Prevalence of subclinical cardiac abnormalities in patients with metal-on-metal hip replacements.

BACKGROUND

Metal-on-metal (MOM) hip prostheses have a higher failure rate than conventional prostheses and leaching of cobalt and chromium has been linked to cardiomyopathy. We screened MOM subjects to evaluate if cobalt and chromium are related to subclinical cardiac dysfunction.

METHODS

A single centre, non-randomised, observational study using echocardiography in 95 patients who had undergone MOM hip prostheses, and 15 age matched controls with non-MOM hip replacement. Serial plasma cobalt and chromium levels were recorded, and data compared by tertiles of cobalt exposure.

RESULTS

Indexed left ventricular (LV) end-diastolic and end-systolic volumes (EDVi and ESVi) increased with tertile of cobalt (omnibus p = 0.003 for EDVi and ESVi), as did indexed left atrial (LA) volumes (p = 0.003). MOM subjects had 25% larger EDVi than controls, 32% larger ESVi (40 ml vs. 32 ml, and 15 ml vs. 11 ml, p = 0.003 for both) and 28% larger indexed LA (23 ml vs. 18 ml, p = 0.002). There were no differences in LV systolic or diastolic function, including ejection fraction, tissue velocity and mitral E/e'. Estimated glomerular filtration rate was 18% lower in the highest tertile compared with the lowest (p = 0.01) and correlated inversely with LA volume (r = -0.36, p < 0.001) and LV EDV (r = -0.24, p = 0.02).

CONCLUSIONS

No correlations between sensitive measures of systolic or diastolic cardiac function or serum cobalt/chromium levels were observed in this study. However, there was a relationship between increasing left ventricular and left atrial volumes and declining renal function with high cobalt levels which requires further evaluation in MOM patients.

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