transcatheter aortic valve with an outer pericardial wrap: The United Kingdom and Ireland Implanters' registry.

OBJECTIVES: The United Kingdom and Ireland Implanters' registry is a multicenter registry which reports on real-world experience with new transcatheter heart valves. BACKGROUND: The Evolut PRO (Medtronic, Minneapolis, MN) transcatheter aortic valve is a self-expanding transcatheter aortic valve with an outer pericardial wrap, designed to minimize paravalvular regurgitation. METHODS: Between July 2017 and December 2018, clinical, procedural, and 30-day outcome data were prospectively collected from all patients receiving the Evolut PRO valve across nine participating centers in the United Kingdom and Ireland. The primary efficacy outcome was the Valve Academic Research Consortium-2 (VARC-2)-defined endpoint of device success. The primary safety outcome was the VARC-2-defined composite endpoint of early safety at 30 days. RESULTS: A total of 317 patients underwent implantation. Mean age was 81.8 ± 6.4 years and Society of Thoracic Surgeons Predicted Risk of Mortality Score 5.5 ± 1.8%. Iliofemoral access was used in 99.1% of patients. Device success was 91.2%. Mean gradient was 7.6 ± 4.7 mmHg and effective orifice area 1.9 ± 0.7 cm2 . The incidence of moderate paravalvular regurgitation was 1.7% and there was no severe paravalvular regurgitation. A new permanent pacemaker was implanted in 17.8% of patients without a pacemaker at baseline. Early safety was demonstrated in 92.7%. At 30 days, all-cause mortality was 0.6%, stroke 3.8%, and major vascular complication 2.8%. CONCLUSIONS: Real-world experience of the Evolut PRO transcatheter aortic valve demonstrated favorable procedural success, safety, valve function, and incidence of new permanent pacemaker implantation.

Reversible PCET and Ambient Catalytic Oxidative Alcohol Dehydrogenation by {V=O} Perfluoropinacolate Complexes.

A new air-stable catalyst for the oxidative dehydrogenation of benzylic alcohols under ambient conditions has been developed. The synthesis and characterization of this compound and the related monomeric and dimeric V(IV)- and V(V)-pinF (pinF = perfluoropinacolate) complexes are reported herein. Monomeric V(IV) complex (Me4N)2[V(O)(pinF)2] (1) and dimeric (µ-O)2-bridged V(V) complex (Me4N)2[V2(O)2(µ-O)2(pinF)2] (3a) are prepared in water under ambient conditions. Monomeric V(V) complex (Me4N)[V(O)(pinF)2] (2) may be generated via chemical oxidation of 1 under an inert atmosphere, but dimerizes to 3a upon exposure to air. Complexes 1 and 2 display a perfectly reversible VIV/V couple at 20 mV (vs Ag/AgNO3), whereas a quasi-reversible VIV/V couple at -865 mV is found for 3a. Stoichiometric reactions of 3a with both fluorenol and TEMPOH result in the formation of (Me4N)2[V2(O)2(µ-OH)2(pinF)2] (4a), which contains two V(IV) centers that display antiferromagnetic coupling. In order to structurally characterize the dinuclear anion of 4a, {K(18C6)}+ countercations were employed, which formed stabilizing K···O interactions between the counterion and each terminal oxo moiety and H-bonding between the oxygen atoms of the crown ether and µ-OH bridges of the dimer, resulting in {K(18C6)}2[V2(O)2(µ-OH)2(pinF)2] (4b). The formal storage of H2 in 4a is reversible and proton-coupled electron transfer (PCET) from crystals of 4a regenerates 3a upon exposure to air over the course of several days. Furthermore, the reaction of 3a (2%) under ambient conditions with excess fluorenol, cinnamyl alcohol, or benzyl alcohol resulted in the selective formation of fluorenone (82% conversion), cinnamaldehyde (40%), or benzaldehyde (7%), respectively, reproducing oxidative alcohol dehydrogenation (OAD) chemistry known for VOx surfaces and demonstrating, in air, the thermodynamically challenging selective oxidation of alcohols to aldehydes/ketones.

