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[
    {
        "fact": "Text segment from the original document. Note that Chinese quotation marks should use full-width marks. And add a single backslash before the English quotation mark to make it a readable for python json module.",
        "ref_idx": "The index of the cited reference in the reference list for this text segment.",
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    }
]

Here is the main text of the research report:
# Modulating Plasma Metal Ions to Prevent or Treat Cardiovascular Disease: An Evidence-Based Analysis

## TL;DR

- **Metal-ion modulation is a real but narrow therapeutic strategy in cardiovascular medicine: the one intervention with guideline-endorsed, outcome-changing evidence is intravenous iron repletion in iron-deficient heart failure. Correcting a genuine deficiency or overload (iron, copper, selenium in deficient populations) works; broadly supplementing metals in replete people or chelating "toxic" metals in unselected patients does not.**
- **EDTA chelation, once promising after TACT (2013), was refuted by the larger, better-controlled TACT2 (2024), which showed no cardiovascular benefit despite effectively lowering blood lead and cadmium. Toxic metals (lead, cadmium, arsenic) are now recognized causal CVD risk factors, but the answer is exposure prevention, not chelation.**
- **Most oral supplementation (selenium, zinc, magnesium, calcium) shows benefit only in deficiency states or on surrogate markers (blood pressure, arrhythmia), not hard outcomes in replete populations; calcium supplements may modestly increase MI risk. Copper chelation for cardiac hypertrophy (trientine) is the most promising emerging pharmacological approach but remains phase 2.**

## Key Findings

1. **Iron is the standout success.** IV iron (ferric carboxymaltose/derisomaltose) in iron-deficient HFrEF/HFmrEF reduces heart-failure hospitalizations. The 2025 individual-participant meta-analysis by Anker SD et al. (*Nature Medicine* 2025;31(8):2640–2646) of six trials (7,175 patients) found patients assigned to IV iron "had lower rates for the composite endpoint of recurrent HF hospitalizations and cardiovascular mortality at 12 months (risk ratio (RR) = 0.72 (95% confidence interval (CI) = 0.55–0.89))." [nih](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12353798/)[Nature](https://www.nature.com/articles/s41591-025-03671-1) This underpins Class I (symptoms/QoL) and Class IIa (hospitalization reduction) recommendations in the 2023 ESC HF guideline update.
2. **EDTA chelation failed replication.** TACT (Lamas GA et al., *JAMA* 2013) suggested an 18% CVD-event reduction in 1,708 post-MI patients with a 41% reduction in the diabetic subgroup; TACT2 (Lamas GA et al., *JAMA* 2024;332(10):794–803), which randomized 1,000 diabetic post-MI patients across 88 US/Canadian sites, found no benefit (35.6% vs 35.7% events) despite a 61% reduction in blood lead.
3. **Toxic metals are causal CVD risk factors** (AHA 2023 scientific statement), but the intervention is prevention of exposure, not chelation treatment.
4. **Selenium/CoQ10** reduced CV mortality in a Swedish trial of selenium-deficient elderly (KiSel-10), but selenium in replete populations (SELECT) showed no CV benefit.
5. **Copper chelation (trientine)** reduces LV mass in diabetic heart disease and, in the newly published phase 2 TEMPEST trial, in hypertrophic cardiomyopathy—an emerging, mechanistically novel approach.

## Details

### 1. Background and mechanisms

Metal ions participate in cardiovascular pathophysiology through several converging mechanisms:

