EDTA treatment of intermittent claudication--a double-blind, placebo-controlled study

Effect of EDTA with porous balloon on calcified lesion: An atherosclerotic cadaver study

BACKGROUND

Ethylene diamine tetra-acetic acid (EDTA) is a chelating agent used to dissolve calcium deposits but evidence in decalcifying atherosclerotic lesions is limited.

AIMS

We assessed the feasibility and efficacy of EDTA delivered via porous balloon to target calcified lesions in cadaveric below-the-knee (BTK) arteries.

METHODS

Using porcine carotid arteries, EDTA concentration was measured in the arterial wall and outside the artery at the 0-, 0.5-, 4-, and 24-h circulation after the injection through a porous balloon. In cadaver BTK samples, the proximal and distal anterior tibial artery (ATA) and distal posterior tibial artery (PTA) were studied. EDTA-2Na/H2O or EDTA-3Na/H2O were administrated using a porous balloon, then circulated for 6 h for EDTA-3Na/H2O and 24 h for EDTA-2Na/H2O and EDTA-3Na/H2O. Micro-CT imaging of the artery segments before and after the circulation and cross-sectional analyses were performed to evaluate calcium burden.

RESULTS

In the porcine carotid study, EDTA was delivered through a porous balloon present in the arterial wall and was retained there for 24 h. In BTK arteries, cross-sectional analyses of micro-CT revealed a significant decrease in the calcium area in the distal ATA segment under 24-h circulation with EDTA-2Na/H2O and in the distal ATA segment under 24-h circulation with EDTA-3Na/H2O. The proximal ATA segment under 6-h circulation with EDTA-3Na/H2O showed no significant change in any parameters of calcium CONCLUSION: EDTA-3Na/H2O or EDTA-2Na/H2O with longer circulation times resulted in greater calcium reduction in atherosclerotic lesion. EDTA may have a potential therapeutic option for the treatment of atherosclerotic calcified lesions.

Vitamin K and Calcium Chelation in Vascular Health

The observation that the extent of artery calcification correlates with the degree of atherosclerosis was the background for the alternative treatment of cardiovascular disease with chelator ethylenediamine tetraacetate (EDTA). Recent studies have indicated that such chelation treatment has only marginal impact on the course of vascular disease. In contrast, endogenous calcium chelation with removal of calcium from the cardiovascular system paralleled by improved bone mineralization exerted, i.e., by matrix Gla protein (MGP) and osteocalcin, appears to significantly delay the development of cardiovascular diseases. After post-translational vitamin-K-dependent carboxylation of glutamic acid residues, MGP and other vitamin-K-dependent proteins (VKDPs) can chelate calcium through vicinal carboxyl groups. Dietary vitamin K is mainly provided in the form of phylloquinone from green leafy vegetables and as menaquinones from fermented foods. Here, we provide a review of clinical studies, addressing the role of vitamin K in cardiovascular diseases, and an overview of vitamin K kinetics and biological actions, including vitamin-K-dependent carboxylation and calcium chelation, as compared with the action of the exogenous (therapeutic) chelator EDTA. Consumption of vitamin-K-rich foods and/or use of vitamin K supplements appear to be a better preventive strategy than EDTA chelation for maintaining vascular health.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease."

METHODS

A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease" provides an update to and consolidates new evidence since the "2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease" and the corresponding "2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease."

METHODS

A comprehensive literature search was conducted from September 2021 to May 2022. Clinical studies, systematic reviews and meta-analyses, and other evidence conducted on human participants were identified that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

This guideline provides an evidenced-based and patient-centered approach to management of patients with chronic coronary disease, considering social determinants of health and incorporating the principles of shared decision-making and team-based care. Relevant topics include general approaches to treatment decisions, guideline-directed management and therapy to reduce symptoms and future cardiovascular events, decision-making pertaining to revascularization in patients with chronic coronary disease, recommendations for management in special populations, patient follow-up and monitoring, evidence gaps, and areas in need of future research. Where applicable, and based on availability of cost-effectiveness data, cost-value recommendations are also provided for clinicians. Many recommendations from previously published guidelines have been updated with new evidence, and new recommendations have been created when supported by published data.

Chelation Therapy in Patients With Cardiovascular Disease: A Systematic Review

Background EDTA is an intravenous chelating agent with high affinity to divalent cations (lead, cadmium, and calcium) that may be beneficial in the treatment of cardiovascular disease (CVD). Although a large randomized clinical trial showed benefit, smaller studies were inconsistent. We conducted a systematic review of published studies to examine the effect of repeated EDTA on clinical outcomes in adults with CVD. Methods and Results We searched 3 databases (MEDLINE, Embase, and Cochrane) from database inception to October 2021 to identify all studies involving EDTA treatment in patients with CVD. Predetermined outcomes included mortality, disease severity, plasma biomarkers of disease chronicity, and quality of life. Twenty-four studies (4 randomized clinical trials, 15 prospective before/after studies, and 5 retrospective case series) assessed the use of repeated EDTA chelation treatment in patients with preexistent CVD. Of these, 17 studies (1 randomized clinical trial) found improvement in their respective outcomes following EDTA treatment. The largest improvements were observed in studies with high prevalence of participants with diabetes and/or severe occlusive arterial disease. A meta-analysis conducted with 4 studies reporting ankle-brachial index indicated an improvement of 0.08 (95% CI, 0.06-0.09) from baseline. Conclusions Overall, 17 studies suggested improved outcomes, 5 reported no statistically significant effect of treatment, and 2 reported no qualitative benefit. Repeated EDTA for CVD treatment may provide more benefit to patients with diabetes and severe peripheral arterial disease. Differences across infusion regimens, including dosage, solution components, and number of infusions, limit comparisons across studies. Additional research is necessary to confirm these findings and to evaluate the potential mediating role of metals. Registration URL: https://www.crd.york.ac.uk/; Unique identifier: CRD42020166505.