Severe catheter kinking and entrapment during transradial coronary angiography: percutaneous retrieval using a sheathless guide catheter.

The transradial (TR) approach for coronary angiography and intervention is increasingly used worldwide because of several advantages such as reduced bleeding and vascular complications. During TR procedures, aggressive catheter manipulation in the setting of complex and tortuous arterial anatomy can lead to catheter kinking and entrapment. Several percutaneous retrieval techniques using either homolateral radial access or femoral access have been described previously. We demonstrate, for the first time, the use of a sheathless guide catheter as a rescue technique to successfully retrieve a severely kinked and entrapped diagnostic catheter during TR access. © 2014 Wiley Periodicals, Inc.

Arterial access site utilization in cardiogenic shock in the United Kingdom: is radial access feasible?

BACKGROUND: Cardiogenic shock (CS) remains the leading cause of mortality in patients hospitalized with acute myocardial infarction (AMI). The transradial access site (TRA) has become increasingly adopted as a default access site for percutaneous coronary intervention (PCI); however, even in experienced centers that favor the radial artery as the primary access site during PCI, patients presenting in CS are often treated via the transfemoral access site (TFA); and commentators have suggested that CS remains the final frontier that has given even experienced radial operators pause. We studied the use of TRA in patients presenting in CS in a nonselected high-risk cohort from the British Cardiovascular Intervention database over a 7-year period (2006-2012). METHODS: Mortality (30-day) and major adverse cardiac and cerebrovascular events (a composite of in-hospital mortality, in-hospital myocardial reinfarction, target vessel revascularization, and cerebrovascular events) were studied based on TFA and TRA utilization in CS patients. The influence of access site selection was studied in 7,231 CS patients; TFA was used in 5,354 and TRA in 1,877 patients. RESULTS: Transradial access site was independently associated with a lower 30-day mortality (hazard ratio [HR] 0.56, 95% CI 0.46-0.69, P = 0 < .001), in-hospital major adverse cardiac and cerebrovascular events (HR 0.64, 95% CI 0.53-0.76, P < .0001) and major bleeding (HR 0.37, 95% CI 0.18-0.73, P = .004). CONCLUSIONS: Although the majority of PCI cases performed in patients with cardiogenic shock in the United Kingdom are performed through the TFA, the radial artery represents an alternative viable access site in this high-risk cohort of patients in experienced centers.

Stent fracture: Insights on mechanisms, treatments, and outcomes from the food and drug administration manufacturer and user facility device experience database.

OBJECTIVES: Stent fracture (SF) is an uncommon complication following percutaneous coronary intervention. Previous studies of SF have either been small single-center studies or have reported data mainly from first generation platforms. The FDA MAUDE database was used to identify cases of SF to gain mechanistic insight into procedural and anatomical factors predisposing to this complication, to define treatment and associated clinical outcomes in contemporary and first generation stent platforms. METHODS AND RESULTS: Using defined search terms, 376 unique reports of SF were identified in the FDA MAUDE database of which 336 (89.4%) occurred in first generation stent platforms with 96.1% occurring in the Cypher platform. The remaining 40 reports (10.6%) occurred with a similar distribution of cases across different contemporary platforms. Common vessel characteristics associated with SF included calcification, tortuosity, stent overlap, and significant angulation with the most common modality of presentation being in-stent restenosis or stent thrombosis. CONCLUSIONS: SF occurs most commonly in first generation Cypher stents with a similar distribution of cases across different contemporary platforms. Optimal treatment strategy remains unclear with the decision to treat and the modality of treatment utilized depending on the type and severity of SF.

Sigma Receptor Ligands Are Potent Antiprion Compounds that Act Independently of Sigma Receptor Binding.

