VerifyNow (Accumetrics) is a point-of-care platelet aggregometer that uses single-use test cartridges. Each cartridge contains fibrinogen-coated beads, platelet agonist, preservative, and buffer. The patient sample is 3.2% citrated whole blood, which is automatically dispensed from the blood collection tube into the assay device by the instrument; no blood handling is required by the user. The instrument controls assay sequencing, establishes the assay temperature, controls the reagent sample mixing for the required duration, determines the degree of platelet function, displays the results and status information to the user, and performs self-diagnostics. The quality control (QC) system includes an electronic QC, an assay device internal control, and two levels of external, wet controls.
The VerifyNow Aspirin test is an optical method that utilizes arachidonic acid as the agonist to activate platelets. Agonist-induced platelet aggregation is enhanced by the use of fibrinogen-coated beads and measured as an increase in light transmission. The instrument automatically calculates the results and expresses them as aspirin reaction units. A cut-off value is used to determine whether a patient has a sub-optimal response to aspirin therapy.