Nickel release, a possible indicator for the duration of antiplatelet treatment, from a nickel cardiac device in vivo: a study in patients with atrial septal defects implanted with an Amplatzer occluder.

The present study was undertaken to evaluate the safety and release of nickel after implantation of a nickel device (Amplatzer occluder) in patients with an atrial septal defect (ASD) receiving antiplatelet therapy. Methods: Blood and urine samples were obtained from 24 patients with ASD before occluder implantation (baseline) and during a 12-month post closure period. Antiplatelet drugs were administered for the initial 6-month period post implantation. The nickel content in the specimens was determined using electrothermal atomic absorption spectroscopy. The clinical, sonographic and magnetic resonance imaging follow-ups were carried out 1 week, 1 month, 6 months and 12 months post implantation. Results: Mean baseline concentrations of nickel in serum and urine were within normal range with values of 0.6 ± 0.2 μg/l and 3.1 ± 1.2 μg/l, respectively. During the 6-week post closure period, the time needed for the formation of neointima on the surface of the graft, nickel levels in serum increased up to 5-fold (p < 0.01 versus baseline). Mean concentrations in serum and urine returned to baseline levels within 4 - 6 months post implantation. All patients showed satisfactory clinical improvements and there was no sonographic evidence of complications. Conclusions: The initial dissolution of nickel from the Amplatzer occluder is not a specific cardiovascular risk and is temporarily linked to the formation of the non-thrombogenic neointima on the surface of the graft. The antiplatelet drug regimen used (300 mg aspirin + 75 mg clopidogrel daily for 3 months in the initial phase and 100 mg aspirin daily for a further 3 months) appears to cover the period of neointima formation on the nickel device when nickel levels are significantly elevated. However, further studies in a larger number of patients and over a period greater than 12 months are needed to confirm the validity of these conclusions and to formulate definitive recommendations on the duration of the antiplatelet treatment.