Heavy Metal Toxicity in Chronic Renal Failure and Cardiovascular Disease: Possible Role for Chelation Therapy

Exposure to heavy metals is common. This exposure is related to environmental contamination of air, water and soil, occupational exposure, accumulation in food, tobacco, and other factors. Cadmium and lead are notable for their widespread contamination, long-lasting effects in the body, and renal as well as cardiovascular toxicity. Acute toxicity due to high-level exposure, as well as chronic low-level exposure are now well-established pathogenic entities. Both chronic renal failure and ischemic heart disease patients have been treated separately in recent studies with ethylenediaminetetraacetic acid (EDTA) chelation therapy. In patients with chronic kidney disease (serum creatinine: 1.5-4.0 mg/dL) and increased body lead burden, weekly low-dose chelation with calcium EDTA slowed the rate of decline in renal function in patients with diabetes and in non-diabetic patients. In patients with a history of myocardial infarction, the Trial to Assess Chelation Therapy study showed that EDTA chelation decreased the likelihood of cardiovascular events, particularly in patients with diabetes. However, heavy metal levels were not measured in this study. It is clear that more research is needed in this area. There is also a need to more frequently consider and test for the possibility of cadmium and lead toxicity in patients with increased risk, such as those with hypertension, diabetes mellitus, and chronic renal disease.

Low-Level Cadmium Exposure and Atherosclerosis

PURPOSE OF REVIEW

Cadmium has been recognized as a potential risk factor for cardiovascular disease (CVD). We present a review of cadmium toxicity, its effect on cellular activities, and a summary of reported association between environmental cadmium exposure and CVD. We also discuss the possible therapeutic benefit of cadmium chelation.

RECENT FINDINGS

Experimental data suggest that cadmium affects several signaling pathways which may lead to endothelial dysfunction and vascular tissue damage, promoting atherosclerosis. This is further supported by epidemiological studies that have shown an association of even low-level cadmium exposure with an increased risk of clinical cardiovascular events. The Trial to Assess Chelation Therapy (TACT) provided inferential evidence for the cardiovascular benefit of treating toxic metal burden. However, at the present time, there is no direct evidence, but suggestive findings from clinical trials indicating that removal of cadmium from body stores may be associated with improved cardiovascular outcomes. An evolving body of evidence supports environmental cadmium exposure as a pro-atherosclerosis risk factor in CVD; however, the mechanisms for the proatherogenic effect of cadmium are still not completely understood. Further studies in translational toxicology are needed to fill the knowledge gaps regarding the molecular mechanisms of cadmium toxicity and the promotion of atherosclerosis.

Chelation therapy for atherosclerotic cardiovascular disease

BACKGROUND

Chelation therapy is promoted and practiced around the world as a form of alternative medicine in the treatment of atherosclerotic cardiovascular disease. It has been suggested as a safe, relatively inexpensive, non-surgical method of restoring blood flow in atherosclerotic vessels. However, there is currently limited high-quality, adequately-powered research informing evidence-based medicine on the topic, specifically regarding clinical outcomes. Due to this limited evidence, the benefit of chelation therapy remains controversial at present. This is an update of a review first published in 2002.

OBJECTIVES

To assess the effects of ethylene diamine tetra-acetic acid (EDTA) chelation therapy versus placebo or no treatment on clinical outcomes among people with atherosclerotic cardiovascular disease.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases, the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials register to 6 August 2019. We searched the bibliographies of the studies retrieved by the literature searches for further trials.

SELECTION CRITERIA

We included studies if they were randomised controlled trials of EDTA chelation therapy versus placebo or no treatment in participants with atherosclerotic cardiovascular disease. The main outcome measures we considered include all-cause or cause-specific mortality, non-fatal cardiovascular events, direct or indirect measurement of disease severity, and subjective measures of improvement or adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality using standard Cochrane procedures. A third author considered any unresolved issues, and we discussed any discrepancies until a consensus was reached. We contacted study authors for additional information.

MAIN RESULTS

We included five studies with a total of 1993 randomised participants. Three studies enrolled participants with peripheral vascular disease and two studies included participants with coronary artery disease, one of which specifically recruited people who had had a myocardial infarction. The number of participants in each study varied widely (from 10 to 1708 participants), but all studies compared EDTA chelation to a placebo. Risk of bias for the included studies was generally moderate to low, but one study had high risk of bias because the study investigators broke their randomisation code halfway through the study and rolled the placebo participants over to active treatment. Certainty of the evidence, as assessed by GRADE, was generally low to very low, which was mostly due to a paucity of data in each outcome's meta-analysis. This limited our ability to draw any strong conclusions. We also had concerns about one study's risk of bias regarding blinding and outcome assessment that may have biased the results. Two studies with coronary artery disease participants reported no evidence of a difference in all-cause mortality between chelation therapy and placebo (risk ratio (RR) 0.97, 95% CI 0.73 to 1.28; 1792 participants; low-certainty). One study with coronary artery disease participants reported no evidence of a difference in coronary heart disease deaths between chelation therapy and placebo (RR 1.02, 95% CI 0.70 to 1.48; 1708 participants; very low-certainty). Two studies with coronary artery disease participants reported no evidence of a difference in myocardial infarction (RR 0.81, 95% CI 0.57 to 1.14; 1792 participants; moderate-certainty), angina (RR 0.95, 95% CI 0.55 to 1.67; 1792 participants; very low-certainty), and coronary revascularisation (RR 0.46, 95% CI 0.07 to 3.25; 1792 participants). Two studies (one with coronary artery disease participants and one with peripheral vascular disease participants) reported no evidence of a difference in stroke (RR 0.88, 95% CI 0.40 to 1.92; 1867 participants; low-certainty). Ankle-brachial pressure index (ABPI; also known as ankle brachial index) was measured in three studies, all including participants with peripheral vascular disease; two studies found no evidence of a difference in the treatment groups after three months after treatment (mean difference (MD) 0.02, 95% CI -0.03 to 0.06; 181 participants; low-certainty). A third study reported an improvement in ABPI in the EDTA chelation group, but this study was at high risk of bias. Meta-analysis of maximum and pain-free walking distances three months after treatment included participants with peripheral vascular disease and showed no evidence of a difference between the treatment groups (MD -31.46, 95% CI -87.63 to 24.71; 165 participants; 2 studies; low-certainty). Quality of life outcomes were reported by two studies that included participants with coronary artery disease, but we were unable to pool the data due to different methods of reporting and varied criteria. However, there did not appear to be any major differences between the treatment groups. None of the included studies reported on vascular deaths. Overall, there was no evidence of major or minor adverse events associated with EDTA chelation treatment.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to determine the effectiveness or ineffectiveness of chelation therapy in improving clinical outcomes of people with atherosclerotic cardiovascular disease. More high-quality, randomised controlled trials are needed that assess the effects of chelation therapy on longevity and quality of life among people with atherosclerotic cardiovascular disease.