- **Redox chemistry / oxidative stress:** Redox-active metals (iron, copper) catalyze Fenton and Haber-Weiss reactions generating reactive oxygen species (ROS), driving lipid peroxidation, oxidation of LDL, and endothelial injury. Iron-dependent lipid peroxidation defines **ferroptosis**, a regulated cell-death pathway now implicated in atherosclerosis, ischemia-reperfusion injury, myocardial infarction, heart failure, and doxorubicin cardiomyopathy.
- **Enzyme cofactor roles:** Selenium is incorporated into selenoproteins (glutathione peroxidases, thioredoxin reductases) central to antioxidant defense. Copper is a cofactor for cytochrome c oxidase (mitochondrial respiration), superoxide dismutase (SOD1), lysyl oxidase (connective-tissue crosslinking), and ceruloplasmin. [PubMed Central](https://pmc.ncbi.nlm.nih.gov/articles/PMC2671677/) Zinc is a structural/catalytic cofactor for roughly 10% of the human proteome, [biorxiv](https://www.biorxiv.org/content/10.1101/2025.10.17.683119.full.pdf) including Cu/Zn-SOD, and is chemically inert (acting as an antioxidant partly by displacing redox-active metals).
- **Endothelial dysfunction and inflammation:** Toxic metals (lead, cadmium, arsenic) and metal dyshomeostasis promote endothelial dysfunction, vascular inflammation (VCAM-1, ICAM-1, MCP-1 upregulation), and disturbed lipid metabolism.
- **Myocardial function:** Selenium deficiency causes Keshan disease (dilated cardiomyopathy); copper deficiency causes cardiac hypertrophy and heart failure in models; iron overload causes iron-overload cardiomyopathy; iron deficiency impairs mitochondrial energetics in cardiomyocytes.
- **Vascular calcification:** Calcium-phosphate (hydroxyapatite) deposition in the arterial intima and media drives coronary artery calcification; zinc suppresses phosphate-induced vascular calcification in vitro.
- **Metallothioneins:** Cysteine-rich, low-molecular-weight metal-binding proteins that buffer zinc, scavenge free radicals, and detoxify heavy metals; cardioprotective in overexpression models (e.g., MT-IIA-overexpressing cardiac cell lines confer oxidative protection).

### 2. Types of interventions proposed

**Essential trace element supplementation** — zinc, selenium, magnesium, copper, iron. Rationale is repletion of deficiency; efficacy depends critically on baseline status.

**Chelation therapy** — EDTA (edetate disodium) for lead/cadmium/calcium; DMSA and others for heavy metals; copper-selective chelators (trientine, tetrathiomolybdate); iron chelators (deferoxamine, deferasirox, deferiprone) for overload.

**Dietary interventions** — reducing toxic-metal intake (contaminated water/food), Mediterranean-diet fish intake balancing omega-3 benefit against methylmercury, dietary magnesium and zinc.

**Pharmacological metal-homeostasis modulation** — copper chelation for cardiac remodeling; iron-restriction/ferroptosis inhibitors (investigational); hepcidin pathway modulation.

**Metal-binding proteins / metallothionein modulation** — largely preclinical; metallothionein overexpression is cardioprotective against oxidative stress.

**Novel approaches** — SNF472 (hexasodium phytate, an intravenous hydroxyapatite-crystallization inhibitor) for vascular calcification; nanoparticle and ionophore approaches remain experimental.

### 3. Iron and cardiovascular disease

**Iron deficiency in heart failure (the strongest evidence base):**

- **AFFIRM-AHF** (acute HF, ferric carboxymaltose) and **IRONMAN** (chronic HF, ferric derisomaltose) both narrowly missed their primary composite endpoints but showed benefit in pre-specified COVID-adjusted analyses.
- **HEART-FID** (3,065 patients, ferric carboxymaltose; *NEJM* 2023) did not reach significance at the pre-specified 99% CI but was significant at the conventional 95% CI.
- **2025 Nature Medicine meta-analysis** (Anker SD et al., *Nat Med* 2025;31(8):2640–2646; FAIR-HF, CONFIRM-HF, AFFIRM-AHF, IRONMAN, HEART-FID, FAIR-HF2; 7,175 patients; Bayesian, individual-participant data): RR 0.72 (95% CI 0.55–0.89) for recurrent HF hospitalizations plus CV death at 12 months; RR 0.81 (0.63–0.97) over full follow-up.
- **ESC 2023 focused update:** IV iron Class I (Level A) to improve symptoms/QoL; Class IIa (Level A) to reduce HF hospitalization in symptomatic HFrEF/HFmrEF with iron deficiency [American College of Cardiology](https://www.acc.org/Latest-in-Cardiology/ten-points-to-remember/2023/08/29/14/58/2023-focused-update-esc-guidelines-hf-esc-2023) (defined as ferritin <100 ng/mL, or 100–299 with TSAT <20%).