Prion diseases are invariably fatal neurodegenerative diseases of humans and other animals for which there are no effective treatment options. Previous work from our laboratory identified phenethylpiperidines as a novel class of anti-prion compounds. While working to identify the molecular target(s) of these molecules, we unexpectedly discovered ten novel antiprion compounds based on their known ability to bind to the sigma receptors, σ1R and σ2R, which are currently being tested as therapeutic or diagnostic targets for cancer and neuropsychiatric disorders. Surprisingly, however, knockout of the respective genes encoding σ1R and σ2R (Sigmar1 and Tmem97) in prion-infected N2a cells did not alter the antiprion activity of these compounds, demonstrating that these receptors are not the direct targets responsible for the antiprion effects of their ligands. Further investigation of the most potent molecules established that they are efficacious against multiple prion strains and protect against downstream prion-mediated synaptotoxicity. While the precise details of the mechanism of action of these molecules remain to be determined, the present work forms the basis for further investigation of these compounds in preclinical studies. Given the therapeutic utility of several of the tested compounds, including rimcazole and haloperidol for neuropsychiatric conditions, (+)-pentazocine for neuropathic pain, and the ongoing clinical trials of SA 4503 and ANAVEX2-73 for ischemic stroke and Alzheimer's disease, respectively, this work has immediate implications for the treatment of human prion disease.

Clinical Impact of Standardized TAVR Technique and Care Pathway: Insights From the Optimize PRO Study.

BACKGROUND: Procedural success and clinical outcomes after transcatheter aortic valve replacement (TAVR) have improved, but residual aortic regurgitation (AR) and new permanent pacemaker implantation (PPI) rates remain variable because of a lack of uniform periprocedural management and implantation. OBJECTIVES: The Optimize PRO study evaluates valve performance and procedural outcomes using an "optimized" TAVR care pathway and the cusp overlap technique (COT) in patients receiving the Evolut PRO/PRO+ (Medtronic) self-expanding valves. METHODS: Optimize PRO, a nonrandomized, prospective, postmarket study conducted in the United States, Canada, Europe, Middle East, and Australia, is enrolling patients with severe symptomatic aortic stenosis and no pre-existing pacemaker. Sites follow a standardized TAVR care pathway, including early discharge and a conduction disturbance management algorithm, and transfemoral deployment using the COT. RESULTS: A total of 400 attempted implants from the United States and Canada comprised the main cohort of this second interim analysis. The mean age was 78.7 ± 6.6 years, and the mean Society of Thoracic Surgeons predictive risk of mortality was 3.0 ± 2.4. The median length of stay was 1 day. There were no instances of moderate or severe AR at discharge. At 30 days, all-cause mortality or stroke was 3.8%, all-cause mortality was 0.8%, disabling stroke was 0.7%, hospital readmission was 10.1%, and cardiovascular rehospitalization was 6.1%. The new PPI rate was 9.8%, 5.8% with 4-step COT compliance. In the multivariable model, right bundle branch block and the depth of the implant increased the risk of PPI, whereas using the 4-step COT lowered 30-day PPI. CONCLUSIONS: The use of the TAVR care pathway and COT resulted in favorable clinical outcomes with no moderate or severe AR and low PPI rates at 30 days while facilitating early discharge and reproducible outcomes across various sites and operators. (Optimize PRO; NCT04091048).

Iatrogenic coronary dissection causing flush side branch occlusion: use of intravascular ultrasound to reopen vessel.

Iatrogenic complications present a major challenge to the interventional cardiologist. We describe a case of extensive right coronary artery dissection caused by engagement of a 0.035" guidewire. Attempts to reopen the flush-occluded posterior descending artery using conventional methods were unsuccessful. However, the vessel was successfully restored with the use of intravascular ultrasound guidance and we describe the steps involved in this technique.

Routine early coronary angioplasty versus ischaemia-guided angioplasty after thrombolysis in acute ST-elevation myocardial infarction: a meta-analysis.

