Light transmission aggregometry (LTA)

Platelet‐rich plasma (PRP) and autologous platelet‐poor plasma (PPP) were obtained by centrifugations of citrated blood as recommended.²³ A photometric method on an 8‐channel aggregometer (PAP‐8E, Bio/Data Corporation, Horsham, PA, USA) was used.

Platelet‐rich plasma was incubated 2 minutes at 37°C and was then stirred at 122 g for 2 minutes before adding saline, ADP or AA (5 μmol L⁻¹ and 1 mmol L⁻¹, respectively). The platelet response was recorded during 5 minutes. Platelet aggregation was quantified as the percentage of maximal optical change.

In the last version of the BH's guidelines, when ADP‐induced platelet aggregation is <50%, no dose change of dipyridamole is required; when AA‐induced platelet aggregation is <30%, no dose change of aspirin is required.