**Iron overload:** Hereditary hemochromatosis and transfusion-dependent β-thalassemia cause iron-overload cardiomyopathy (diastolic dysfunction and arrhythmias progressing to systolic failure); in inherited hemochromatosis, cardiac iron damage is a leading cause of death. Management is phlebotomy or iron chelation (deferoxamine, deferasirox, deferiprone) with cardiac MRI T2* monitoring. Ferroptosis and macrophage iron overload contribute to atherosclerosis progression in models.

### 4. Selenium

- **Keshan disease:** endemic selenium-deficiency dilated cardiomyopathy in low-selenium regions of China (first described 1935); selenium salt supplementation dramatically reduced incidence. In chronic Keshan disease with congestive heart failure, a 10-year follow-up found selenium supplementation associated with reduced cardiac death (HR 0.39, 95% CI 0.28–0.53).
- **KiSel-10 (Alehagen et al.):** Swedish RCT, 443 elderly with low selenium, 200 µg/day selenized yeast + 200 mg/day CoQ10 for 48 months. Reduced CV mortality persisting long after the intervention ended: HR 0.51 (95% CI 0.36–0.74; P=0.0003) at 10 years (*PLoS One* 2015;10(12):e0141641), and at 12 years CV mortality was 28.1% (active) vs 38.7% (placebo), HR 0.59 (95% CI 0.42–0.81; P=0.001) (*PLoS One* 2018;13(4):e0193120).
- **SELECT:** 35,533 men, 200 µg L-selenomethionine ± vitamin E; no reduction in prostate cancer and no CV benefit (the population was selenium-replete). Vitamin E was associated with a 17% increased prostate cancer risk.
- **Interpretation:** Benefit appears confined to selenium-deficient populations. High selenium has been associated with increased hypertension and type 2 diabetes risk—consistent with a U-shaped exposure-risk relationship.

### 5. Zinc

Zinc deficiency is associated with atherosclerosis, myocardial infarction, and ischemia-reperfusion injury in mechanistic studies, acting via anti-oxidant and anti-inflammatory pathways and metallothionein induction. A GRADE-assessed dose-response meta-analysis found zinc supplementation improved lipid and glycemic risk factors for type 2 diabetes and CVD; doses studied ranged from ~9.8 to 75 mg/day elemental zinc. In patients with type 2 diabetes and coronary heart disease, magnesium (250 mg) plus zinc (150 mg zinc sulfate) co-supplementation for 12 weeks improved fasting glucose, insulin, HDL, and CRP. In hemodialysis populations, low zinc predicts mortality and supplementation improves oxidative-stress markers. Evidence is on surrogate markers, not hard CVD outcomes.

### 6. Magnesium

- **Blood pressure:** 2025 meta-analysis (38 RCTs, 2,709 participants, median 365 mg/day elemental magnesium): SBP −2.81 mmHg (95% CI −4.32 to −1.29), DBP −2.05 mmHg (−3.23 to −0.88) overall; larger reductions in hypertensives on antihypertensive medication (SBP −7.68) and in hypomagnesemic patients (SBP −5.97). No significant effect in normotensives.
- **Arrhythmia:** meta-analysis (22 studies) of magnesium after acute coronary syndrome reduced ventricular arrhythmia (OR 0.32, 95% CI 0.16–0.49) and supraventricular arrhythmia (OR 0.42, 95% CI 0.22–0.65). IV magnesium is established therapy for torsades de pointes and for post-cardiac-surgery atrial fibrillation prophylaxis.