AIMS: Prompt coronary reperfusion following acute ST-segment elevation myocardial infarction is pivotal to survival. Primary angioplasty is the gold standard in restoring reperfusion, but thrombolysis needs consideration when optimal call to balloon time is not feasible. Following lysis and with evolving pharmacoinvasive therapies, the advantage of routine, early percutaneous coronary intervention (PCI) over standard ischaemia-guided PCI remains debatable. We meta-analysed studies comparing these two interventional strategies. METHODS AND RESULTS: A MEDLINE search for randomized control studies was performed using the search terms 'coronary, thrombolysis, early or immediate stenting, and acute ST-elevation myocardial infarction'. Further, relevant studies were identified from global cardiovascular scientific sessions/congresses. Two interventional strategies were studied in 3195 patients in eight trials and meta-analysed using a random effects model. The combined endpoint of 30-day mortality, re-infarction, and ischaemia was reached in 106/1487 (7.3%) patients in the routine early PCI group and in 199/1470 (13.5%) patients in the ischaemia-guided PCI group following lysis with odds ratio (OR) 0.47 [95% confidence interval (CI), 0.32-0.68, P < 0.0001] favouring routine early PCI, driven by significant reduction in both re-infarction OR 0.62 (95% CI, 0.42-0.90, P < 0.011) and ischaemia OR 0.21 (95% CI, 0.10-0.47, P < 0.001). Thirty-day mortality or major bleeding rates between strategies were not significantly different. CONCLUSION: Where primary PCI is not feasible, our meta-analysis favours routine early PCI within 24 h of thrombolysis for acute ST-elevation myocardial infarction-a strategy that is safe and a time-target that is easily achievable. Early PCI is associated with reduced recurrence of ischaemia and re-infarction, but at no increased risk of major haemorrhage.

Chest Pain Post-Transcatheter Aortic Valve Implantation: Don't Forget the Uncommon Complication.

Transesophageal echocardiography guides a range of structural heart disease interventions, especially in older adult and frail patients who are deemed not suitable to undergo surgical repair. Although rare, transesophageal echocardiography can be associated with esophageal trauma, including perforation. Treating physicians should be cognizant of such a complication. (Level of Difficulty: Intermediate.).

The use of a guide catheter extension system as an aid during transradial percutaneous coronary intervention of coronary artery bypass grafts.

AIMS: Prior coronary artery bypass graft (CABG) surgery is one of the main predictors of failure of transradial PCI. Frequently this is due to difficulty in graft cannulation and/or poor backup support. In addition to Proxis's™ embolic protection role, the Proxis™, Heartrail™, and GuideLiner™ guide catheter extension devices have all been shown to facilitate coronary intervention by increasing backup support and aiding stent delivery. We describe our institution's experiences using these devices to aid transradial graft intervention. METHODS: Between October 2007 and March 2010, the utility and safety of these devices were assessed in consecutive transradial graft intervention procedures. Proxis™ cases used for proximal protection alone were excluded. Deep intubation was defined as an intubation depth of ≥2 cm. RESULTS: Guide catheter extensions were used in 33 of 41 transradial graft interventions identified. Proxis™ was used for proximal protection alone in 3 cases, leaving 30 cases as the study group (Heartrail™ n = 18, GuideLiner™ n = 3, Proxis™ n = 9). In all study cases procedural success with final TIMI-3 flow was achieved. Guide catheter extensions were used to aid during graft cannulation (n = 11), to improve backup support via deep intubation (n = 26) and as an adjunctive aspiration device (n = 11). Filter-based distal embolic protection devices were used in 11/21 Heartrail™ and GuideLiner™ cases. Deep intubation depths ranged from 30 to 138 mm (mean 61 mm) with no complications related to deep intubation seen. CONCLUSIONS: The use of guide catheter extension systems facilitated transradial graft intervention via several mechanisms including aid to graft cannulation, increasing backup support, and as an adjunctive aspiration device.

A comparison of drug-eluting stents versus bare metal stents in saphenous vein graft PCI outcomes: a meta-analysis.

