Bram D. Zuckerman

Myonecrosis After Revascularization Procedures

The detection of elevated cardiac enzyme levels and the occurrence of electrocardiographic (ECG) abnormalities after revascularization procedures have been the subject of recent controversy. This report represents an effort to achieve a consensus among a group of researchers with data on this subject. Creatine kinase (CK) or CK-MB isoenzyme (CK-MB) elevations occur in 5% to 30% of patients after a percutaneous intervention and commonly during coronary artery bypass graft surgery (CABG). Although Q wave formation is rare, other ECG changes are common. The rate of detection is highly dependent on the intensity of enzyme and ECG measurement. Because most events occur without the development of a Q wave, the ECG will not definitively diagnose them; even the ECG criteria for Q wave formation signifying an important clinical event have been variable. At least 10 studies evaluating > 10,000 patients undergoing percutaneous intervention have demonstrated that elevation of CK or CK-MB is associated not only with a higher mortality, but also with a higher risk of subsequent cardiac events and higher cost. Efforts to identify a specific cutoff value below which the prognosis is not impaired have not been successful. Rather, the risk of adverse outcomes increases with any elevation of CK or CK-MB and increases further in proportion to the level of intervention. This information complements similar previous data on CABG. Obtaining preprocedural and postprocedural ECGs and measurement of serial cardiac enzymes after revascularization are recommended. Patients with enzyme levels elevated more than threefold above the upper limit of normal or with ECG changes diagnostic for Q wave myocardial infarction (MI) should be treated as patients with an MI. Patients with more modest elevations should be observed carefully. Clinical trials should ensure systematic evaluation for myocardial necrosis, with attention paid to multivariable analysis of risk factors for poor long-term outcome, to determine the extent to which enzyme elevation is an independent risk factor after considering clinical history, coronary anatomy, left ventricular function and clinical evidence of ischemia. In addition, tracking of enzyme levels in clinical trials is needed to determine whether interventions that reduce periprocedural enzyme elevation also improve mortality.

Drug-Eluting Stents in Preclinical Studies: Recommended Evaluation From a Consensus Group

The arrival of drug-eluting stents raises important questions about preclinical evaluation of devices and the optimal means of predicting clinical safety and efficacy. The Interventional, Regulatory, Commercial, and Scientific communities have all asked for assistance in defining criteria for device evaluation. This document is an integrated view of requirements for evaluating drug-eluting stents in preclinical models. The suggested requirements encompass study design, experimental performance, and histopathologic evaluations, emphasizing safety and efficacy at multiple points in time. This is a consensus document assembled by clinical, academic, and industrial investigators engaged in preclinical interventional device evaluation. Suggested requirements might well serve as a standard but do not prescribe a single manner in which all devices should be evaluated. They instead motivate such an evaluation and describe how examinations might be performed. It is understood that methods will change and knowledge will evolve, in particular as corroboration is established with clinical data. The dynamic nature of this document allows for future modifications and additions. A drug-eluting stent presents or releases single or multiple bioactive agents into the blood stream. The drug can deposit in and/or affect blood vessels, cells, plaque, or tissues either adjacent to the stent or at a distance. Systemic drug concentrations may be avoided or desirable. It is assumed that drugs undergoing preclinical evaluation will have sound theoretical and practical reasons for biological success, and that the preclinical studies will help answer the magnitude and safety of effect when presented with or from the stent. It is likely that substantial empirical data already exists documenting the effects of these drugs on isolated cells in culture and even in vivo after systemic administration. Some drugs may already be in clinical use. Drug can be embedded and released from within (“matrix-type”) or surrounded by and released through (“reservoir-type”) polymer materials that coat …

Automatic External Defibrillators for Public Access Defibrillation: Recommendations for Specifying and Reporting Arrhythmia Analysis Algorithm Performance, Incorporating New Waveforms, and Enhancing Safety A Statement for Health Professionals From the American Heart Association Task Force on Automatic External Defibrillation, Subcommittee on AED Safety and Efficacy

These recommendations are presented to enhance the safety and efficacy of AEDs intended for public access. The task force recommends that manufacturers present developmental and validation data on their own devices, emphasizing high sensitivity for shockable rhythms and high specificity for nonshockable rhythms. Alternative defibrillation waveforms may reduce energy requirements, reducing the size and weight of the device. The highest levels of safety for public access defibrillation are needed. Safe and effective use of AEDs that are widely available and easily handled by nonmedical personnel has the potential to dramatically increase survival from cardiac arrest.