### 7. Copper

- **Deficiency:** causes cardiac hypertrophy, heart failure, and cardiomyopathy in animal models (reduced cytochrome c oxidase, SOD, and lysyl oxidase activity); copper repletion reverses these.
- **Excess/dysregulation:** elevated serum copper/ceruloplasmin correlates with CVD risk and heart-failure severity; cuproptosis (copper-dependent cell death) is an emerging mechanism.
- **Copper chelation (trientine) — the most promising emerging pharmacological approach:**

  
  - **Cooper GJS et al. (*Diabetologia* 2009;52(4):715–722):** 12-month randomized, double-blind, placebo-controlled trial in 30 type-2-diabetic patients with LV hypertrophy; trientine 1,200 mg/day. LV mass index by cardiac MRI fell −10.6 ± 7.6 g/m² (trientine) vs −0.1 ± 9.8 g/m² (placebo) at 12 months (P=0.0088), without changes in blood pressure or glycemia. [springer](https://link.springer.com/article/10.1007/s00125-009-1265-3) Notably small (n=15/group, only 9 trientine patients analyzed at 12 months) and industry-linked (Protemix).
  - **TEMPEST (phase 2, hypertrophic cardiomyopathy; Farrant JP et al.):** multicentre, double-blind, placebo-controlled trial; 154 randomized (79 trientine, 75 placebo), 800 mg/day trientine base for 52 weeks. [lancashire](https://knowledge.lancashire.ac.uk/id/eprint/59790/1/59790%20Farrant%20et%20al.%20VOR.pdf) Primary endpoint change in LV mass index by CMR: −4.4 g/m² (trientine) vs −1.5 g/m² (placebo), between-group difference −3.2 g/m² (95% CI −5.6 to −0.8; P=0.009), with greater effect at higher baseline LV mass and mediation via reduced myocardial cellular mass. [lancashire](https://knowledge.lancashire.ac.uk/id/eprint/59790/1/59790%20Farrant%20et%20al.%20VOR.pdf) Well tolerated (more anemia and hypocupraemia with trientine). [lancashire](https://knowledge.lancashire.ac.uk/id/eprint/59790/1/59790%20Farrant%20et%20al.%20VOR.pdf) The design was published in *Heart* 2023;109:1175–1182 (NCT04706429); the trial is the first non-sarcomere-targeted therapy to reduce LV mass in HCM, [lancashire](https://knowledge.lancashire.ac.uk/id/eprint/59790/1/59790%20Farrant%20et%20al.%20VOR.pdf) but phase 3 trials with clinical endpoints are required.
- **Tetrathiomolybdate:** copper chelation reduced atherosclerotic lesion development by ~25% (whole aorta) to ~45% (descending aorta) in ApoE-deficient mice [PubMed](https://pubmed.ncbi.nlm.nih.gov/22770994/) (Wei H et al., *Atherosclerosis* 2012;223:306–313), with reduced vascular inflammation; no human cardiovascular outcome trials exist (human use has been in Wilson's disease and oncology).

### 8. Toxic heavy metals (lead, cadmium, arsenic, mercury)

- **AHA 2023 scientific statement** (*J Am Heart Assoc*): chronic low/moderate exposure to lead, cadmium, and arsenic increases the risk of coronary artery disease, stroke, and peripheral artery disease; environmental cardiology now treats these as modifiable risk factors.
- **Lead:** Lanphear BP et al. (*Lancet Public Health* 2018; NHANES-III cohort of 14,289 adults) estimated ~256,000 premature CVD deaths per year in the US attributable to lead (including ~185,000 from ischaemic heart disease), [Scimex](https://www.scimex.org/newsfeed/almost-1-in-5-deaths-in-the-us-could-be-because-of-lead) of ~412,000 total lead-attributable deaths (18% of all mortality); [The Lancet](https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30043-4/fulltext) CVD-mortality HR 1.70 (95% CI 1.30–2.22) comparing the 90th vs 10th percentile of blood lead. [The Lancet](https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30043-4/fulltext) Pooled RRs (high vs low blood lead) elsewhere: 1.43 for CVD, 1.85 for CHD, 1.63 for stroke.
- **Cadmium:** 2023 meta-analysis (21 studies): RR 1.36 (95% CI 1.22–1.50) for CVD, 1.73 for heart disease, 1.28 for stroke; separate dose-response meta-analyses confirm positive associations with hypertension. (Smoking is a major cadmium source—an important confounder.)
- **Arsenic:** Strong Heart Study—each interquartile increase in urinary arsenic (12.5 µg/L) associated with all-cause mortality HR 1.28 and CV mortality HR 1.28; low-to-moderate exposure linked to incident CVD, with mechanisms including oxidative stress, inflammation, and endothelial dysfunction.
- **Mercury:** methylmercury from fish is neurotoxic and may increase CV risk by inhibiting selenoenzymes, but selenium co-ingestion and omega-3 benefits complicate the picture; the PREDIMED nested case-control study found no increased CVD risk from mercury exposure in high-fish-consuming Spanish adults (fully-adjusted RR 0.71 for highest vs lowest quartile).
- **Intervention:** The consensus is exposure reduction (regulation, water/soil/air monitoring, abatement); chelation is not recommended for cardiovascular prevention (see TACT2 below).

