Plasma MMP-9 – a Marker of Carotid Plaque Instability☆

Objectives: to investigate whether peripheral blood levels of matrix metalloproteinases (MMPs) or their inhibitors are altered in patients with particulate cerebral embolisation. Design: a prospective study. Materials and methods: using sandwich enzyme immunoassay, plasma levels of MMPs-1, -2, -3 and -9, plus TIMPs1 and -2 were quantified in 70 consecutive patients undergoing carotid endarterectomy. Patients were monitored with transcranial Doppler (TCD) preoperatively and during the dissection phase of the operation to detect those with spontaneous particulate embolisation (n=21). Results: the plasma level of MMP-9 was significantly higher in those patients with evidence of spontaneous embolisation compared to those without. There were no differences in other MMP levels, or plasma concentrations of TIMPs. Conclusions: plasma MMP-9 levels are elevated in patients with particulate cerebral embolisation, and this may represent a novel marker of atherosclerotic plaque instability.