Yogeswaran, Vidushei

Introduction: One million patients around the world have had total hip arthorplasty with 35% of them having metal-on-metal implants. Although there have been some case reports of cobalt cardiotoxicity from arthroprosthetic cobaltism resulting in dilated cardiomyopathy, incidence of cardiomyopathy and mortality in these patients is unknown. Objective: We therefore sought to determine the incidence of new onset cardiomyopathy (EF <40%) and associated mortality, in patients with metal hip arthroplasty. Methods: We retrospectively examined the records of the patients form our institutional total hip arthroplasty registry (Metal on Metal: MoM, Metal on Polyethylene: MoP, Ceramic on Ceramic: CoC and Ceramic on Polyethylne: CoP). Among 122 patients with baseline and follow up echocardiograms, cobalt and chromium levels were available in 12 patients, none of which developed incident cardiomyopathy. Results: The mean age of the population with metal group (MoM and MoP) was 53 years, predominantly males. During the follow up period of 10 years, the cumulative incidence (KM curve probabilities) of low EF <=40% in our study population was 14% in metal group as compared to 5% in non-metal group (CoC and CoP), (p value 0.51). At 15 years of follow up, among 122 patients, there were16 deaths in the metal group (81) and only 2 deaths in the non-metal group (41) (p value 0.15). Conclusions: In conclusion, although the incidence of cardiomyopathy as well as mortality is low in patients with metal hip arthroplasty and not significantly, further studies maybe needed to assess its effect on diastolic dysfunction.

Background: Worldwide, approximately one million patients have had total hip arthroplasty with 35% being cobalt and chromium Metal-on-Metal (MoM) or Metal-on-Polythelene (MoP) implants. Animal models have suggested that cobalt and chromium can affect all chambers, but there seems to be an atrial predilection. There are several case reports of metal containing hip arthroplasty causing atrial arrhythmias but the true incidence of atrial fibrillation associated with metal hip arthroplasty remains undefined. Objective: We sought to determine the incidence of atrial fibrillation in patients with metal containing hip arthroplasty. We also examined the association between serum cobalt and chromium levels and arrhythmias in this cohort and all cause mortality. Methods: We retrospectively examined the records of patients from the Mayo Clinic total hip arthroplasty registry (Metal group - Metal-on-Metal: MoM and Metal-on-Polyethylene: MoP, Non-Metal group - Ceramic-on-Ceramic: CoC and Ceramic-on-Polyethylne: CoP) to obtain demographic data, comorbidities, laboratory, ECG, and echocardiographic data. Out of a total of 1756 patients, Cobalt and Chromium levels were available in 138 patients. Results: The mean age of patients with metal containing hip replacement was 50 years and were predominantly male. During a follow up period of 10 years, the incidence of atrial fibrillation in our study population was 8% in metal group compared to 2% (p=0.11) in non-metal group. There was no association between cobalt or chromium levels with the incidence of atrial fibrillation. All-cause mortality was significantly higher in metal group versus non-metal group (p=0.005). Conclusion: The incidence of atrial fibrillation was relatively more in patients with metal versus non-metal hip arthroplasty but there was no association of serum cobalt or chromium levels with incidence of atrial fibrillation in the subset of patients. In addition, all-cause mortality was significantly higher in the metal group suggesting potential toxic effects of metal containing hip arthroplasty.