Prosthetic heart valves: Objective Performance Criteria versus randomized clinical trial

Standardized approach to extract candidate outcomes from literature for a standard outcome set: a case- and simulation study

AIMS

Standard outcome sets enable the value-based evaluation of health care delivery. Whereas the attainment of expert opinion has been structured using methods such as the modified-Delphi process, standardized guidelines for extraction of candidate outcomes from literature are lacking. As such, we aimed to describe an approach to obtain a comprehensive list of candidate outcomes for potential inclusion in standard outcome sets.

METHODS

This study describes an iterative saturation approach, using randomly selected batches from a systematic literature search to develop a long list of candidate outcomes to evaluate healthcare. This approach can be preceded with an optional benchmark review of relevant registries and Clinical Practice Guidelines and data visualization techniques (e.g. as a WordCloud) to potentially decrease the number of iterations. The development of the International Consortium of Health Outcome Measures Heart valve disease set is used to illustrate the approach. Batch cutoff choices of the iterative saturation approach were validated using data of 1000 simulated cases.

RESULTS

Simulation showed that on average 98% (range 92-100%) saturation is reached using a 100-article batch initially, with 25 articles in the subsequent batches. On average 4.7 repeating rounds (range 1-9) of 25 new articles were necessary to achieve saturation if no outcomes are first identified from a benchmark review or a data visualization.

CONCLUSION

In this paper a standardized approach is proposed to identify relevant candidate outcomes for a standard outcome set. This approach creates a balance between comprehensiveness and feasibility in conducting literature reviews for the identification of candidate outcomes.

Most endovascular thrombectomy patients have Target Mismatch despite absence of formal CT perfusion selection criteria

Endovascular thrombectomy (EVT) is the standard of care for large vessel occlusion stroke. Use of Computed Tomographic Perfusion (CTP) to select EVT candidates is variable. The frequency of treatment and outcome in patients with unfavourable CTP patterns is unknown. A retrospective analysis of CTP utilisation prior to EVT was conducted. All CTP data were analysed centrally and a Target Mismatch was defined as an infarct core ≤70 ml, penumbral volume ≥15ml, and a total hypoperfused volume:core volume ratio >1.8. The primary outcome was good functional outcome at 90 days, defined as a modified Rankin Scale (mRS) score 0-2. follow-up infarct volume, core expansion and penumbral salvage volumes were secondary outcomes. Of 572 anterior circulation EVT patients, CTP source image data required to generate objective maps were available in 170, and a Target Mismatch was present in 151 (89%). The rate of 90-day good functional outcome was similar between Target Mismatch (53%) and Large Core Non-Mismatch groups (46%, p = 0.629). Median follow-up infarct volume in the Large Core Non-Mismatch group (104ml [IQR 25ml-189ml]) was larger than that in the Target Mismatch patients (16ml [8ml-47ml], p<0.001). Despite a lack of formal CTP selection criteria, the majority of patients treated at our centres had a Target Mismatch. Patients without Target Mismatch had larger follow-up infarct volumes, but the functional recovery rate was similar to that in Target Mismatch patients. Infarct volumes should be included as objective assessment criteria in the evaluation of the efficacy of EVT in non-Target Mismatch patients.

Association of nanoparticles and Nrf2 with various oxidative stress-mediated diseases

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regultes the cellular antioxidant defense system at the posttranscriptional level. During oxidative stress, Nrf2 is released from its negative regulator Kelch-like ECH-associated protein 1 (Keap1) and binds to antioxidant response element (ARE) to transcribe antioxidative metabolizing/detoxifying genes. Various transcription factors like aryl hydrocarbon receptor (AhR) and nuclear factor kappa light chain enhancer of activated B cells (NF-kB) and epigenetic modification including DNA methylation and histone methylation might also regulate the expression of Nrf2. Despite its protective role, Keap1/Nrf2/ARE signaling is considered as a pharmacological target due to its involvement in various pathophysiological conditions such as diabetes, cardiovascular disease, cancer, neurodegenerative diseases, hepatotoxicity and kidney disorders. Recently, nanomaterials have received a lot of attention due to their unique physiochemical properties and are also used in various biological applications, for example, biosensors, drug delivery systems, cancer therapy, etc. In this review, we will be discussing the functions of nanoparticles and Nrf2 as a combined therapy or sensitizing agent and their significance in various diseases such as diabetes, cancer and oxidative stress-mediated diseases.