Potential Role of Metal Chelation to Prevent the Cardiovascular Complications of Diabetes

CONTEXT

For decades, there has been epidemiologic evidence linking chronic toxic metal exposure with cardiovascular disease, suggesting a therapeutic role for metal chelation. Given the lack of compelling scientific evidence, however, the indications for metal chelation were never clearly defined. To determine the safety and efficacy of chelation therapy, the National Institutes of Health funded the Trial to Assess Chelation Therapy (TACT). TACT was the first double-blind, randomized, controlled trial to demonstrate an improvement in cardiovascular outcomes with edetate disodium therapy in patients with prior myocardial infarction. The therapeutic benefit was striking among the prespecified subgroup of patients with diabetes.

DESIGN

We review the published literature focusing on the atherogenic nature of diabetes, as well as available evidence from clinical trials, complete and in progress, of metal chelation with edetate disodium therapy in patients with diabetes.

RESULTS

The TACT results support the concept that ubiquitous toxic metals such as lead and cadmium may be modifiable risk factors for cardiovascular disease, particularly in patients with diabetes.

CONCLUSIONS

The purpose of this review is to discuss the potential mechanisms unifying the pathogenesis of atherogenic factors in diabetes with toxic metal exposure, and the potential role of metal chelation.

Multiple Non-Essential Transition Metals Are Accumulated in Carotid Atherosclerotic Plaques: Missing Link in Atherosclerosis?

Population studies revealed that metal exposure through food, environment, and smoking was related with increased risk of cardiovascular disease. In this study, we determined complex chemical elements in surgical carotid endarterectomy specimens and carotid tissues from autopsies without atherosclerosis. Atherosclerotic plaques from 41 endarterectomies and normal carotid tissue from 30 autopsies were collected and elemental composition was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) method. Eleven (26.8%) patients never smoked in carotid endarterectomy group. One patient was brass souvenir worker and one was goldsmith and others did not have direct contact with metals in the carotid endarterectomy group. Na, Cu, Mn, Bi, Co, Mo, Ni, Pb, Sb, Se, Sn, Ti, and W levels were not different between two groups. Bi, Co, Mo, Pb, Ti, and W were below the detection limit of ICP-OES in both groups. Concentrations of Mg, K, Ca, P, Fe, B, Zn, Al, As, Cr, Pt, and Hg were significantly higher in carotid endarterectomies than normal carotid tissue samples. Cd and S values were significantly higher in autopsy samples. There is significant multiple non-essential transition metal accumulation in atherosclerotic carotid endarterectomy plaques. The cardiovascular consequences of metal toxicity have not been researched adequately due to large emphasis on the role of cholesterol in atherosclerosis. High level of non-essential transition metal elements in the carotid atherosclerotic plaques may add the missing link of atherogenesis and may necessitate new treatment and prevention strategies in carotid disease if confirmed by further research.

Chelation therapy to prevent diabetes-associated cardiovascular events

PURPOSE OF REVIEW

For over 60 years, chelation therapy with disodium ethylene diamine tetraacetic acid (EDTA, edetate) had been used for the treatment of cardiovascular disease (CVD) despite lack of scientific evidence for efficacy and safety. The Trial to Assess Chelation Therapy (TACT) was developed and received funding from the National Institutes of Health (NIH) to ascertain the safety and efficacy of chelation therapy in patients with CVD.

RECENT FINDINGS

This pivotal trial demonstrated an improvement in outcomes in postmyocardial infarction (MI) patients. Interestingly, it also showed a particularly large reduction in CVD events and all-cause mortality in the prespecified subgroup of patients with diabetes. The TACT results may support the concept of metal chelation to reduce metal-catalyzed oxidation reactions that promote the formation of advanced glycation end products, a precursor of diabetic atherosclerosis.

SUMMARY

In this review, we summarize the epidemiological and basic evidence linking toxic metal accumulation and diabetes-related CVD, supported by the salutary effects of chelation in TACT. If the ongoing NIH-funded TACT2, in diabetic post-MI patients, proves positive, this unique therapy will enter the armamentarium of endocrinologists and cardiologists seeking to reduce the atherosclerotic risk of their diabetic patients.

