Evaluation of Cobalt and Chromium Levels Following Implantation of Cobalt Chromium Coronary Stents: A Pilot Study

Association between metal implants and urinary chromium levels in US adults: a cross-sectional study from NHANES

Metal implants play a significant role in orthopedics, commonly used for treating fractures, joint replacement surgeries, spinal procedures, and more. Chromium (Cr), crucial in these implants, may raises health concerns. However, the relationship between metal implants and urine Cr levels remains uncertain. We aimed to evaluate this relationship. We conducted a cross-sectional study on 1419 individuals aged 40 years or older using data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2017 to 2020. Multivariate linear regression models and subgroup analysis were applied to assess associations between metal implants and urine Cr levels. Among the 1419 participants, 402 [28.3%] self-reported having metal objects in their bodies. After adjusting for potential confounding factors, metal implants were positively correlated with the accumulation of urine Cr (β = 0.41, 95% CI 0.04-0.77, p = 0.028). However, the positive correlation of metal implants with urine Cr was only present in females (β = 0.81, 95% CI 0.08-1.53, p = 0.029), but not in males. Our study revealed higher urine Cr levels in individuals with metal implants, with noticeable gender differences. Additionally, those with metal implants exhibited a more pronounced elevation in urine Cr levels with increasing age compared to individuals without implants.

Accumulation of blood chromium and cobalt in the participants with metal objects: findings from the 2015 to 2018 National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Chromium (Cr) and cobalt (Co) are the essential elements for producing metal implants, but might have potential health issues. The research on the correlation between metal implants and blood Cr and Co on a large population is still limited.

METHODS

National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health status of Americans began in the early 1960s. The study was based on the NHANES database from two data collection years (2015-2016 and 2017-2018). The exposure variable of this study was whether the participants had metal objects in the body or not. The outcome variables were blood concentrations of Cr and Co. Age, body mass index, sex, race/ethnicity, income to poverty ratio, tap water behavior, shellfish/fish/tuna/salmon eating habits, level of education, smoking behavior, marital status, blood hemoglobin, and data collection years were included as confounding variables.

RESULTS

A total of 4412 participants, aged 40 years or older, were included in this analysis, consisting of the without metal objects group (n = 3150) and the metal objects group (n = 1262). Metal objects was positively correlated to the accumulation of blood Cr (β = 0.072, 95% CI: 0.043-0.102, p < 0.001) and blood Co (β = 0.079, 95% CI: 0.049-0.109, p < 0.001). However, the positive correlation of metal objects with blood Cr was only presented in women (β = 0.112, 95% CI: 0.074-0.151, p < 0.001), but not in men. Meanwhile, the positive relationship between metal objects and blood Cr/Co was not observed in the Asian subgroup.

CONCLUSIONS

Blood Cr and Co concentrations were statistically higher in people with metal objects, but with race and sex differences.

LEVEL OF EVIDENCE

Level IV, cross-sectional study.

An integrated benefit-risk assessment of cobalt-containing alloys used in medical devices: Implications for regulatory requirements in the European Union

In 2017, the European Union (EU) Committee for Risk Assessment (RAC) recommended the classification of metallic cobalt (Co) as Category 1B with respect to its carcinogenic and reproductive hazard potential and Category 2 for mutagenicity but did not evaluate the relevance of these classifications for patients exposed to Co-containing alloys (CoCA) used in medical devices. CoCA are inherently different materials from Co metal from a toxicological perspective and thus require a separate assessment. CoCA are biocompatible materials with a unique combination of properties including strength, durability, and a long history of safe use that make them uniquely suited for use in a wide-range of medical devices. Assessments were performed on relevant preclinical and clinical carcinogenicity and reproductive toxicity data for Co and CoCA to meet the requirements under the EU Medical Device Regulation triggered by the ECHA re-classification (adopted in October 2019 under the 14th Adaptation to Technical Progress to CLP) and to address their relevance to patient safety. The objective of this review is to present an integrated overview of these assessments, a benefit-risk assessment and an examination of potential alternative materials. The data support the conclusion that the exposure to CoCA in medical devices via clinically relevant routes does not represent a hazard for carcinogenicity or reproductive toxicity. Additionally, the risk for the adverse effects that are known to occur with elevated Co concentrations (e.g., cardiomyopathy) are very low for CoCA implant devices (infrequent reports often reflecting a unique catastrophic failure event out of millions of patients) and negligible for CoCA non-implant devices (not measurable/no case reports). In conclusion, the favorable benefit-risk profile also in relation to possible alternatives presented herein strongly support continued use of CoCA in medical devices.

First in man study of a new semi-open cell design Zephyr cobalt-chromium stent in large vessels and conduits

OBJECTIVES

We present a first-in-man clinical use of a new hybrid design stent in stenosed large vessels. Its unique C and S polylinks prevent foreshortening without compromising its strength. Its thin profile permits use of smaller introducer sheaths.

BACKGROUND

Stent angioplasty is widely employed in large vessel and conduit stenosis. These procedures are associated with difficulties due to large stent profiles, stent fractures, foreshortening and recoil. Cobalt chromium stents have high tensile strengths compared to stainless steel stents.

METHODS

A retrospective analysis of feasibility and safety of a new Cobalt chromium stent in large vessels namely aorta, pulmonary arteries and outflow conduits was done from two institutions. Demographic patient details, procedural results, complications and medium term follow-up were analyzed. Stent recoil, foreshortening, fractures were assessed.

RESULTS

Twenty patients including three with aortic coarctations, seven with stenosed conduits and 10 with pulmonary artery stenosis underwent stent angioplasty using 23 stents. Three stents were deployed to expand further a previously implanted stent. Procedure was successful in all patients, lumen increased by 150-300%, gradients reduced in all patients. There was no stent recoil, foreshortening or fractures. There were no complications. At a follow up of 3-27 months, there were no stent related complications and the gradients remained stable.

CONCLUSIONS

The new Zephyr stent was useful in a wide variety of stenotic lesions involving large vessels including those that were previously stented. Lack of stent recoil and foreshortening seems to be an advantage for this new stent that needs validation in larger multicenter studies.