Platelet deposition in remote cardiac regions after coronary occlusion.
BACKGROUND
Activated platelets might contribute to endothelial dysfunction in non-ischaemic territories during acute myocardial infarction. We assessed platelet deposition, coronary flow reserve and contractile function in remote cardiac regions after transient coronary occlusion and their association with systemic platelet activation.


METHODS
In 10 pigs (series A) subjected to 48-min occlusion of the left anterior descending coronary artery (LAD), 99mTc-platelet content in the right coronary artery (RCA) and its dependent myocardium was counted after reflow. In 10 pigs (series B) receiving the same occlusion of the RCA, the hyperaemic response at the LAD and systolic shortening in LAD-dependent myocardium were monitored after reperfusion. P-selectin expression on circulating platelets was assessed in both series by flow cytometry.


RESULTS
In series A, platelet counts in the RCA and non-ischaemic myocardium were correlated with platelet content, polymorphonuclear leukocyte infiltration and infarct size in the reperfused zone, as well as with the percentage of P-selectin-positive platelets after reflow. In series B, a transient reduction in peak hyperaemic response in the LAD and sustained contractile dysfunction in non-ischemic myocardium were observed after releasing the RCA occlusion, these changes being also correlated with platelet activation status.


CONCLUSIONS
Ischaemic injury triggers macro- and microvascular platelet deposition and causes an impairment in coronary flow reserve and contractile function in distant regions of the heart, which are related to activation of circulating platelets.
Barrabés
J A
JA
Servicio de Cardiología, Hospital Universitari Vall d'Hebron, Barcelona, Spain.
Mirabet
M
M
Agulló
L
L
Figueras
J
J
Pizcueta
P
P
Garcia-Dorado
D
D
D000818:Animals; D003326:Coronary Circulation; D054059:Coronary Occlusion / Q000097:blood*; D003331:Coronary Vessels / Q000503:physiopathology*; D006321:Heart / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D015428:Myocardial Reperfusion Injury / Q000097:blood; D019007:P-Selectin / Q000378:metabolism; D015539:Platelet Activation; D010976:Platelet Count; D013552:Swine
D019007:P-Selectin