Affiliations: Department of Cardiothoracic – Vascular Anesthesia and Intensive Care, Department of Vascular Surgery, IRCCS Policlinico San Donato, Milan, Italy
Correspondence:
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Corresponding author: Marco Ranucci, MD, FESC, Director of Clinical Research in the Department of Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Milan, Italy. Tel.: +39 02 52774320; Fax: +39 02 55602262; E-mail: cardioanestesia@virgilio.it.
Abstract: BACKGROUND:Platelet reactivity changes with shear stress, which in turn depends on whole blood and plasma viscosity (PV). Platelets interact with fibrinogen during thrombus formation, and fibrinogen is a determinant of PV. The respective role of PV and fibrinogen on platelet function is still unclear. METHODS:30 patients undergoing vascular surgery were admitted to this study. In each patient we measured PV using a cone-on-plate viscosimeter, functional fibrinogen using thromboelastometry, and platelet reactivity to thrombin receptor activating peptide (TRAP) stimulation using multi-electrode aggregometry. Routine coagulation parameter were measured. RESULTS:At the univariate analysis, platelet reactivity was positively associated with mean platelet volume (R2 = 0.15, P = 0.033) and PV (R2 = 0.35, P = 0.0006), and negatively associated with serum bilirubin (R2 = 0.20, P = 0.013) and international normalized ratio (INR) (R2 = 0.19, P = 0.017). At the multivariable analysis, only PV (P = 0.001) and INR (P = 0.019) remained independent predictors of platelet reactivity. CONCLUSION:PV is directly and independently associated with platelet reactivity, whereas functional fibrinogen is not. Aspirin treatment is inadequate to correct thrombin-induced platelet aggregation. In presence of hyperviscosity, patients at high cardiovascular risk, may benefit from more aggressive anti-platelet treatments.