### 9. EDTA chelation therapy

- **TACT (Lamas GA et al., *JAMA* 2013;309(12):1241–1250):** 1,708 post-MI patients; 40 EDTA infusions; a significant 18% reduction in the composite endpoint (cardiac event in 26% chelation vs 30% placebo); a large benefit in the pre-specified diabetic subgroup (HR 0.59, 95% CI 0.44–0.79) with a 41% relative reduction. The authors cautioned these results were not sufficient to support routine use.
- **TACT2 (Lamas GA et al., *JAMA* 2024;332(10):794–803):** 1,000 diabetic post-MI patients across 88 US/Canadian sites (959 received ≥1 infusion); [American College of Cardiology](https://www.acc.org/latest-in-cardiology/articles/2024/04/02/17/02/sun-945am-tact2-acc-2024) **no benefit**—CV events 35.6% (chelation) vs 35.7% (placebo); CV death/MI/stroke [TCTMD](https://www.tctmd.com/news/edta-chelation-no-help-cutting-cv-outcomes-after-mi-diabetic-patients-tact2) 18.4% vs 19.7%; all-cause death 17.4% vs 17.6%—despite a statistically significant 61% reduction in blood lead [TCTMD](https://www.tctmd.com/news/edta-chelation-no-help-cutting-cv-outcomes-after-mi-diabetic-patients-tact2) (median 9.03→2.46 µg/L) and increased urinary cadmium excretion.
- **Verdict:** The toxic-metal-chelation hypothesis for secondary prevention is not supported by the definitive replication trial. EDTA chelation should not be used to reduce cardiovascular events.

### 10. Calcium

- **Vascular calcification:** the coronary artery calcium score (Agatston) is a strong, specific marker of atherosclerotic burden and predicts CV events; notably, statins reduce events but do not reliably reduce established calcium scores.
- **Calcium supplements and risk:** Bolland et al. meta-analyses found calcium supplements without vitamin D increased MI risk ~27–31% (e.g., HR 1.31, 95% CI 1.02–1.67 in individual-patient analysis of 8,151 subjects); a 2016 *Annals of Internal Medicine* meta-analysis found calcium ± vitamin D increased MI (pooled RR 1.24, 95% CI 1.07–1.45) and stroke (RR 1.15). Other meta-analyses (e.g., 2021, 12 RCTs) found no significant association—evidence is genuinely conflicting, but the signal favors caution with high-dose supplements versus dietary calcium (dietary calcium does not appear to raise risk).
- **SNF472 (hexasodium phytate):** In the CaLIPSO phase 2 trial (Raggi P et al., *Circulation* 2020;141(9):728–739), 274 hemodialysis patients were randomized 1:1:1 to SNF472 300 mg, 600 mg, or placebo [AHA Journals](https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.119.044195) infused thrice weekly during dialysis over 52 weeks; the mean change in coronary artery calcium volume score was "11% (95% CI, 7–15) for the combined SNF472 dose group and 20% (95% CI, 14–26) for the placebo group (P=0.016)." [PubMed](https://pubmed.ncbi.nlm.nih.gov/31707860/) SNF472 (also designated CSL525) inhibits hydroxyapatite crystallization and is being developed for calciphylaxis and cardiovascular calcification; endpoints to date are surrogate imaging, not clinical outcomes.