Chronic Toxic Metal Exposure and Cardiovascular Disease: Mechanisms of Risk and Emerging Role of Chelation Therapy

Over the last few decades, there has been a growing body of epidemiologic evidence linking chronic toxic metal exposure to cardiovascular disease-related morbidity and mortality. The recent and unexpectedly positive findings from a randomized, double-blind, multicenter trial of metal chelation for the secondary prevention of atherosclerotic cardiovascular disease (Trial to Assess Chelation Therapy (TACT)) have focused the discussion on the role of chronic exposure to toxic metals in the development and propagation of cardiovascular disease and the role of toxic metal chelation therapy in the secondary prevention of cardiovascular disease. This review summarizes the most recent evidence linking chronic toxic metal exposure to cardiovascular disease and examines the findings of TACT.

Edetate Disodium-Based Treatment for Secondary Prevention in Post-Myocardial Infarction Patients

An abundance of data, known for decades, is available linking metals, such as lead and cadmium, with cardiovascular disease. However, the idea that these toxic metals could be a modifiable risk factor for atherosclerosis did not become apparent clinically until the completion of the Trial to Assess Chelation Therapy in 2012. This pivotal study was the first double-blind, randomized, controlled trial of its kind to demonstrate a clear improvement in cardiovascular outcomes with edetate disodium therapy in a secondary prevention, post-myocardial infarction population. This effect size was most striking in diabetic patients, where the efficacy of edetate disodium was comparable, if not superior, to that of current guideline-based therapies. Given the economic burden of diabetes and cardiovascular disease, the potential impact of this therapy could be enormous if the results of this study are replicated.

Chelation therapy to treat atherosclerosis, particularly in diabetes: is it time to reconsider?

INTRODUCTION

Case reports and case series have suggested a possible beneficial effect of chelation therapy in patients with atherosclerotic disease. Small randomized trials conducted in patients with angina or peripheral artery disease, however, were not sufficiently powered to provide conclusive evidence on clinical outcomes.

AREAS COVERED

The Trial to Assess Chelation Therapy (TACT) was the first randomized trial adequately powered to detect the effects of chelation therapy on clinical endpoints. We discuss results and future research. Expert commentary: Chelation reduced adverse cardiovascular events in a post myocardial infarction (MI) population. Patients with diabetes demonstrated even greater benefit, with a number needed to treat of 6.5 patients to prevent a cardiac event over 5 years, with a 41% relative reduction in risk of a cardiac event (p = 0.0002). These results led to the revision of the ACC/AHA guideline recommendations for chelation therapy, changing its classification from class III to class IIb. TACT2, a replicative trial, will assess the effects of chelation therapy on cardiovascular outcomes in diabetic patients with a prior myocardial infarction. We are seeking participating sites for TACT2.

Heavy Metals, Cardiovascular Disease, and the Unexpected Benefits of Chelation Therapy

This review summarizes evidence from 2 lines of research previously thought to be unrelated: the unexpectedly positive results of TACT (Trial to Assess Chelation Therapy), and a body of epidemiological data showing that accumulation of biologically active metals, such as lead and cadmium, is an important risk factor for cardiovascular disease. Considering these 2 areas of work together may lead to the identification of new, modifiable risk factors for atherosclerotic cardiovascular disease. We examine the history of chelation up through the report of TACT. We then describe work connecting higher metal levels in the body with the future risk of cardiovascular disease. We conclude by presenting a brief overview of a newly planned National Institutes of Health trial, TACT2, in which we will attempt to replicate the findings of TACT and to establish that removal of toxic metal stores from the body is a plausible mechanistic explanation for the benefits of edetate disodium treatment.

Quality-of-life outcomes with a disodium EDTA chelation regimen for coronary disease: results from the trial to assess chelation therapy randomized trial

BACKGROUND

The National Institutes of Health.funded Trial to Assess Chelation Therapy (TACT) randomized 1708 stablecoronary disease patients aged .50 years who were .6 months post.myocardial infarction (2003.2010) to 40 infusions ofa multicomponent EDTA chelation solution or placebo. Chelation reduced the primary composite end point of mortality,recurrent myocardial infarction, stroke, coronary revascularization, or hospitalization for angina (hazard ratio, 0.82; 95%confidence interval, 0.69.0.99; P=0.035).

METHODS AND RESULTS

In a randomly selected subset of 911 patients, we prospectively collected a battery of quality-of-life(QOL) instruments at baseline and at 6, 12, and 24 months after randomization. The prespecified primary QOL measures were the Duke Activity Status Index (Table I in the Data Supplement) and the Medical Outcomes Study Short-Form 36 Mental Health Inventory-5. All comparisons were by intention to treat. Baseline clinical and QOL variables were well balanced in the 451 patients randomized to chelation and in the 460 patients randomized to placebo. The Duke Activity Status Index improved in both groups during the first 6 months of therapy, but we found no evidence for a treatment-related difference (mean difference [chelation.placebo] during follow-up, 0.9 [95% confidence interval, .0.7 to 2.6; P=0.27]).There was no statistically significant evidence of a treatment-related difference in the Mental Health Inventory-5 during follow-up (mean difference, 1.0; 95% confidence interval, .0.1 to 2.0; P=0.08). None of the secondary QOL measures showed a consistent treatment-related difference.

CONCLUSIONS

In stable, predominantly asymptomatic coronary disease patients with a history of myocardial infarction,EDTA chelation therapy did not have a detectable effect on QOL during 2 years of follow-up.

CLINICAL TRIAL REGISTRATION

URL: http://clinicaltrials.gov. Unique identifier: NCT00044213.

Chelation therapy after the trial to assess chelation therapy: results of a unique trial

PURPOSE OF REVIEW

EDTA chelation therapy has been in off-label use for the treatment of atherosclerosis. We review the results of the first large-scale randomized trial of this treatment.

