Selective and rapid monitoring of dual platelet inhibition by aspirin and P2Y12 antagonists by using multiple electrode aggregometry.

Background Poor platelet inhibition by aspirin or clopidogrel has
been associated with adverse outcomes in patients with
cardiovascular diseases. A reliable and facile assay to measure
platelet inhibition after treatment with aspirin and a P2Y12
antagonist is lacking. Multiple electrode aggregometry (MEA), which
is being increasingly used in clinical studies, is sensitive to
platelet inhibition by aspirin and clopidogrel, but a critical
evaluation of MEA monitoring of dual anti-platelet therapy with
aspirin and P2Y12 antagonists is missing. Design and Methods By
performing in vitro and ex vivo experiments, we evaluated in
healthy subjects the feasibility of using MEA to monitor platelet
inhibition of P2Y12 antagonists (clopidogrel in vivo, cangrelor in
vitro) and aspirin (100 mg per day in vivo, and 1 mM or 5.4 mM in
vitro) alone, and in combination. Statistical analyses were
performed by the Mann-Whitney rank sum test, student' t-test,
analysis of variance followed by the Holm-Sidak test, where
appropriate. Results ADP-induced platelet aggregation in
hirudin-anticoagulated blood was inhibited by 99.3 ± 1.4% by in
vitro addition of cangrelor (100 nM; p < 0.001) and by 64 ± 35%
by oral clopidogrel (600 mg) intake (p < 0.05; values are means
± SD). Pre-incubation of blood with aspirin (1 mM) or oral aspirin
intake (100 mg/day for 1 week) inhibited arachidonic acid
(AA)-stimulated aggregation >95% and 100 ± 3.2%, respectively (p
< 0.01). Aspirin did not influence ADP-induced platelet
aggregation, either in vitro or ex vivo. Oral intake of clopidogrel
did not significantly reduce AA-induced aggregation, but P2Y12
blockade by cangrelor (100 nM) in vitro diminished AA-stimulated
aggregation by 53 ± 26% (p < 0.01). A feasibility study in
healthy volunteers showed that dual anti-platelet drug intake
(aspirin and clopidogrel) could be selectively monitored by MEA.
Conclusions Selective platelet inhibition by aspirin and P2Y12
antagonists alone and in combination can be rapidly measured by
MEA. We suggest that dual anti-platelet therapy with these two
types of anti-platelet drugs can be optimized individually by
measuring platelet responsiveness to ADP and AA with MEA before and
after drug intake.