Toxicological Aspects, Safety Assessment, and Green Toxicology of Silver Nanoparticles (AgNPs)—Critical Review: State of the Art

In recent years, research on silver nanoparticles (AgNPs) has attracted considerable interest among scientists because of, among other things, their alternative application to well-known medical agents with antibacterial properties. The size of the silver nanoparticles ranges from 1 to 100 nm. In this paper, we review the progress of research on AgNPs with respect to the synthesis, applications, and toxicological safety of AgNPs, and the issue of in vivo and in vitro research on silver nanoparticles. AgNPs’ synthesis methods include physical, chemical, and biological routes, as well as “green synthesis”. The content of this article covers issues related to the disadvantages of physical and chemical methods, which are expensive and can also have toxicity. This review pays special attention to AgNP biosafety concerns, such as potential toxicity to cells, tissues, and organs.

Green synthesis of silver nanoparticles and their antibacterial effects

Antibacterial resistance is by far one of the greatest challenges to global health. Many pharmaceutical or material strategies have been explored to overcome this dilemma. Of these, silver nanoparticles (AgNPs) are known to have a non-specific antibacterial mechanism that renders it difficult to engender silver-resistant bacteria, enabling them to be more powerful antibacterial agents than conventional antibiotics. AgNPs have shown promising antibacterial effects in both Gram-positive and Gram-negative bacteria. The aim of this review is to summarize the green synthesis of AgNPs as antibacterial agents, while other AgNPs-related insights (e.g., antibacterial mechanisms, potential toxicity, and medical applications) are also reviewed.

Creation of objective performance criteria among medical devices

Objectives

Objective performance criteria (OPC) may serve as a tool to expedite the approval process and continue active surveillance of class III medical devices. Thus far, published guidance on the creation of OPC has been clinical area-specific. This study aimed to capture reflections from key stakeholders on the creation of OPC that may serve as a precursor for a formalized conceptual framework within the USA.

Design

Reflections from key stakeholders and guidance from an advisory committee were captured to gain an understanding of the elements that are crucial to the generation of OPC.

Setting

A non-probability sampling method using the purposive sampling strategy was employed to identify relevant stakeholders for engagement in semi-structured, open-ended, concept elicitation discussions.

Participants

Stakeholders involved in the generation of OPC.

Main outcome measures

Elements and themes regarding the priorities of, experiences with, roles within and perceived challenges associated with OPC creation captured through a phenomenological approach.

Results

A total of 27 participants were engaged to represent the following contributors: representatives of registries, health systems, health technology assessment bodies, clinicians, device application reviewers, payers, patients, patient representatives, patient caregivers, device manufacturers, data coordinators, data analysts and data informaticians. Consensus was achieved on the five core elements: (1) identification of medical devices, (2) engagement of key stakeholders, (3) selection of data source, (4) performance of appropriate statistical analyses and (5) reporting of findings. The engagement of key stakeholders (38%) was cited most frequently as the most important core element. Access to meaningful and high-quality data sources (47%) was the most frequently mentioned challenge.

Conclusions

The reflections from the participants identified five elements to be considered when generating an OPC within class III medical devices and may provide the needed foundation for the development of official guidance on OPC generation.

Protocol for LASER: A Randomized Evaluation and an Associated Registry of Early Anticoagulation With Edoxaban After Ischemic Stroke in Patients With Atrial Fibrillation

Background: The optimal timing of anticoagulation after stroke in patients with atrial fibrillation (AF) is unknown.

Aim and Hypothesis: Our primary aim is to demonstrate the safety of edoxaban initiation within 5 days of AF related stroke. Our secondary aim is to determine predictors of hemorrhagic transformation (HT) after AF related stroke. We hypothesize that the rate of radiological HT will not be increased in patients starting edoxaban within 5 days of AF related stroke, relative to those in whom initiation is delayed. We hypothesize that the risk of HT in patients treated with edoxaban can be predicted using RNA expressed in leukocytes at time of stroke.