Preclinical Evaluation of Drug-Eluting Stents for Peripheral Applications Recommendations From an Expert Consensus Group

Drug-eluting stents implanted in the coronary arteries substantially improve long-term outcomes for restenosis. The utility of the stents in peripheral atherosclerosis is under evaluation. Drug-eluting stent evaluation with coronary arteries appears to be an excellent method for evaluating human safety end points. Predicting clinical efficacy remains unclear, however. Because drug-eluting stents are undergoing development for human peripheral arteries, safety and efficacy questions arise in much the same context as they did for the coronary arteries. As they did with the coronary arteries, the clinical, scientific, regulatory, and commercial communities are seeking acceptable criteria for peripheral device evaluation. Substantial differences in stent requirements and biological effects for bare metal peripheral stents depend on implant site. Different anatomic locations under evaluation include femoral, renal, and neurologic arterial stents, and other peripheral applications such as outflow veins of dialysis arteriovenous fistulae are being evaluated. Peripheral in-stent restenosis is less of a problem in carotid and aortoiliac stents and in iliac veins and in the cavae. In general, the benefit:risk ratio for drug-eluting stents may be less for peripheral stents. It is for this reason that peripheral stent performance should be evaluated carefully. This document presents an integrated recommendation set for evaluating drug-eluting stents in peripheral vessels with preclinical models. The recommendations encompass study design, experimental performance, and histopathologic evaluations and emphasize the need to evaluate safety and efficacy at multiple points in time. The present document is a consensus of clinical, academic, and commercial groups—all experts in the evaluation of preclinical investigational or interventional devices. Because preclinical peripheral studies are less well understood than are coronary models, the recommendations do not prescribe a single method for device evaluation; they instead provide broad suggestions for evaluation. Peripheral vascular knowledge will increase as correlations of preclinical with clinical data become available. Future versions of this …

Transcatheter valve therapy registry is a model for medical device innovation and surveillance.

Heart valve diseases are increasingly prevalent, especially in people older than age seventy. Many of these elderly people have other comorbid conditions, making them poor candidates for surgical treatment of heart valve diseases. Since 2011 such patients have been eligible to receive new nonsurgical heart valve treatments approved by the Food and Drug Administration (FDA) and covered by Medicare. This article examines the Transcatheter Valve Therapy Registry, which captures clinical information on all US patients undergoing new nonsurgical heart valve treatments. The registry has patient-level data from more than 27,000 patients treated with the novel devices. Patient- and procedure-related data are gathered from hospitals, patient-reported outcomes are assessed pre- and postprocedure, and longer-term data on mortality and repeat hospitalization are provided by linking the registrys data to Medicare patient data. The registry is a model of collaboration among professional societies, the FDA, the Centers for Medicare and Medicaid Services, hospitals, patients, and the medical device industry. It has been used to support Medicare coverage decisions, expand device indications, provide comprehensive device surveillance, and establish national quality benchmarks. Beyond having it serve as a collaborative model, future goals for the registry include shortening the FDA-approval timeline for devices, providing data for decision-making tools for patients, and public reporting of hospital performance.

FDA perspective on objective performance goals and clinical trial design for evaluating catheter-based treatment of critical limb ischemia.

The article by Conte et al.(1) on behalf of the Society for Vascular Surgery (SVS) in this issue of the Journal of Vascular Surgery provides guidelines for improving the consistency and interpretability of clinical trials intended to evaluate treatment options for patients with critical limb ischemia (CLI). This article identifies a number of key challenges with conducting and comparing CLI trials, including the wide spectrum of clinical presentations that CLI encompasses, the use of disparate eligibility criteria and endpoint measurements, and logistical and economic considerations that can limit study initiation and completion. The authors propose definitions for a number of performance goals derived from historical surgical literature as a means of reducing the negative impact of these factors. The current editorial reviews aspects of this proposal from the perspective of the authors in terms of their understanding of the statutory obligations of the U.S. Food and Drug Administration (FDA) to regulate the marketing of cardiovascular devices based on valid scientific evidence.

An analysis of implantable cardiac device reliability. The case for improved postmarketing risk assessment and surveillance.

