Table 1.
Succinct description of the main platelet function tests used for the in vitro evaluation of the effects of antiplatelet therapy; adapted from [33], with permission.
| Platelet Function Test | Principle and Interpretation |
|---|---|
| Conventional photometric aggregation | Changes in light transmission in platelet-rich plasma. Activators: arachidonic acid for aspirin, ADP for P2Y12 inhibitors, or another activator (collagen, TRAP) that more or less uses activation amplification (thromboxane A2 and ADP). |
| Serum thromboxane B2 | Coagulation of whole blood at 37 ℃ and measurement of thromboxane B2 (a stable metabolite of thromboxane A2) in the serum obtained. Close evaluation of the aspirin target (COX-1), but it can also be diminished by an NSAID other than aspirin or poor blood coagulation. |
| VASP assay | ADP-induced inhibition, via its interaction with the P2Y12 receptor, of the elevation of intra-platelet levels of cAMP (a secondary messenger inhibiting platelet activation) induced by PGE1 (platelet activation inhibitor); then, detection by quantification of the degree of phosphorylation of the VASP protein, using flow cytometry or ELISA. A whole blood test that specifically evaluates the ADP P2Y12 receptor’s inhibitors. |
| VerifyNow® | Automated measurement, in whole blood, of the consequence of the interaction between fibrinogen and activated GP IIb/IIIa complex (artificial microbeads covered with fibrinogen). Dedicated cartridges for treatment using aspirin, P2Y12, or anti-GPIIb/IIIa inhibitors. |
| Impedance aggregometry | Whole blood (diluted), two devices: Multiplate® and ROTEM® platelet.Multiplate® is a multiple electrode impedance platelet aggregometer with five channels and computer-assisted control. Platelet activators to evaluate the effects of aspirin or of P2Y12 inhibitors (arachidonic acid and ADP, respectively). ROTEM® platelet is a new module of the ROTEM® device dedicated to platelet function. |
| PFA® | PFA-100® (now PFA-200®); whole blood under flow, with (very) high shear stress. A platelet plug occludes an orifice in a membrane soaked with either collagen and ADP or collagen and epinephrine. Sensitive to aspirin when using a collagen and epinephrine cartridge, but not very sensitive to P2Y12 inhibitors; there is a sensitized cartridge dedicated to P2Y12 inhibitors (INNOVANCE® PFA P2Y). |
| TEG® PlateletMapping™ | Gradual modification of the viscoelastic properties of whole blood, along with its coagulation and clot organization (its mechanical properties). Sensitized evaluation of platelet involvement in maximal amplitude. |
Some tests that have only been used in particular studies and are not widely available have not been included in this table. It is important to note that activator concentrations can differ from one test to another. ADP: adenosine diphosphate; cAMP: cyclic adenosine monophosphate; COX: cyclooxygenase; ELISA: enzyme-linked immunosorbent assay; GP: glycoprotein; NSAID: non-steroidal anti-inflammatory agent; PFA: Platelet Function Analyzer; PGE: prostaglandin E; ROTEM: rotational elastometry; TEG: Thromboelastograph; TRAP: thrombin receptor-activating peptide. VASP: vasodilator-stimulated phosphoprotein.