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Platelet Activation in Coronary Artery Disease^*

Intracardiac vs Peripheral Venous Levels and the Effects of Angioplasty

^* From the Haemostasis, Thrombosis, and Vascular Biology Unit, University Department of Medicine, City Hospital, Birmingham, UK.

Correspondence to: Gregory Y.H. Lip, MD, City Hospital, Haemostasis, Thrombosis, and Vascular Biology Unit, Dudley Rd, Birmingham B18 7QH, UK: e-mail: g.y.h.lip{at}bham.ac.uk

Abstract

Background: Platelet activation and aggregation play a key role in coronary artery disease, with antiplatelet therapies leading to improved clinical outcomes. Limited data exist as to whether peripheral venous blood measurements of platelet physical indexes (eg, platelet count, volume, and granularity) and soluble markers of platelet activation (eg, P-selectin [sP-sel] and CD40 ligand [CD40L]) reflect the local (intracardiac) coronary environment. Furthermore, how percutaneous coronary interventions (PCIs) affect levels of peripheral/cardiac platelet indexes is unclear.

Methods: Blood samples were sequentially acquired from the coronary os, aortic root, coronary sinus, and the femoral vein, and where relevant, pre-PCI and post-PCI. Eighty-seven patients undergoing coronary angiography were recruited (mean [± SD] age, 59.8 ± 10.8 years; 54 men [62%]), of whom 36 proceeded to PCI. Platelet physical indexes and plasma sP-sel and CD40L levels were measured (by enzyme-linked immunosorbent assay).

Results: At baseline, no intracardiac vs peripheral differences were noted in sP sel levels, while CD40L levels were elevated in the aorta compared to the coronary sinus and femoral venous. The mean platelet count (MPC) was similar at all four sites, but within the coronary sinus blood, mean platelet volume (MPV) was significantly lower and mean platelet granularity (MPG) was higher when compared to arterial levels. Though aortic and femoral levels of sP-sel were raised following PCI, transcardiac gradients of plasma sP-sel levels were unaffected. PCI was associated with lower CD40L, MPC, and MPV levels but with a higher MPG level in all sampling sites.

Conclusions: sP-sel levels measured peripherally reflect the cardiac environment, unlike CD40L, MPC, MPV, and MPG. PCI leads to further platelet activation (raised sP-sel) despite aggressive antiplatelet therapy.

Key Words: cardiology • platelets • thrombosis