Dynamic Release and Clearance of Circulating Microparticles During Cardiac Stress
Rationale: Microparticles are cell-derived membrane vesicles, relevant to a range of biological responses and known to be elevated in cardiovascular disease.
Objective: To investigate microparticle release during cardiac stress and how this response differs in those with vascular disease.
Methods and Results: We measured a comprehensive panel of circulating cell-derived microparticles by a standardised flow cytometric protocol in 119 patients referred for stress echocardiography. Procoagulant, platelet, erythrocyte and endothelial, but not leucocyte, granulocyte or monocyte-derived microparticles were elevated immediately following a standardised dobutamine stress echocardiogram, and decreased after one hour. 25 patients developed stress-induced wall motion abnormalities suggestive of myocardial ischemia. They had similar baseline microparticle levels to those who did not develop ischaemia but, interestingly, their microparticle levels did not change during stress. Furthermore, no stress-induced increase was observed in those without inducible ischaemia but with a history of vascular disease. 14 patients subsequently underwent coronary angiography. A microparticle rise during stress echocardiography had occurred only in those with normal coronary arteries.
Conclusions: Procoagulant, platelet, erythrocyte and endothelial microparticles are released during cardiac stress and then clear from the circulation during the next hour. This stress-induced rise appears to be a normal physiological response that is diminished in those with vascular disease.
- Received June 3, 2013.
- Revision received October 16, 2013.
- Accepted October 18, 2013.