Background Microparticles (MP) are sub-micron vesicles shed from eukaryotic cells following activation or apoptosis. They appear to have a role in the genesis and progression of atherosclerosis, leading to symptomatic coronary artery disease (CAD). It is now established that the levels of MP are elevated in CAD however, the MP signature associated with the spectrum of CAD is yet to be established.

Methods 42 patients undergoing PCI (11 STEMI, 13 NSTEMI and 18 stable angina) were prospectively enrolled. MP levels from venous blood taken prior to PCI were measured by flow cytometry.

Results (Figure 1): Patients with STEMI expressed significantly higher levels of CD62P+ platelet-derived MP (median 14.5%, IQR 8.1–20.3%) compared to NSTEMI (median 1.2%, IQR 0.4–19%, p < 0.001) and stable angina (median 1.1%, IQR 0.5–2.0%, p < 0.001). Patients in the STEMI group also expressed higher levels of CD62E+ (E-selectin) endothelial cell-derived and CD66B+ neutrophil-derived MP. The NSTEMI group expressed higher CD54⁺ (ICAM-1) endothelial cell-derived MP.

Conclusions The MP signature associated with CAD appears to differ with STEMI showing a predominantly pro-thrombotic signal and NSTEMI a pro-inflammatory signal. This suggests not only differing underlying pathophysiology but also indicated a potential new tool in rapid assessment and risk stratification.

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Abstract 14 Figure 1

Microparticle sub-populations (expressed as percentage of total Annexin positive microparticles)