Methods and Design: LASER (Lixiana Acute Stroke Evaluation Registry) is a randomized controlled trial with an associated registry (clinicaltrials.gov NCT03494530). One hundred and fifty patients with ischemic stroke and AF will undergo baseline Computed Tomography (CT) scan and will be randomized 2:1 within 5 days of symptom onset to early (≤5 days, n = 100) or delayed (6–14 days, n = 50) edoxaban initiation. Participants will undergo clinical assessment and repeat CT at 7 days and clinical assessment at 90 days.

Study Outcomes: The primary outcome is the rate of incident radiological HT. Secondary outcomes include symptomatic HT, recurrent ischemic stroke, recurrent sub-clinical infarcts on follow up CT, systemic hemorrhagic complication rate, National Institute of Health Stroke Scale and modified Rankin Scale at day 7 and 90, mortality within 90 days, quality of life assessments at day 90, and predictors of HT, including RNA expression by 6 pre-selected candidate genes.

Discussion: Event rates for both HT and recurrent ischemic events, in patients treated with early vs. delayed edoxaban initiation are unknown. The primary study endpoint of LASER is an objective performance criterion relevant to clinical decision making in patients with AF related stroke. This study will provide data required for a definitive safety/efficacy study sample size power calculation.

Phyto-fabrication, purification, characterisation, optimisation, and biological competence of nano-silver

Published studies indicate that virtually any kind of botanical material can be exploited to make biocompatible, safe, and cost-effective silver nanoparticles. This hypothesis is supported by the fact that plants possess active bio-ingredients that function as powerful reducing and coating agents for Ag+. In this respect, a phytomediation method provides favourable monodisperse, crystalline, and spherical particles that can be easily purified by ultra-centrifugation. However, the characteristics of the particles depend on the reaction conditions. Optimal reaction conditions observed in different experiments were 70-95 °C and pH 5.5-8.0. Green silver nanoparticles (AgNPs) have remarkable physical, chemical, optical, and biological properties. Research findings revealed the versatility of silver particles, ranging from exploitation in topical antimicrobial ointments to in vivo prosthetic/organ implants. Advances in research on biogenic silver nanoparticles have led to the development of sophisticated optical and electronic materials with improved efficiency in a compact configuration. So far, eco-toxicity of these nanoparticles is a big challenge, and no reliable method to improve the toxicity has been reported. Therefore, there is a need for reliable models to evaluate the effect of these nanoparticles on living organisms.

Early apixaban therapy after ischemic stroke in patients with atrial fibrillation

BACKGROUND

The optimal timing of anticoagulation after stroke in patients with atrial fibrillation (AF) is unknown. We aimed to objectively assess the rate of radiological hemorrhagic transformation (HT) associated with early anticoagulation.

PATIENTS AND METHODS

A prospective, open label study (NCT04435418) of patients with AF treated with apixaban within 14 days of ischemic stroke/TIA onset was conducted. Baseline and follow-up CT scans were assessed for HT and graded using European Cooperative Acute Stroke Study (ECASS) criteria. The primary endpoint was symptomatic HT. Incident HT rates were assessed as Objective Performance Criteria.

RESULTS

One-hundred AF stroke patients, with a mean age of 79 ± 11 years were enrolled. Median infarct volume was 4 (0.5-10.75) ml. Median time from index event onset to apixaban initiation was 2 (1-6) days, and median baseline NIHSS was 4 (1-9). Asymptomatic HT on baseline imaging was present in 15 patients. Infarct volume (OR = 1.1, [1.02-1.12], p < 0.0001) and NIHSS (OR = 1.11, [1.03-1.20], p = 0.007) were both associated with baseline HT. No patients developed symptomatic HT or systemic hemorrhage. Incident asymptomatic HT was seen on follow-up CT scan in 3 patients. Patients with incident HT were functionally independent (mRS = 0-2) at 90 days. Recurrent ischemic events occurred within 90 days in 13 patients, 4 of which were associated with severe disability (mRS 3-5) and 4 with death.