### 11. Feasibility and safety

- **IV iron:** generally well tolerated; hypophosphatemia (notably with ferric carboxymaltose) and rare hypersensitivity reactions.
- **Selenium:** narrow therapeutic window; excess causes selenosis and is linked to increased hypertension and diabetes risk—supplementation should be reserved for deficiency.
- **Copper chelation (trientine):** anemia and hypocupraemia require monitoring (both seen in TEMPEST); GI side effects.
- **EDTA:** hypocalcemia, potential renal risk, and heavy treatment burden (40 infusions)—with no proven cardiovascular benefit.
- **Calcium supplements:** a possible MI signal argues for favoring dietary sources.
- **Patient selection is decisive:** benefit accrues to those with documented deficiency (iron, selenium) or overload (iron), not to replete populations.

## Recommendations

**Stage 1 — Do now (evidence-based clinical practice):**

- Screen all heart-failure patients (HFrEF/HFmrEF) for iron deficiency (ferritin, TSAT) and treat with IV ferric carboxymaltose or ferric derisomaltose per ESC 2023 (Class I to improve symptoms/QoL; Class IIa to reduce HF hospitalization).
- Correct hypomagnesemia; use IV magnesium for torsades de pointes and post-operative AF prophylaxis; consider magnesium in hypertensive patients with low magnesium status.
- Screen for and treat iron overload (hemochromatosis, thalassemia) with phlebotomy/chelation and cardiac MRI T2* monitoring.
- Counsel patients to reduce toxic-metal exposure (water testing, avoiding contaminated food/water/consumer sources); support public-health abatement.
- **Do NOT** use EDTA chelation for cardiovascular event prevention. Advise caution with high-dose calcium supplements; favor dietary calcium.

**Stage 2 — Consider selectively / individualize:**

- Selenium supplementation only in documented deficiency or low-selenium regions; avoid in replete individuals given the U-shaped risk curve.
- Zinc repletion in documented deficiency (e.g., CKD/hemodialysis), where surrogate benefits exist.

**Stage 3 — Investigational (enroll in trials where available):**

- Copper chelation (trientine) for diabetic cardiomyopathy and hypertrophic cardiomyopathy (phase 3 with clinical endpoints needed).
- SNF472 for vascular calcification in dialysis patients (outcome data needed).
- Ferroptosis inhibitors and metallothionein modulation (preclinical).

**Thresholds that would change recommendations:** A positive phase 3 trientine trial with hard endpoints; positive clinical-outcome data for SNF472; or any adequately powered RCT showing chelation reduces events in a well-defined metal-burdened subgroup would reopen the toxic-metal-chelation question.

## Caveats

- Much of the supplementation evidence rests on **surrogate markers** (blood pressure, lipids, arrhythmia counts, imaging) rather than mortality, MI, or stroke.
- **Baseline status confounds everything:** the same intervention can help the deficient and harm the replete (U-shaped curves for selenium, copper, iron, and calcium). Effect sizes generalize poorly across populations with different baseline metal status.
- Several key HF iron trials (AFFIRM-AHF, IRONMAN, HEART-FID) **missed their primary endpoints** on conventional pre-specification and rely on pre-specified COVID-adjusted or meta-analytic significance; the strong meta-analytic signal is nonetheless consistent.
- Observational metal–CVD associations are vulnerable to **residual confounding** (smoking is a major cadmium source; socioeconomic factors track lead exposure).
- The most cited copper-chelation trial (Cooper 2009) was very small (n=30) and industry-linked; the larger, independent TEMPEST trial found a more modest but statistically significant effect on an imaging surrogate, not clinical outcomes.
- SNF472 and copper-chelation efficacy data remain on **surrogate endpoints**, and their translation to reduced events is unproven.


Please begin the extraction now. Output only the JSON list directly, without any chitchat or explanations.