RECENT FINDINGS

The trial to assess chelation therapy was a $30 million National Institutes of Health-funded study of the safety and efficacy of EDTA-based chelation infusions in 1708 post-myocardial infarction (MI) patients. The trial to assess chelation therapy demonstrated a significant (P=0.035) 18% reduction in a combined primary endpoint of death, MI, stroke, coronary revascularization, or hospitalization for angina. In diabetic patients the benefit was more extreme, with a 41% relative reduction in risk (P=0.0002) and a 43% reduction in total mortality (P=0.011). Safety data were favorable. A reduction of oxidative stress by chelation of toxic metals has been proposed as a possible mechanism of action.

SUMMARY

Recent research suggests that EDTA chelation may be a well-tolerated and effective treatment for post-MI patients. Future replication and mechanistic studies are important prior to implementation in all post-MI patients.

Chelation therapy and cardiovascular disease: connecting scientific silos to benefit cardiac patients

Medical practitioners have treated atherosclerotic disease with chelation therapy for over 50 years. Lack of strong of evidence led conventional practitioners to abandon its use in the 1960s and 1970s. This relegated chelation therapy to complementary and alternative medicine practitioners, who reported good anecdotal results. Concurrently, the epidemiologic evidence linking xenobiotic metals with cardiovascular disease and mortality gradually accumulated, suggesting a plausible role for chelation therapy. On the basis of the continued use of chelation therapy without an evidence base, the National Institutes of Health released a Request for Applications for a definitive trial of chelation therapy. The Trial to Assess Chelation Therapy (TACT) was formulated as a 2 × 2 factorial randomized controlled trial of intravenous EDTA-based chelation vs. placebo and high-dose oral multivitamins and multiminerals vs. oral placebo. The composite primary endpoint was death, reinfarction, stroke, coronary revascularization, or hospitalization for angina. A total of 1708 post-MI patients who were 50 years or older with a creatinine of 2.0 or less were enrolled and received 55,222 infusions of disodium EDTA or placebo with a median follow-up of 55 months. Patients were on evidence-based post-MI medications including statins. EDTA proved to be safe. EDTA chelation therapy reduced cardiovascular events by 18%, with a 5-year number needed to treat (NNT) of 18. Prespecified subgroup analysis revealed a robust benefit in patients with diabetes mellitus with a 41% reduction in the primary endpoint (5-year NNT = 6.5), and a 43% 5-year relative risk reduction in all-cause mortality (5-year NNT = 12). The magnitude of benefit is such that it suggests urgency in replication and implementation, which could, due to the excellent safety record, occur simultaneously.

Effect of disodium EDTA chelation regimen on cardiovascular events in patients with previous myocardial infarction: the TACT randomized trial

IMPORTANCE

Chelation therapy with disodium EDTA has been used for more than 50 years to treat atherosclerosis without proof of efficacy.

OBJECTIVE

To determine if an EDTA-based chelation regimen reduces cardiovascular events.

DESIGN, SETTING, AND PARTICIPANTS

Double-blind, placebo-controlled, 2 × 2 factorial randomized trial enrolling 1708 patients aged 50 years or older who had experienced a myocardial infarction (MI) at least 6 weeks prior and had serum creatinine levels of 2.0 mg/dL or less. Participants were recruited at 134 US and Canadian sites. Enrollment began in September 2003 and follow-up took place until October 2011 (median, 55 months). Two hundred eighty-nine patients (17% of total; n=115 in the EDTA group and n=174 in the placebo group) withdrew consent during the trial.

INTERVENTIONS

Patients were randomized to receive 40 infusions of a 500-mL chelation solution (3 g of disodium EDTA, 7 g of ascorbate, B vitamins, electrolytes, procaine, and heparin) (n=839) vs placebo (n=869) and an oral vitamin-mineral regimen vs an oral placebo. Infusions were administered weekly for 30 weeks, followed by 10 infusions 2 to 8 weeks apart. Fifteen percent discontinued infusions (n=38 [16%] in the chelation group and n=41 [15%] in the placebo group) because of adverse events.

MAIN OUTCOME MEASURES

The prespecified primary end point was a composite of total mortality, recurrent MI, stroke, coronary revascularization, or hospitalization for angina. This report describes the intention-to-treat comparison of EDTA chelation vs placebo. To account for multiple interim analyses, the significance threshold required at the final analysis was P = .036.

RESULTS

Qualifying previous MIs occurred a median of 4.6 years before enrollment. Median age was 65 years, 18% were female, 9% were nonwhite, and 31% were diabetic. The primary end point occurred in 222 (26%) of the chelation group and 261 (30%) of the placebo group (hazard ratio [HR], 0.82 [95% CI, 0.69-0.99]; P = .035). There was no effect on total mortality (chelation: 87 deaths [10%]; placebo, 93 deaths [11%]; HR, 0.93 [95% CI, 0.70-1.25]; P = .64), but the study was not powered for this comparison. The effect of EDTA chelation on the components of the primary end point other than death was of similar magnitude as its overall effect (MI: chelation, 6%; placebo, 8%; HR, 0.77 [95% CI, 0.54-1.11]; stroke: chelation, 1.2%; placebo, 1.5%; HR, 0.77 [95% CI, 0.34-1.76]; coronary revascularization: chelation, 15%; placebo, 18%; HR, 0.81 [95% CI, 0.64-1.02]; hospitalization for angina: chelation, 1.6%; placebo, 2.1%; HR, 0.72 [95% CI, 0.35-1.47]). Sensitivity analyses examining the effect of patient dropout and treatment adherence did not alter the results.

CONCLUSIONS AND RELEVANCE

Among stable patients with a history of MI, use of an intravenous chelation regimen with disodium EDTA, compared with placebo, modestly reduced the risk of adverse cardiovascular outcomes, many of which were revascularization procedures. These results provide evidence to guide further research but are not sufficient to support the routine use of chelation therapy for treatment of patients who have had an MI.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00044213.

