Plasma MMP-9 - a marker of carotid plaque instability

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