UNASSIGNED: Dual antiplatelet therapy is standard for patients undergoing percutaneous coronary intervention (PCI) with stents. Traditionally, patients swallow the loading dose of a P2Y12 inhibitor before or during PCI. Time to achieve adequate platelet inhibition after swallowing the loading dose varies significantly. Chewed tablets may allow more rapid inhibition of platelet aggregation. However, data for this strategy in patients with stable ischemic heart disease or non-ST-elevation acute coronary syndrome (NSTE-ACS) are less robust.
UNASSIGNED: In this single-center prospective trial, 112 P2Y12-naïve patients with stable ischemic heart disease or NSTE-ACS on aspirin therapy and who received ticagrelor after coronary angiography but before PCI were randomized to chewing (n=55) or swallowing (n=57) the ticagrelor loading dose (180 mg). Baseline variables were compared using 2-sample t-test and chi-squared/Fisher\'s exact tests as appropriate, with alpha set at 0.05. P2Y12 reaction units (PRU) were compared at baseline, 1 hour, and 4 hours using Wilcoxon rank-sum test. Patients then received standard ticagrelor dosing.
UNASSIGNED: After exclusions, P2Y12 PRU in the chewed and swallowed groups at baseline, 1 hour, and 4 hours after ticagrelor loading dose were 243 vs 256 (P=0.75), 143 vs 210 (P=0.09), and 28 vs 25 (P=0.89), respectively. No differences were found in major adverse cardiac events (MACE) or major bleeding at 30 days and 1 year.
UNASSIGNED: In patients with stable ischemic heart disease or NSTE-ACS, chewing rather than swallowing ticagrelor may lead to slightly faster inhibition of platelet aggregation at 1 hour with no increase in MACE or major bleeding.

OBJECTIVE: To investigate the associations of perioperative P2Y12 reaction units (PRU) measured using VerifyNow with ischemic and bleeding events, and to determine the PRU threshold in the setting of elective neuro-endovascular treatment (EVT) for intracranial/extracranial vascular disease in patients taking aspirin and clopidogrel.
METHODS: Of the patients undergoing elective neuro-EVT while taking aspirin and clopidogrel, those taking both antiplatelet agents for 7 days or more and whose PRU and aspirin reaction units (ARU) were measured were included. The primary and safety outcomes were defined as symptomatic ischemic and major bleeding events within 30 days after EVT.
RESULTS: A total of 197 patients were available for the analyses. Higher PRU was associated with symptomatic ischemic events on multivariable logistic analysis (odds ratio per 10 increase 1.14 [95% confidence interval 1.03-1.27], p=0.011). Receiver operating characteristic curve analysis showed that PRU ≥212 was the threshold to predict symptomatic ischemic events (area under the curve=0.73; sensitivity, 62.5%; specificity, 82.0%). Lower PRU was also associated with major bleeding events (odds ratio per 10 increase 0.87 [0.78-0.96], p=0.004), and the threshold to predict major bleeding events was PRU ≤46 (area under the curve=0.76; sensitivity, 70.0%; specificity, 87.2%) CONCLUSIONS: The PRU value was associated with symptomatic ischemic and major bleeding events after elective neuro-EVT in patients taking aspirin and clopidogrel. PRU ≥212 and PRU ≤46 appeared to be the threshold values to predict symptomatic ischemic and major bleeding events, respectively.

BACKGROUND: Thrombin is the most potent platelet activator, and achieves rapid platelet activation even in the presence of antiplatelet therapy. Since activated platelets respond stronger to additional stimuli, the extent of endogenous thrombin generation may in part be responsible for the reported response variability to aspirin and clopidogrel therapy.
METHODS: Thrombin generation potential was measured with a commercially available assay, and platelet reactivity was assessed with the vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay, light transmission aggregometry (LTA), the VerifyNow aspirin and P2Y12 assays, and multiple electrode aggregometry (MEA) in 316 patients on dual antiplatelet therapy undergoing angioplasty and stenting.
RESULTS: Peak thrombin, the lag phase and the area under the curve of thrombin generation correlated poorly with on-treatment platelet reactivity by all test systems. High on-treatment residual platelet reactivity (HRPR) in response to arachidonic acid was seen in 33 (10.5%), 41 (13%), and 79 (25.7%) patients by LTA, the VerifyNow aspirin assay, and MEA, respectively. HRPR in response to adenosine diphosphate was seen in 150 (48.1%), 48 (15.3%), 106 (33.7%), and 118 (38.3%) patients by the VASP assay, LTA, the VerifyNow P2Y12 assay, and MEA, respectively. Peak thrombin generation did not differ between patients without and with HRPR by the VASP assay, LTA, the VerifyNow P2Y12 assay and MEA. In the VerifyNow aspirin assay, patients without HRPR had higher peak thrombin generation than patients with HRPR (p=0.01). Finally, patients without and with high peak thrombin generation exhibited similar on-treatment platelet reactivity by all test systems, and high peak thrombin generation occurred to a similar extent in patients without and with HRPR.
CONCLUSIONS: Response to antiplatelet therapy with aspirin and clopidogrel is not associated with thrombin generation potential.