Design of the Trial to Assess Chelation Therapy (TACT)

TACT is an National Institutes of Health-sponsored, randomized, double-blind, placebo-controlled, 2 × 2 factorial clinical trial testing the benefits and risks of 40 infusions of a multicomponent disodium EDTA chelation solution compared with placebo and of an oral, high-dose multivitamin and mineral supplement. TACT has randomized and will follow up 1,708 patients for an average of approximately 4 years. The primary end point is a composite of all-cause mortality, myocardial infarction, stroke, coronary revascularization, and hospitalization for angina. A 900-patient substudy will examine quality-of-life outcomes. The trial is designed to have >85% power to detect a 25% relative reduction in the primary end point for each treatment factor. Enrollment began in September 2003 and was completed in October 2010.

Challenges associated with metal chelation therapy in Alzheimer's disease

A close association between brain metal dishomeostasis and the onset and/or progression of Alzheimer's disease (AD) has been clearly established in a number of studies, although the underlying biochemical mechanisms remain obscure. This observation renders chelation therapy an attractive pharmacological option for the treatment of this disease. However, a number of requirements must be fulfilled in order to adapt chelation therapy to AD so that the term "metal targeted strategies" seems now more appropriate. Indeed, brain metal redistribution rather than brain metal scavenging and removal is the major goal of this type of intervention. The most recent developments in metal targeted strategies for AD will be discussed using, as useful examples, clioquinol, curcumin, and epigallocatechin, and the future perspectives will also be outlined.

Treatment strategies for peripheral artery disease

Peripheral arterial disease is an underecognized manifestation of systemic atherosclerosis associated with high rates of cardiovascular morbidity and mortality. The rationale of therapy is to reduce cardiovascular risk, improve symptoms of intermittent claudication, and prevent the development of critical limb ischemia and amputation. Exercise therapy and several pharmacologic agents have been shown to improve walking distance in patients with intermittent claudication. Patients with lifestyle-interfering symptoms despite exercise, or those who progress to critical limb ischemia, frequently undergo revascularization. Endovascular techniques are commonly used in these patients. Combined pharmacological and endovascular strategies will play an increasing role in management of these patients in the future.

Drug therapy for improving walking distance in intermittent claudication: a systematic review and meta-analysis of robust randomised controlled studies

OBJECTIVES

To evaluate the efficacy of pharmacological interventions in improving walking capacity and health-related quality of life for people with intermittent claudication. DATASOURCES: We searched Medline, EMBASE, Cochrane library and relevant websites for studies published from the start of the databases to February 2009. In addition, reference lists were manually searched.

REVIEW METHODS

Based upon a power calculation, only robust (n>56), peer-reviewed, double-blinded, randomised and placebo-controlled trials were included. The main outcomes evaluated were maximal walking distance (MWD) and pain-free walking distance on a treadmill. Random models were used in the statistical analysis, and chi-square test were used to test for heterogeneity.

RESULTS

Among 220 trials, only 43 trials fulfilled the quality criteria. Treatment periods, follow-up and treadmill protocols varied substantially. Vasodilator agents and phosphodiesterase inhibitors show robust significant results compared to placebo, but the improvements in MWD are modest. The highest benefit was caused by lipid-lowering agents, which in mean gained above 160 m in MWD, while the other agents only improved MWD about 50 m.

CONCLUSION

Several drugs have shown to improve MWD, but with limited benefits. Statins seem to be the most efficient drug at the moment.

Pharmacologic therapy for intermittent claudication

Peripheral artery disease, defined as atherosclerosis in the lower extremities, affects nearly 8.5 million people in the United States. Due to the frequent asymptomatic manifestation of peripheral artery disease, diagnosis may be delayed and its true incidence underestimated. However, some patients may experience aching pain, numbness, weakness, or fatigue, a condition termed intermittent claudication. Peripheral atherosclerosis is associated with cardiovascular risk and physical impairment; therefore, treatment goals are aimed at decreasing cardiovascular risk, as well as improving quality of life. Little debate exists regarding the management of cardiovascular risk reduction, which consists of both antiplatelet therapy and risk factor modification. Despite recently published guidelines, the treatment of intermittent claudication is less well established and the management remains controversial and uncertain. Exercise remains the first-line therapy for intermittent claudication; however, pharmacologic treatment is often necessary. Although only two prescription drugs have been approved by the U.S. Food and Drug Administration for the treatment of intermittent claudication, several supplements and investigational agents have been evaluated. Therapeutic optimization should balance the anticipated improvements in quality of life with the potential safety risks.

Opinions on chelation therapy in patients undergoing coronary angiography: cross-sectional survey

BACKGROUND

Chelation therapy is frequently used by patients for the treatment of coronary artery disease. However, relatively little is known about patient attitudes and beliefs that underlie the use of this treatment. The aim of the present study was to document patients' opinions and beliefs about health care decision making, physician and patient communication and relationships, and reasons for using or not using chelation therapy as treatment for coronary artery disease.

METHODS

A mail survey was sent to patients who underwent coronary angiography between 1998 and 2000 in Alberta. Information was collected on self-reported reasons for chelation therapy use, sociodemographic characteristics, communication and relationships between patients and physicians, as well as beliefs regarding surgery, medications and chelation therapy.

RESULTS

Of the 780 patients who received surveys, 96 users and 264 nonusers of chelation therapy completed questionnaires. Among the users, 20.8% believed that chelation therapy could cure heart disease, 44.2% believed that it could relieve symptoms, 16.7% believed that it could have side effects and 58.4% believed that it could increase quality of life. Users and nonusers were similar in their beliefs about safety and benefits of heart surgery, but users of chelation therapy were less likely than nonusers to believe that using conventional medications could prevent worsening of heart disease (53.1% versus 67.4%), increase quality of life (74.0% versus 85.2%) and give a feeling of control over heart disease (61.5% versus 77.7%).