DISCUSSION

Early apixaban treatment did not precipitate symptomatic HT after stroke. All HT was asymptomatic identified on imaging. Recurrent ischemic events were common and clinically symptomatic.

CONCLUSIONS

Symptomatic HT rates are likely to be low in randomized trials of DOAC initiation post-stroke. Recurrent ischemic stroke may be the major clinical outcome. These data may be used as expected event rates when calculating sample size requirements for future safety/efficacy trials of early versus late DOAC initiation after AF-related stroke.

Antibacterial Activity of Silver and Its Application in Dentistry, Cardiology and Dermatology

The problem of antimicrobial resistance is increasingly present and requires the discovery of new antimicrobial agents. Although the healing features of silver have been recognized since ancient times, silver has not been used due to newly discovered antibiotics. Thanks to technology development, a significant step forward has been made in silver nanoparticles research. Nowadays, silver nanoparticles are a frequent target of researchers to find new and better drugs. Namely, there is a need for silver nanoparticles as alternative antibacterial nanobiotics. Silver nanoparticles (AgNPs), depending on their size and shape, also have different antimicrobial activity. In addition to their apparent antibacterial activity, AgNPs can serve as drug delivery systems and have anti-thrombogenic, anti-platelet, and anti-hypertensive properties. Today they are increasingly used in clinical medicine and dental medicine. This paper presents silver antimicrobial activity and its use in dentistry, cardiology, and dermatology, where it has an extensive range of effects.

A review on green synthesis of silver nanoparticles and their applications

Development of reliable and eco-accommodating methods for the synthesis of nanoparticles is a vital step in the field of nanotechnology. Silver nanoparticles are important because of their exceptional chemical, physical, and biological properties, and hence applications. In the last decade, numerous efforts were made to develop green methods of synthesis to avoid the hazardous byproducts. This review describes the methods of green synthesis for Ag-NPs and their numerous applications. It also describes the comparison of efficient synthesis methods via green routes over physical and chemical methods, which provide strong evidence for the selection of suitable method for the synthesis of Ag-NPs.

Recent Nanotechnology Approaches for Prevention and Treatment of Biofilm-Associated Infections on Medical Devices

Bacterial colonization in the form of biofilms on surfaces causes persistent infections and is an issue of considerable concern to healthcare providers. There is an urgent need for novel antimicrobial or antibiofilm surfaces and biomedical devices that provide protection against biofilm formation and planktonic pathogens, including antibiotic resistant strains. In this context, recent developments in the material science and engineering fields and steady progress in the nanotechnology field have created opportunities to design new biomaterials and surfaces with anti-infective, antifouling, bactericidal, and antibiofilm properties. Here we review a number of the recently developed nanotechnology-based biomaterials and explain underlying strategies used to make antibiofilm surfaces.

Considerations and Recommendations for the Introduction of Objective Performance Criteria for Transcatheter Aortic Heart Valve Device Approval

In the United States, new surgical heart valves can be approved on the basis of objective performance criteria (OPC). In contrast, the US Food and Drug Administration traditionally requires stricter criteria for transcatheter heart valve (THV) approval, including randomized, clinical trials. Recent US Food and Drug Administration approval of new-generation THVs based on single-arm studies has generated interest in alternative study approaches for THV device approval. This review evaluates whether THV device approval could follow a pathway analogous to that of surgical heart valves by incorporating OPC and provides several considerations and recommendations. Factors to be taken into account in the construction of OPC include the maturity of THV technology, variability in transcatheter aortic valve replacement practice, end points included as OPC, follow-up terms for specific OPC, patient populations to which these OPC apply, and (statistical) methods for OPC development. We recommend that approval of THV devices in the United States for low- and intermediate-risk patients or for new indications should provisionally rely on data from randomized, clinical trials. However, it is recommended that formal OPC be applied for approval of new-generation THVs for use in high- and extreme-risk patient populations.

