Diurnal Variability of On-Treatment Platelet Reactivity in Clopidogrel versus Prasugrel Treated Acute Coronary Syndrome Patients: A Pre-Specified TROPICAL-ACS Sub-Study.

Long-term evidence supports a clustering of cardiovascular events in the early morning and smaller mechanistic studies in aspirin-treated patients have shown increased platelet reactivity at the end of the dosing interval. Comparative pharmacodynamic analyses for different adenosine diphosphate (ADP) receptor inhibitors in percutaneous coronary intervention-treated acute coronary syndrome (ACS) patients are lacking and this pre-specified analysis from the randomized Testing Responsiveness To Platelet Inhibition On Chronic Antiplatelet Treatment For Acute Coronary Syndromes (TROPICAL-ACS) trial aimed for the first time at investigating diurnal variability of on-treatment platelet reactivity in clopidogrel versus prasugrel treated patients. TROPICAL-ACS randomized 2,610 ACS patients to either treatment with prasugrel (control group) or to a platelet function testing-guided de-escalation of anti-platelet treatment with a switch to clopidogrel (guided de-escalation group).