The relationship between plasma MMP-1,-7,-8 and-13 levels and embolic potential during carotid endoluminal intervention

Background. Patients undergoing carotid endoluminal intervention are at risk of embolic stroke even with the use of distal protection devices. Matrix metalloproteinases (MMPs) have been implicated as a causal factor in plaque instability leading to spontaneous embolisation. We investigated whether plasma MMP levels correlated with the embolisation during carotid endoluminal intervention. Methods. Thirty circumferentially intact carotid endarterectomy specimens were subjected to a standardised angioplasty procedure in a pulsatile ex vivo model. Emboli collected in a series of distal filters were counted and sized. Plasma samples were collected pre-operatively and analysed for MMP-7 and MMP-8 levels using Western immunoblotting. MMP-1 and MMP-13 levels were determined using ELISA. Emboli number and maximum size were correlated with plasma levels of the MMPs using Spearmans rank. Results. Total MMP-8 levels were related to maximum embolus size (r = 0.442, p = 0.005) but not emboli number (r 0.342, p = 0.052). MMP-1, -7 and -13 were not correlated with either emboli number or with maximum embolus size. Conclusion. Pre-operativc plasma MMP-8 levels are related to the size of embolifrom plaques during carotid endovascular intervention. Further in vivo studies need to be performed to assess the importance of this finding. There is potential for development of plasma markers to identify those patients at greater risk of embolic stroke during carotid endoluminal intervention.