An analysis of real-world cost-effectiveness of TAVI in South Africa

Objectives

Transcatheter aortic valve implantation (TAVI) has become the standard of care for inoperable patients with severe aortic stenosis and is an alternative to conventional surgery for high-risk aortic valve replacement (AVR) patients. There is a positive correlation between severity of pre-operative patients and hospital costs. The aim of this study was to compare empirically derived costs of the two therapies in South Africa.

Methods

The cost-comparison analysis was performed with a MediClinic database including 239 conventional isolated AVR (cAVR) and 75 TAVI cases. All costs are given in 2011 ZAR. The subset of cAVR patients were derived from the relevant and available information in the database and their costs were compared with TAVI costs.

Results

From the 75 available subjects, mean TAVI costs were ZAR 335.5k ± 47.9k, (median ZAR 326.5k) with a mean (median) ICU and hospital length of stay (LoS) of 2.7 (2.0) and 7.6 (6.5) days, respectively. The mean cAVR cost was lower at ZAR 213.9 ± 87.5k (median ZAR 193.6k) but this included the entire population costs (i.e. low to high surgical risk). When estimating cAVR costs, defined by LoS of more than six and 13 days in the ICU and hospital, respectively, and being over 75 years of age, the estimate increased to ZAR 337.9k, which was above the TAVI mean costs. In-hospital mortality was 5.3 and 7.9% for TAVI and the entire cAVR group, respectively. When considering the subset of cAVR patients most likely to be high risk, it increased to 21.4%.

Conclusions

Within the context of limited clinical data we performed the first attempt at cost-effective analysis of TAVI vs cAVR in South Africa. Treatment of aortic stenosis with cAVR in a post hoc defined high-risk patient segment was more expensive than TAVI in South African centres. Despite common perceptions on costs, adoption of TAVI as an alternative, less-invasive therapy that has been clinically proven and recommended by an FDA advisory panel (Partner A) to be at least as effective as cAVR, has a viable economic argument in appropriate patients.

Clinical evaluation of new heart valve prostheses: update of objective performance criteria

This article summarizes the long-term clinical results of the Food and Drug Administration-approved heart valves, provides current updates to the objective performance criteria (OPC) used to evaluate new heart valve prostheses, and documents the steps that the International Organization for Standardization Committee used to arrive at the updated OPC. Data were extracted from 19 Food and Drug Administration summaries of safety and effectiveness data reports (31 series) and 56 literature articles (85 series) published from 1999 to 2012. The OPC were calculated for five valve-related complications by valve type (mechanical and bioprosthetic) and valve position (aortic and mitral).

Nanosilver particles in medical applications: synthesis, performance, and toxicity

Nanosilver particles (NSPs), are among the most attractive nanomaterials, and have been widely used in a range of biomedical applications, including diagnosis, treatment, drug delivery, medical device coating, and for personal health care. With the increasing application of NSPs in medical contexts, it is becoming necessary for a better understanding of the mechanisms of NSPs' biological interactions and their potential toxicity. In this review, we first introduce the synthesis routes of NSPs, including physical, chemical, and biological or green synthesis. Then the unique physiochemical properties of NSPs, such as antibacterial, antifungal, antiviral, and anti-inflammatory activity, are discussed in detail. Further, some recent applications of NSPs in prevention, diagnosis, and treatment in medical fields are described. Finally, potential toxicology considerations of NSPs, both in vitro and in vivo, are also addressed.

Nanosilver particles in medical applications: synthesis, performance, and toxicity

Nanosilver particles (NSPs), are among the most attractive nanomaterials, and have been widely used in a range of biomedical applications, including diagnosis, treatment, drug delivery, medical device coating, and for personal health care. With the increasing application of NSPs in medical contexts, it is becoming necessary for a better understanding of the mechanisms of NSPs' biological interactions and their potential toxicity. In this review, we first introduce the synthesis routes of NSPs, including physical, chemical, and biological or green synthesis. Then the unique physiochemical properties of NSPs, such as antibacterial, antifungal, antiviral, and anti-inflammatory activity, are discussed in detail. Further, some recent applications of NSPs in prevention, diagnosis, and treatment in medical fields are described. Finally, potential toxicology considerations of NSPs, both in vitro and in vivo, are also addressed.