CONCLUSIONS

Many chelation therapy users appeared to have negative views toward the benefits of conventional medications and positive views toward the safety of chelation therapy. Users and nonusers of chelation therapy had the same views toward the benefits and safety of heart surgery.

The role of complementary and alternative therapies in cardiac rehabilitation: a systematic evaluation

BACKGROUND

Presently, complementary and alternative medicine, including both therapies and herbal/oral supplements, is used globally. Few studies have examined the use of specific therapies, separate from herbal/oral supplements, in cardiac rehabilitation. This paper presents a systematic evaluation of current research evidence related to use of specific complementary and alternative medicine therapies in secondary prevention of cardiovascular disease, with a view to making recommendations for cardiac rehabilitation.

DESIGN AND METHODS

A literature search was conducted using complementary and alternative medicine websites, Medline, Allied and Complementary Medicine, CINAHL, Cochrane databases, EMBASE, SportDiscus, Clinical Evidence, and Evidence-Based Practice to locate research-based scientific evidence related to the use of complementary and alternative medicine in cardiac rehabilitation. Search keywords included heart, cardiac, cardiovascular, coronary, myocardial and rehabilitation, combined with particular therapies. Herbal/oral supplements were not included in this evaluation.

RESULTS

Some complementary and alternative medicine therapies may be useful to patients by themselves or coupled with traditional cardiac rehabilitation. Tai chi, as a complement to existing exercise interventions, can be utilized for low and intermediate risk patients. transcendental meditation may be used as a stress reduction technique. There was insufficient evidence found for the use of acupuncture or chelation therapy in cardiac rehabilitation or secondary prevention.

CONCLUSIONS

Some complementary and alternative medicine therapies hold promise for patients in cardiac rehabilitation. Further research is essential, however, in all areas of complementary and alternative medicine to confirm its usefulness as an adjunct to cardiac rehabilitation.

EDTA chelation therapy for cardiovascular disease: a systematic review

Background

Numerous practitioners of both conventional and complementary and alternative medicine throughout North America and Europe claim that chelation therapy with EDTA is an effective means to both control and treat cardiovascular disease. These claims are controversial, and several randomized controlled trials have been completed dealing with this topic. To address this issue we conducted a systematic review to evaluate the best available evidence for the use of EDTA chelation therapy in the treatment of cardiovascular disease.

Methods

We conducted a systematic review of 7 databases from inception to May 2005. Hand searches were conducted in review articles and in any of the trials found. Experts in the field were contacted and registries of clinical trials were searched for unpublished data. To be included in the final systematic review, the studies had to be randomized controlled clinical trials.

Results

A total of seven articles were found assessing EDTA chelation for the treatment of cardiovascular disease. Two of these articles were subgroup analyses of one RCT that looked at different clinical outcomes. Of the remaining five studies, two smaller studies found a beneficial effect whereas the other three exhibited no benefit for cardiovascular disease from the use of EDTA chelation therapy. Adverse effects were rare but those of note included a few cases of hypocalcemia and a single case of increased creatinine in a patient on the EDTA intervention.

Conclusion

The best available evidence does not support the therapeutic use of EDTA chelation therapy in the treatment of cardiovascular disease. Although not considered to be a highly invasive or harmful therapy, it is possible that the use of EDTA chelation therapy in lieu of proven therapy may result in causing indirect harm to the patient.

Inhibition of CEM calcification by the sequential pretreatment with ethanol and EDTA

The major object of the present study is to optimize the anticalcification activity of ethanol on bioprosthetic heart valve (BHV) calcification. We hypothesize that the chelating agent, in combination with ethanol, will synergistically prevent aortic wall calcification. Collagen-elastin matrix (CEM) was developed as a calcifiable matrix for simulating the calcification process of implantable biomaterials. The efficacy of the combination effects of ethanol and EDTA on the calcification process of CEMs was investigated by implanting them after pretreatment with various conditions of ethanol and EDTA in the rat subdermal model. The relationship between calcium concentrations and pretreatment conditions (a series vs. simultaneous, i.e., first ethanol and then EDTA in water solution, the reverse, or EDTA in ethanol) was established and the optimal condition for prevention of BHV calcification was determined. The mechanistic studies on anticalcification effects exerted by particular pretreatment sequences were also conducted using FTIR and differential scanning calorimetry (DSC). The sequential pretreatment of CEM first with ethanol and then EDTA in water solution significantly decreased the calcification rate of CEM compared the control. The percentage of prevention of calcification by the serial treatment of ethanol (80% v/v) and then EDTA in water solutions decreased, as the concentration of elastin in the CEM increased. The percentage of preventing calcification was 42%, 28.6%, and 22.9% for CEM containing collagen and elastin ratios of 90:10, 50:50, 20:80, respectively. These results indicate that elastin is the major regulatory component of BHV calcification, and preventive effects on calcification increased only when CEM were pretreated with first ethanol and then EDTA in water solution. Moreover, the sequential effect is more apparent in the matrix of less elastin content, which is close to the physiological range. The sequential inhibitory effects of ethanol and EDTA could occur due to the distinct separate actions of each agent, thereby achieving a relatively greater inhibition of calcification.

Chelation therapy for atherosclerotic cardiovascular disease

BACKGROUND

Chelation therapy is being promoted and practiced all over the world as a form of alternative medicine in the treatment of atherosclerotic cardiovascular disease. It has been recommended as a safe, relatively inexpensive and non-surgical method of restoring blood flow in atherosclerotic vessels. At present the benefit of chelation therapy remains controversial at best.

OBJECTIVES

The objective of this review is to assess the effects of ethylene diamine tetraacetic acid (EDTA) chelation therapy on clinical outcomes among patients with atherosclerotic cardiovascular disease.

