Background: Light Transmission Aggregometry (LTA) is still the gold standard method for platelet function testing – to monitor dual antiplatelet therapy (DAPT) and to uncover platelet dysfunction. To achieve comparable results between different laboratories, recommendations for the standardization of LTA were published by different societies. New automated protocols allow to perform Gustav Born´s method on redesigned coagulation analyzers, reducing turn-around-time, and the amount of blood needed.

Aims: To make platelet function data compareable independently of the used method (routine coagulation analyzer versus optical aggregometer)

Methods: Platelet Rich Plasma (PRP) samples from 64 patients on DAPT or with bleeding disorders were tested. Routine LTA was performed on the Chronolog 700 aggregometer (Chrono-log Corporation; PRP volume 450µl) and compared with 2 Atellica COAG coagulation analyzers (Siemens Healthineers; PRP volume 140µl) using different stirring rates. LTA was performed using standard platelet activating reagents (i.e. ADP, Arachidonic Acid, Collagen, Epinephrine, TRAP, and Ristocetin) in PRP with normal platelet Counts. PRP was tested within 2 hours on all three devices.

Results: Interpretation of Aggregation results showed no significant differences
when using the same stirring rates but different agonist concentrations e.g. 2µg/ml Collagen (Horm) on the manual aggregometer, and 0,5µg/ml on the automated coagulation analyzer, respectively (Fig.1a).
Using the same agonist concentrations, corresponding interpretation was assured when using adopted stirring rates (automated analysis 600rpm (Fig 1b) versus manual method 1000rpm, (Fig. 1c).

Conclusions: Automated LTA on routine coagulation analyzers corresponds with the gold standard manual method and will allow for broad-based access in future patient care overcoming the limitations of the present manual method: 24/7/365 availability, standardized testing procedures, and minimized sample volumes.
However recommendations how to standardize LTA have to consider opto-physical differences (i.e. sample volume, stirring rate, wavelength) in the used analyzers in order to achieve reproducible results independent of the performing laboratory and platform.

[Comparison of automated and manual aggregation testing ]

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/improving-comparability-of-optical-aggregometry-results-from-automated-coagulation-analyzer-systems-compared-with-a-manual-aggregometer/