Current challenges for clinical trials of cardiovascular medical devices

Several features of cardiovascular devices raise considerations for clinical trial conduct. Prospective, randomized, controlled trials remain the highest quality evidence for safety and effectiveness assessments, but, for instance, blinding may be challenging. In order to avoid bias and not confound data interpretation, the use of objective endpoints and blinding patients, study staff, core labs, and clinical endpoint committees to treatment assignment are helpful approaches. Anticipation of potential bias should be considered and planned for prospectively in a cardiovascular device trial. Prospective, single-arm studies (often referred to as registry studies) can provide additional data in some cases. They are subject to selection bias even when carefully designed; thus, they are generally not acceptable as the sole basis for pre-market approval of high risk cardiovascular devices. However, they complement the evidence base and fill the gaps unanswered by randomized trials. Registry studies present device safety and effectiveness in day-to-day clinical practice settings and detect rare adverse events in the post-market period. No single research design will be appropriate for every cardiovascular device or target patient population. The type of trial, appropriate control group, and optimal length of follow-up will depend on the specific device, its potential clinical benefits, the target patient population and the existence (or lack) of effective therapies, and its anticipated risks. Continued efforts on the part of investigators, the device industry, and government regulators are needed to reach the optimal approach for evaluating the safety and performance of innovative devices for the treatment of cardiovascular disease.

CardiaMed mechanical valve: mid-term results of a multicenter clinical trial

BACKGROUND

Prosthesis choice is a major concern in valvular surgery.

METHODS

A multicenter clinical trial was performed to assess the efficacy and safety of the CardiaMed prosthetic heart valve. The study enrolled 420 patients who underwent mitral (209) or aortic (211) valve replacement from 2003 to 2004 at 7 institutions in Russia, and who were followed up from 2006 to 2011. The mean age was 52.2 ± 10.2 years (range, 12-78 years), 47.4% were female, and 99.05% completed the study.

RESULTS

The maximum observation term was 7.5 years (2188.5 patient-years); 1081.6 patient-years for aortic and 1106.9 patient-years for mitral valve replacement. The overall 7-year survival rate was 85.1%  ± 3.7%; 86.1%  ± 4.8% and 84.4%  ± 5.4% for aortic and mitral valve replacement, respectively. The 7-year freedom from valve-related death was 93.9%  ± 3.7% and 94.5%  ± 3.2% for aortic and mitral valve replacement, respectively. When early mortality (<30 days) was excluded, these rates were 94.8%  ± 3.1% and 93.8%  ± 3.82%, respectively. Linearized valve-dependent complication rates were determined for structural valve failure (0%/patient-year overall), thrombosis (0.63%/patient-year, all for mitral valve replacement), thromboembolic complications including transient neurologic deficits (0.13%/patient-year overall, 0.5%/patient-year for aortic valve replacement, 0.8%/patient-year for mitral valve replacement), hemorrhagic bleeding (0.64%/patient-year overall, 0.55%/patient-year for aortic valve replacement, 0.09%/patient-year for mitral valve replacement), prosthetic endocarditis (0.28%/patient-year overall, 0.28%/patient-year for aortic valve replacement, 0%/patient-year for mitral valve replacement), and hemolysis (0%/patient-year overall).

CONCLUSION

The CardiaMed mechanical heart valve prostheses meets world standards of safety and efficacy.

Sequential design for clinical trials evaluating a prosthetic heart valve

BACKGROUND

Clinical trials involving prosthetic heart valves are typically based on a set of objective performance criteria for certain late adverse event rates. Typically, these trials require 800 patient-years of data to be collected to provide 80% power while maintaining the type I error at the 0.05 level.

METHODS

This work presents a sequential design alternative to the standard objective performance criteria trial that allows for the possibility of stopping the trial early. Logistical issues regarding these designs are considered, and power calculations are provided that investigate the probability of early stopping if the prosthetic valve exceeds expectations with respect to the objective performance criteria end points.

RESULTS

Designs exist that provide at least 50% power at the interim look and 80% overall power under the alternative hypothesis. If the prosthetic valve performs better than expected, the interim power may exceed 80%.