AIMS: Studies demonstrate that percutaneous coronary intervention (PCI) with drug-eluting stents (DES) is associated with reduced revascularization and major adverse cardiac events (MACE) rates compared to bare metal stents (BMS) in native coronary vessels. Optimal PCI treatment of saphenous vein graft (SVG) lesions remains unclear despite SVG procedures representing up to 10% of PCI cases. We therefore performed a meta-analysis to compare outcomes between BMS and DES in SVG PCI. METHODS AND RESULTS: A search (2004-2009) of MEDLINE and conference proceedings for all relevant studies comparing mortality and MACE outcomes in DES versus BMS in SVG PCI and meta-analysis of the data was performed. Twenty studies were identified from 2005 to 2009 enrolling a total of 5,296 patients. Meta-analysis revealed a decrease in mortality associated with DES use, odds ratio (OR) 0.68; 95% confidence interval (CI) 0.53-0.88; P = 0.004. Similarly, MACE (OR 0.64; 95% CI 0.51-0.82; P < 0.001), total lesion revascularization (OR 0.60; 95% CI 0.43-0.83; P = 0.002), and total vessel revascularization (OR 0.57; 95% CI 0.41-0.80; P = 0.001) were significantly decreased in the patients in which DES were used compared to BMS. This reduction in mortality and MACE events associated with DES use appears to be limited to registry studies and not randomized controlled studies. CONCLUSIONS: Our meta-analysis suggests DES use to be safe in SVG PCI and associated with reduced mortality and MACE rates with reductions in revascularization also observed.

Transcatheter Aortic Valve Replacement via the Right Subclavian Artery Approach: A Case Series.

The right subclavian artery (RSA) approach is an infrequently used alternative-access method for transcatheter aortic valve replacement (TAVR), which may be considered when transfemoral and left subclavian artery (LSA) access routes are contraindicated. The double arterial bend encountered along the course of the RSA to the aortic root makes advancement of the TAVR delivery system more challenging, but can be overcome using a steerable delivery system over an ultra-stiff guidewire. We report 5 cases from our institution of TAVRs performed via the RSA approach in patients with severe aortic stenosis that were unsuitable for transfemoral or LSA access. The procedures were performed under general anesthesia, using a 5-cm infraclavicular incision. In each case, an Edwards Commander Delivery System was advanced through an eSheath over an Innowi guidewire, and an Edwards SAPIEN 3 valve was successfully deployed. The mean fluoroscopy time was 19.5 ± 3.8 minutes. No aortic regurgitation (AR) was present postprocedure for 4 out of 5 cases, and 1 had mild to moderate AR. The length of hospital stay was 2 to 3 days for 4 patients. All patients had an excellent outcome at 12 months post-procedure. The RSA approach is a safe and feasible access method for TAVR, and we recommend that it be considered as the next best access method if transfemoral and LSA approaches are unsuitable.

Distal stent delivery with Guideliner catheter: first in man experience.

Failure to deliver stents is one of the commonest causes of procedural failure in contemporary PCI practice. We describe successful use of the Guideliner catheter, the first purpose designed FDA and CE marked device delivery catheter in 13 complex cases in native coronary vessels and bypass grafts performed via the radial route to enable distal stent delivery following failure of conventional techniques. We discuss how the Guideliner catheter may be used to facilitate difficult radial cases.

Use of the sheathless guide catheter during routine transradial percutaneous coronary intervention: a feasibility study.

OBJECTIVE: The aim of this study is to investigate the feasibility of using a 6.5 Fr sheathless guide catheter as a default system in transradial (TRA) percutaneous coronary intervention (PCI). BACKGROUND: TRA PCI has been shown to reduce mortality rates through a reduction in access site related bleeding complications compared with procedures performed though a femoral approach. Complications associated with the TRA route increase with the size of sheath used. These complications may be reduced by the use of a sheathless guide catheter system (Asahi Intecc, Japan) that is 1-2 Fr sizes smaller in diameter than the corresponding introducer sheath. METHODS: We performed PCI in 100 consecutive cases using 6.5 Fr sheathless guides to determine the procedural success, rates of symptomatic radial spasm and radial occlusion. RESULTS: Procedural success using the 6.5 Fr sheathless guide catheter system was 100% with no cases requiring conversion to a conventional guide and catheter system. There were no procedural complications recorded associated with the use of the catheter. Adjunctive devices used in this cohort included IVUS, stent delivery catheters, distal protection devices, and simple thrombectomy catheters. The rate of radial spasm was 5% and the rate of radial occlusion at 2 months was 2%. CONCLUSION: Use of the 6.5 Fr sheathless guide catheter system, which has an outer diameter <5 Fr sheath, as the default system in routine PCI is feasible with a high rate of procedural success via the radial artery.

