Point-of-Care Testing of Hemostasis in Cardiac Surgery

An excessive perioperative blood loss, that requires transfusion of blood products, sometimes occurs in patients undergoing cardiopulmonary bypass for cardiac surgery. Blood loss and transfusion requirements in these patients may be reduced with a better control of heparin treatment and its reversal. Blood component administration in patients with excessive post-cardiopulmonary bypass bleeding has been empiric for a long time due to turnaround times of laboratory coagulation tests. Devices are now available for rapid, point-of-care assessment of hemostasis alterations to allow an appropriate, targeted therapy. In particular, a quick evaluation of platelet and coagulation defects with new point-of-care devices can optimize the administration of pharmacological and transfusion-based therapy in patients with excessive bleeding after cardiopulmonary bypass

Platelet Function tests: A Comparative Review

In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation – adhesion, shape change, release reaction, and aggregation – have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT) dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]). POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well-tried and innovative platelet function tests and their methodological features and clinical applications are considered

Non-traumatic splenic rupture on dual antiplatelet therapy with aspirin and ticagrelor after stenting for acute coronary syndrome

AbstractWe report a case of non-traumatic splenic rupture in a 57-year-old man on dual antiplatelet therapy (DAPT) with aspirin and ticagrelor, seven months after percutaneous coronary intervention and drug-eluting stent implantation for non-ST elevation myocardial infarction. No splenic abnormalities were found at histopathological analysis after splenectomy, and no history of recent trauma was reported. Once restarted, DAPT after splenectomy, assessment of platelet function was performed by light transmittance aggregometry, showing a profound inhibition of platelet function by adenosine diphosphate, arachidonic acid, and collagen. Taking into account the bleeding risk associated with low on-treatment platelet reactivity, and to switch the patient from ticagrelor to a less potent P2Y12 inhibitor such as clopidogrel, cytochrome P450, genetic polymorphisms accounting for clopidogrel response variability were analyzed. The polymorphisms associated with lower response (CYP2C19*2, CYP2C19*3) were absent. Therefore, ticagrelor was withdrawn, and DAPT was continued with aspirin and clopidogrel. Rupture of the spleen may occur in the absence of major trauma or previous splenic diseases, and could be a complication of antithrombotic treatments. Moreover, low on-treatment platelet reactivity during DAPT is emerging as a possible risk factor for bleeding complications, so underlining the usefulness of assessing platelet function in special conditions to ensure that the patient receives the best tailored antiplatelet therapy.<Learning objective: Non-traumatic splenic rupture is a rare event, and is more often associated with pre-existing splenic abnormalities. However, it may be also a complication of medical treatments, especially with antithrombotic drugs. Low on-treatment platelet reactivity is emerging as a possible risk factor for bleeding complications; therefore, assessing platelet function in special conditions could be useful to ensure the patient receives the best-tailored antiplatelet therapy.