Implantable cardiac devices have become the mainstay of the treatment of patients with heart disease. However, data regarding their reliability and, inferentially, safety have been called into question. We reviewed annual reports submitted to the Food and Drug Administration Office of Device Evaluation by device manufacturers from 2003 to 2007. The annual number of implantable cardiac defibrillators (ICDs) and cardiac resynchronization therapy defibrillator (CRT-D) implants, explants, and returned devices were tabulated along with the cumulative (Cum) number of implants for each device. We derived an annual explantation rate (AER) defined as the ratio of the annual number of explants less the number of normal battery depletions/Cum (×1000). From 2003 to 2007, 256,392 CRT-D and 459,300 ICD devices were implanted in the United States. The overall mean (±SD) AERs for ICD and CRT-D devices were, respectively, 49.5 (15.6) per 1000 ICD devices and 82.6 (35.5) per 1000 CRT-D devices. The AER for each device type significantly decreased over the study period (P for trend <0.001) although the AER for CRT-D devices was 38% higher than that for ICD devices (P < 0.001). On average, 20.3% of CRT-D devices and 22.6% of ICD devices were returned to the manufacturer for analysis after explantation. The rates of explanted CRT-D and ICD devices decreased from 2003 to 2007. Notwithstanding this favorable trend, the AER for CRT-D devices was higher than that for ICD devices. Improved methods for tracking individual device histories are needed for more precise estimates of the risk of device explantation for suspected malfunction. The proportion of devices returned to the manufacturer is suboptimal and needs to be improved to better understand the mechanisms of device malfunction.

Patent Foramen Ovale after Cryptogenic Stroke — Assessing the Evidence for Closure

The benefit of closing a patent foramen ovale after a cryptogenic stroke has been an open question. The FDA recently approved the Amplatzer PFO Occluder in light of a nonsignificant reduction in recurrent ischemic stroke with the device and a favorable safety profile.

Vascular effects of diet-induced hypercalcemia after balloon artery injury in giant Flemish rabbits

To determine whether metastatic calcification during neointima formation can result in neointimal calcification that simulates advanced human atherosclerosis, 32 giant Flemish rabbits (weight 5.5 +/- 0.6 kg) underwent overstretch balloon injury of bilateral iliac arteries and received diet therapy for 8 weeks: high cholesterol (2%) and low calcium-vitamin D2 regimen (250 mg of calcium carbonate orally 5 times weekly and 50,000 U of calciferol intramuscularly 3 times weekly; group 1; n = 5); low cholesterol (0.5%) and high calcium-vitamin D2 regimen (500 mg of calcium carbonate orally 5 times weekly and 100,000 U of calciferol intramuscularly three times weekly; group 2; n = 19); or 0% cholesterol and high calcium-vitamin D2 regimen (group 3; n = 8). The incidence of vascular calcification was highest (71.4%) in group 2. Eighty-one percent of calcification was medial. Residual strain measurements of 7 thoracic aortas from group 2 compared to normal thoracic aortas from 8 control rabbits showed that residual strain was significantly increased in the calcified atherosclerotic aortas (12.3% vs 5.2%; p = 0.001). We conclude that diet-induced hypercalcemia predominantly affects the media despite the presence of concomitant neointima formation from balloon artery injury with or without hypercholesterolemia and increases the residual strain more than twofold compared to normal thoracic aortas.

FDA perspective on clinical trial design for femoropopliteal stent correction of peripheral vascular insufficiency cardiovascular devices.

The article by Rocha-Singh et al. [1]. on behalf of the VIVA Physicians Incorporate (VPI) in this issue of the Catheterization and Cardiac Interventions addresses the challenge to designing clinical trials for devices intended to correct femoropopliteal arterial insufficiency. As discussed in this article, the polymorphic pathology of this disease process accounts for a broad spectrum of clinical presentations that confounds the ability to design and execute a conventional controlled clinical trial. The authors suggest that this problem may be addressed by devising performance goals based on historical data that will allow study of a particular technological advance, use of mechanical stenting in treatment of peripheral arterial disease (PAD), by means of logistically feasible observational studies. This editorial reviews aspects of this proposal from the perspective of the authors in terms of their understanding of the statutory obligations of the Food and Drug Administration (FDA) to regulate the marketing of cardiovascular implants based on valid scientific evidence.