Development and validation of a clinical risk score to predict mortality after percutaneous coronary intervention.

OBJECTIVE: To develop and validate a contemporary clinical risk score to predict mortality after percutaneous coronary intervention (PCI). METHODS: Using data collected from patients undergoing PCI at the South Yorkshire Cardiothoracic Centre, Sheffield, UK, between January 2007 and September 2013, a risk score was developed to predict mortality. Logistic regression was used to evaluate the effect of each variable upon 30-day mortality. A backwards stepwise logistic regression model was then used to build a predictive model. The results were validated both internally and externally with data from Manchester Royal Infirmary, UK. 30-Day mortality status was determined from the UK Office of National Statistics. RESULTS: The development data set comprised 6522 patients from Sheffield. Five risk factors, including cardiogenic shock, procedural urgency, history of renal disease, diabetes mellitus and age, were statistically significant to predict 30-day mortality. The risk score was validated internally on a further 3290 patients from Sheffield and externally on 3230 patients from Manchester. The discrimination of the model was high in the development (C-statistic=0.82, 95% CI 0.79 to 0.85), internal (C-statistic=0.81, 95% CI 0.76 to 0.86) and external (C statistics=0.90, 95% CI 0.87 to 0.93) cohorts. There was no significant difference between observed and predicted mortality in any group. CONCLUSION: This contemporary risk score reliably predicts 30-day mortality after PCI using a small number of clinical variables obtainable prior to the procedure, without knowledge of the coronary anatomy.

Longitudinal deformation bench testing using a coronary artery model: a new standard?

Objectives: To compare susceptibility of five different stent platforms with longitudinal stent deformation (LSD) using a clinically relevant bench testing model simulating both short and long malapposed lengths. Background: Recent data suggest that design modifications to the Promus Element stent which led to the Promus Premier stent has reduced susceptibility to LSD. However, susceptibility to LSD at long malapposed lengths has not been tested. Furthermore, the mechanisms behind susceptibility to LSD are as yet unclear. Methods: The Omega, Integrity, Multilink 8, Biomatrixand Promus Premier stent platforms were tested. The Omega, Integrity and Multilink 8 platforms were used in place of their drug-eluting equivalents. 3.5 mm stents were deployed in a stepped tube with the distal portion fixed and the proximal test section exposed. The force required to compress stents by a fixed distance at different exposed lengths was compared. Symmetrical and point loading were used. Results: The Promus Premier was longitudinally as strong as Multilink and Integrity at a short exposed length (4 mm) but weaker, in between Omega and the other platforms, at longer exposed lengths (12 mm). As previously noted, the Omega (Promus Element) platform was significantly weaker than the other stents and Biomatrix was the strongest stent. Conclusion: Susceptibility to LSD varies depending on length of malapposed segment when tested using a clinically relevant model as in this study. The mechanisms behind the susceptibility are likely multifactorial, including connector number, strut thickness, connector alignment and ring orientation but remain to be elucidated.

Nanometre-thick single-crystalline nanosheets grown at the water-air interface.

To date, the preparation of free-standing 2D nanomaterials has been largely limited to the exfoliation of van der Waals solids. The lack of a robust mechanism for the bottom-up synthesis of 2D nanomaterials from non-layered materials has become an obstacle to further explore the physical properties and advanced applications of 2D nanomaterials. Here we demonstrate that surfactant monolayers can serve as soft templates guiding the nucleation and growth of 2D nanomaterials in large area beyond the limitation of van der Waals solids. One- to 2-nm-thick, single-crystalline free-standing ZnO nanosheets with sizes up to tens of micrometres are synthesized at the water-air interface. In this process, the packing density of surfactant monolayers adapts to the sub-phase metal ions and guides the epitaxial growth of nanosheets. It is thus named adaptive ionic layer epitaxy (AILE). The electronic properties of ZnO nanosheets and AILE of other materials are also investigated.