Circulating endothelial microparticles in patients with acute myocardial infarction

Circulating endothelial microparticles (EMPs), the small vesicles released from altered endothelial cells, have been established as markers of endothelial injury. The elevated count of EMPs has been described in different conditions involving endothelial injury, including acute myocardial infarction (AMI).

To assess the presence of EMP in patients with acute MI in relation to early clinical outcome and coronary angiography results.

EMPs counts were determined in 66 patients pts (23 women, 43 men) with documented ST elevation AMI and in 10 control patients with no evidence of coronary artery disease. All pts with AMI underwent coronary angiography with attempted primary angioplasty. EMPs were assayed by flow cytometry in platelet-poor plasma with combinations of fluorescent antibodies (anti CD31, -51, -42) allowing distinction of EMPs from platelet microparticles. Clinical and angiography results were compared with EMP levels.

Three kinds of EMPs were measured: CD31+, CD51+ and CD31+/51+. The percentage of EMPs CD31+/CD51 was significantly (p=0,042) higher in patients with AMI in comparison with control subjects. However, a marker, which distinguished both groups the most, was the level of EMPs CD51+. It was significantly (p=0,024) higher in pts with AMI than in control pts. The levels of CD31+ were similar in both groups. There was no correlation between EMP levels, clinical and angiography results.

The presence of circulating EMPs provides direct evidence of endothelial injury in AMI. The clinical and practical value of these results, however, needs further exploration.