CONCLUSIONS

The proposed sequential designs can reduce the time required to bring a prosthetic heart valve to market, helping to ensure that patients and clinicians have access to the latest devices in shorter time.

Understanding objective performance goals for critical limb ischemia trials

Critical limb ischemia (CLI), the most advanced form of peripheral arterial disease, is associated with a high rate of limb loss and substantial mortality. Revascularization remains the cornerstone of limb salvage in the CLI patient, and surgical bypass is the established standard. Endovascular therapies, such as angioplasty, atherectomy, and stenting offer a less-invasive option, but evidence of efficacy is lacking, and no devices are currently approved specifically for CLI. Design and execution of clinical trials in the CLI population are challenging, in part because of the lack of consensus on cohort definitions and relevant endpoints. Recently, the Society for Vascular Surgery undertook an initiative to define therapeutic benchmarks, objective performance goals (OPGs), for CLI. Using surgical bypass with autogenous vein as the standard for comparison, OPGs were developed for nine safety and efficacy measures that could be utilized in the premarket assessment of new devices in CLI. Data from three large randomized controlled trials of surgical bypass for CLI were analyzed. We defined a major adverse limb event (MALE) as a key endpoint for revascularization therapies in CLI--inclusive of amputation (transtibial or above) or any major vascular reintervention (thrombectomy, thrombolysis, or major surgical procedure [new bypass graft, jump/interposition graft revision]) in the index limb. Freedom from perioperative (30-day) death or any MALE (MALE + POD) was suggested as the primary efficacy endpoint for a single-arm trial design in CLI, with an observed rate of 76.9% for the surgical bypass controls at 1 year. Specific high-risk subgroups were also defined from the surgical dataset--based on clinical (age older than 80 years and tissue loss), arterial anatomy (infrapopliteal disease), and conduit quality (inadequate saphenous vein) characteristics. Risk-adjusted OPG were developed for these subgroups of interest. These OPGs define a new set of benchmarks for assessing the performance of revascularization therapies in CLI, and should facilitate clinical trial design and device development in this arena.

Nanosilver as a new generation of nanoproduct in biomedical applications

Nanosilver (NS), comprising silver nanoparticles, is attracting interest for a range of biomedical applications owing to its potent antibacterial activity. It has recently been demonstrated that NS has useful anti-inflammatory effects and improves wound healing, which could be exploited in developing better dressings for wounds and burns. The key to its broad-acting and potent antibacterial activity is the multifaceted mechanism by which NS acts on microbes. This is utilized in antibacterial coatings on medical devices to reduce nosocomial infection rates. Many new synthesis methods have emerged and are being evaluated for NS production for medical applications. NS toxicity is also critically discussed to reflect on potential concerns before widespread application in the medical field.

The future of new aortic valve replacement approaches

Aortic valve disease is a growing cause of mortality and morbidity, especially in developed countries. Whereas medical therapy is associated with an ominous prognosis, since the 1970s, surgical valve replacement has represented a standard therapy for fit patients. Indeed, this approach is safe and feasible in younger patients without comorbidities. However, in unfit patients, surgery may be associated with a very high risk. The advent of transcatheter valve replacement techniques, by means of percutaneous or transapical approaches, has been recently introduced into mainstream clinical practice and is likely to radically change the treatment of aortic valve disease. At present, further data are needed to thoroughly appraise the long-term risk-benefit balance of transcatheter valve replacement techniques. For this reason, it can only be considered for high surgical risk patients, but early results are so promising that in the future, transcatheter aortic valve implantation could became the first therapeutic choice, even for low-risk patients.

Premarket assessment of devices for treatment of critical limb ischemia: the role of Objective Performance Criteria and Goals

Medical devices are cleared for marketing approval through the Food and Drug Administration (FDA). Unique statutory requirements, such as the "least burdensome mandate," have allowed the FDA to employ non-concurrent controls in its evaluation of prospective therapies. The use of Objective Performance Criteria and Goals (OPC and OPG) for the premarket evaluation of cardiovascular devices has become established as an alternative to randomized, controlled trials (RCTs). These single-armed comparisons may facilitate rapid entry of novel devices to the market. Unlike RCTs, they do not establish superiority or non-inferiority of the examined therapy, and study populations must be carefully inspected to ensure validity of comparisons to historical controls.

