Ticagrelor With or Without Aspirin After PCI: The TWILIGHT Platelet Substudy

Area of Science:

• Cardiovascular Medicine
• Pharmacology
• Interventional Cardiology

Background:

• Percutaneous coronary intervention (PCI) strategies are evolving, with a trend towards withdrawing acetylsalicylic acid (ASA) while continuing P2Y12 inhibition.
• The impact of this strategy on blood thrombogenicity and platelet reactivity remains unclear.

Purpose of the Study:

• To compare the antithrombotic potency of ticagrelor monotherapy versus ticagrelor plus ASA in high-risk patients undergoing PCI with drug-eluting stents.
• To evaluate the pharmacodynamic effects of aspirin withdrawal on platelet reactivity and thrombogenicity.

Main Methods:

• Mechanistic substudy of the TWILIGHT trial involving patients randomized to ticagrelor plus placebo or ticagrelor plus ASA after 3 months of dual antiplatelet therapy.
• Ex vivo assays measured thrombus size and platelet reactivity to various stimuli (arachidonic acid, collagen, ADP, thrombin) at baseline and follow-up (1-6 months).
• Analysis of covariance was used to compare outcomes between groups.

Main Results:

• No significant difference in post-randomization thrombus size was observed between ticagrelor monotherapy and ticagrelor plus ASA groups.
• Platelet reactivity to arachidonic acid and collagen was significantly higher in the ticagrelor monotherapy group, indicating increased sensitivity to cyclooxygenase-1 blockade.
• Platelet reactivity to adenosine diphosphate and thrombin was similar between the groups.

Conclusions:

• Ticagrelor monotherapy demonstrates similar antithrombotic potency compared to ticagrelor plus ASA in high-risk PCI patients regarding ex vivo blood thrombogenicity.
• Withdrawal of aspirin leads to increased platelet reactivity markers sensitive to cyclooxygenase-1 blockade, suggesting a residual effect of aspirin inhibition.