SEARCH STRATEGY

The reviewers searched the Cochrane Peripheral Vascular Diseases Group Trials Register, (last searched July 2002), the Cochrane Controlled Trials Register, (Cochrane Library Issue 2, 2002), MEDLINE and EMBASE for published articles and other relevant articles. Studies were also requested through correspondence with known Filipino practitioners of the procedure.

SELECTION CRITERIA

Studies were included if they were randomized controlled trials of EDTA chelation therapy versus placebo or no treatment in patients with atherosclerotic cardiovascular disease. Main outcome measures considered included either total or cause-specific mortality, non-fatal cardiovascular events, direct or indirect measurement of disease severity, subjective measures of improvement or adverse events.

DATA COLLECTION AND ANALYSIS

Two reviewers (MVV, FT) extracted data and assessed trial quality independently. Unresolved issues were considered by a third reviewer (ALD). Discrepancies were discussed until a consensus was reached. Authors were contacted for additional information.

MAIN RESULTS

A total of five studies was included in the review. Mortality, non-fatal events, and cerebrovascular events were not reported in any of the studies. Four of the studies, with a total recruitment rate of 250 participants, showed no significant difference in the following outcomes: direct or indirect measurement of disease severity and subjective measures of improvement. One of the studies, which included only 10 patients, was interrupted prematurely, because of an apparent treatment effect. However, relevant data were not available in the report and have been requested from the authors.

REVIEWER'S CONCLUSIONS

At present, there is insufficient evidence to decide on the effectiveness or ineffectiveness of chelation therapy in improving clinical outcomes of patients with atherosclerotic cardiovascular disease. This decision must be preceded by conducting randomized controlled trials that would include endpoints that show the effects of chelation therapy on longevity and quality of life among patients with atherosclerotic cardiovascular disease.

Use of chelation therapy after coronary angiography

PURPOSE

Among patients who had undergone coronary angiography, we sought to determine the proportion of chelation therapy users, their sociodemographic and clinical characteristics, and the association of chelation therapy with subsequent revascularization.

METHODS

We studied all patients who underwent coronary angiography in the province of Alberta, Canada, during 1995 and 1996. The cohort was followed for up to 6 years to determine subsequent revascularization status. Use of chelation therapy was determined by a mailed survey 1 year after angiography.

RESULTS

Among the 5854 patients who responded to the mail survey (70% response rate), 210 (3.6%) reported current use of chelation therapy and 252 (4.3%) reported past use. Current use of chelation therapy was associated with extensive coronary artery disease (adjusted odds ratio [OR] = 3.3; 95% confidence interval [CI]: 1.9 to 5.7 for 3-vessel disease; and OR = 2.7; 95% CI: 1.2 to 6.0 for left main disease, as compared with those with normal anatomy) and the absence of diabetes (OR = 0.6; 95% CI: 0.4 to 0.9). Current users were less likely to have undergone percutaneous transluminal coronary angioplasty (OR = 0.7; 95% CI: 0.5 to 0.9) and coronary artery bypass graft (CABG) surgery (OR = 0.3; 95% CI: 0.2 to 0.5) in the first year after angiography, but were as likely as nonusers of chelation therapy to have undergone CABG surgery in the subsequent 3- to 5-year period (adjusted hazard ratio [HR] = 1.1; 95% CI: 0.7 to 1.9). Past use of chelation therapy was associated with a history of CABG surgery before coronary angiography (OR = 1.6; 95% CI: 1.1 to 2.3) and extensive coronary artery disease. Past users were also more likely to have undergone CABG surgery in the follow-up period (HR = 1.7; 95% CI: 1.1 to 2.6).

CONCLUSIONS

About 8% of patients who underwent cardiac catheterization for coronary artery disease were using or had previously tried chelation therapy. Users may have foregone revascularization in favor of this less invasive yet unproven treatment, with some users subsequently undergoing conventional treatment after chelation. Alternatively, some patients may have turned to chelation as a "last resort" after having been judged unsuitable for revascularization.

Effects of chelation with EDTA and vitamin B therapy on nitric oxide-related endothelial vasodilator function

1. 'Chelation therapy' with EDTA is being frequently used in patients with cardiovascular disease, despite limited objective evidence of effectiveness. Depressed nitric oxide (.NO)-related endothelial function accompanies atherosclerosis, and even the vascular risk factors alone, and is improved by numerous interventions that also improve prognosis in vascular disease. 2. The aim of the present study was to determine the influence of chelation therapy with EDTA alone and EDTA in combination with B vitamins on endothelial function. 3. After a control series of saline infusions, we examined the effects of a series of EDTA infusions (1.5 g, 10 times over 6 weeks) in eight subjects with coronary artery disease. In addition, because EDTA is commonly supplemented by other components, particularly B group vitamins, we subsequently examined the effect of a similar series of vitamin-supplemented EDTA infusions. 4. Forearm blood flow (FBF) was assessed by plethysmography and graded intrabrachial infusions of the endothelium-dependent vasodilator acetylcholine (ACh) and the endothelium-independent dilator sodium nitroprusside (SNP). 5. There was no difference in vasodilation to either drug after EDTA alone compared with the control periods, but the response to ACh was augmented after combined therapy (P < 0.03, ANOVA). The latter was accompanied by a small but consistent mean (+/- SEM) fall in plasma homocysteine of 1.6 +/- 0.5 mumol/L (P < 0.05). 6. The selective increase in the vasodilator response to ACh after therapy with EDTA and several B group vitamins indicates that NO-related endothelial function was improved. The absence of response to EDTA alone suggests that the supplementary vitamins were necessary for this benefit, which may have been related to the accompanying decrease in plasma homocysteine. These results, along with the current interest in the possible cardioprotective effects of vitamins and the increasing administration of 'chelation therapy', call for more definitive studies on these aspects of 'alternative medicine'.