INTERMACS: interval analysis of registry data

BACKGROUND

The Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) is an NIH-sponsored registry of US FDA-approved mechanical circulatory support devices (MCSDs) used for destination therapy, bridge to transplantation (BTT), or recovery of the heart. INTERMACS data were analyzed through the most recent quarter ending March 31, 2008.

STUDY DESIGN

INTERMACS variables include demographics, patient outcomes (survival and adverse events), hemodynamic data, and laboratory values. Data were analyzed with competing outcomes methods. Risk factors were identified for death and transplantation.

RESULTS

Ninety-four sites have prospectively enrolled 483 patients in INTERMACS (BTT, 80%; destination therapy, 15%; bridge to recovery, 5%). Forty-two percent of patients had critical cardiogenic shock before implantation, 38% had progressive circulatory decline despite inotropic agents, and 8% were stable but inotropic agent-dependent. The remaining 12% had recurrent advanced heart failure, severe exercise intolerance, or advanced class III heart failure. At 6 months postimplantation, the competing outcomes for the 483 patients included ongoing support (42%), cardiac transplantation (33%), cardiac recovery with pump removal (3%), or death (22%). The most common causes of death were central nervous system events (11%), cardiovascular failure (8%), or respiratory failure (8%). Less common causes were infection (4%), device malfunction (4%), and liver failure (3%). Survival for BTT and destination therapy were similar (p = 0.53). Patient profile at the time of implantation (critical cardiogenic shock versus others) influenced survival (p = 0.007), as did device configuration (left ventricular assist device versus biventricular ventricular assist device; p < 0.0001).

CONCLUSIONS

INTERMACS has increasing participation among domestic MCSD centers. The influence of preimplantation patient condition on survival underscores the importance of timely referral before critical cardiogenic shock occurs. As more devices achieve US FDA approval, INTERMACS will become useful for comparing MCSDs.

Transcatheter valve implantation for patients with aortic stenosis: a position statement from the European Association of Cardio-Thoracic Surgery (EACTS) and the European Society of Cardiology (ESC), in collaboration with the European Association of Percutaneous Cardiovascular Interventions (EAPCI)

AIMS

To critically review the available transcatheter aortic valve implantation techniques and their results, as well as propose recommendations for their use and development.

METHODS AND RESULTS

A committee of experts including European Association of Cardio-Thoracic Surgery and European Society of Cardiology representatives met to reach a consensus based on the analysis of the available data obtained with transcatheter aortic valve implantation and their own experience. The evidence suggests that this technique is feasible and provides haemodynamic and clinical improvement for up to 2 years in patients with severe symptomatic aortic stenosis at high risk or with contraindications for surgery. Questions remain mainly concerning safety and long-term durability, which have to be assessed. Surgeons and cardiologists working as a team should select candidates, perform the procedure, and assess the results. Today, the use of this technique should be restricted to high-risk patients or those with contraindications for surgery. However, this may be extended to lower risk patients if the initial promise holds to be true after careful evaluation.

CONCLUSION

Transcatheter aortic valve implantation is a promising technique, which may offer an alternative to conventional surgery for high-risk patients with aortic stenosis. Today, careful evaluation is needed to avoid the risk of uncontrolled diffusion.

From trees to wood and back: perspective on clinical data analysis in thoracic surgery

General thoracic surgery has been slow to embrace advanced statistical techniques to assess outcome and direct future therapy to individual patients (the "trees") based on aggregating data and discovering informative patterns in them (the "wood"). This is due in part to the nature and complexity of the practice. However, methods exist that deal with problems of small numbers, variable case volume, and heterogeneity of patients, diseases, and therapies. For effective analysis of these multiple variables, modern strategies must be used and pitfalls avoided. For generating new knowledge about appropriateness of therapy, the focus of analyses must include long-term outcome. Quality improvement efforts may be assisted by in-depth analysis of short-term outcome from a select number of centers to inform future universal efforts. Ultimately, these results need to feed back to improved management of the individual patient.