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Ticagrelor has been demonstrated to provide a more rapid and more powerful inhibition of platelet aggregation compared with clopidogrel in coronary artery disease (CAD) patients. However, current guidelines recommend ticagrelor 90 mg twice daily might not be suitable for patients of Chinese. Therefore, the investigators performed this study to observe the efficacy of 60-mg ticagrelor in comparison to 75-mg clopidogrel in Chinese patients with stable CAD.
The study sought to observe the effects of optimal dose of ticagrelor（90 mg qd）ticagrelor and double standard-dose clopidogrel on platelet reactivity in coronary heart disease patients with high on-treatment platelet reactivity (HTPR) while on clopidogrel. HTPR with clopidogrel administration in coronary heart disease (CHD) patients has associated with an increased risk of adverse events. Newer P2Y12 inhibitors ticagrelor (90mg BID) provide stronger platelet inhibition compared with clopidogrel, but a low-dose of ticagrelor (90mg QD) has not been previously studied in Chinese CHD patients with HTPR.
Platelet function testing has been considered for DAPT strategy adjustments to reduce the patient's risk of ischemia and bleeding. Although several previous RCT studies did not find any benefit in the detection of platelet function， the previous studies were mostly low-risk populations, and the P2Y12 receptor antagonists were simply clopidogrel, and the detection methods were relatively simple. Therefore, the need for platelet monitoring in high-risk ACS patients receiving new potent P2Y12 inhibitor ticagrelor, as well as the diagnostic threshold for different platelet function assays needs further study. In addition, due to the differences on the response to anti-platelet drugs between the East and the West, it is not appropriate to simply refer to the conclusion of the other party. However, as of now, there is no large sample randomized controlled study systematically focused on the applicability and status of platelet function tests in East Asian populations, especially Chinese populations.
to assess whether cessation of 12 months DAPT regimen containing Ticagrelor results in a hyperreactive phase of platelet function
In the PLATO substudy referring to patients presenting with an ST-elevation Myocardial Infarction(STEMI), out of the 4201 who received ticagrelor, 1326 had been pre-treated with a 600mg clopidogrel loading dose (LD) within 24 hours prior to randomization. It is a logical assumption, that patients who are being reloaded with ticagrelor will demonstrate reduced platelet reactivity (PR) at 24 hours, in comparison to those who were initially loaded with ticagrelor, due to the synergistic antiplatelet effect. Single loading with ticagrelor though, will possibly be accompanied by a smaller bleeding potency compared to reloading with ticagrelor. Therefore, we assume that single loading with ticagrelor is non-inferior to reloading with ticagrelor, in terms of platelet reactivity. P2Y12 inhibitor naive patients with STEMI, they will be randomized immediately after coronary angiography (Hour 0) in receiving either Ticagrelor 180mg LD or Clopidogrel 600mg LD and 2 hours later reloading with Ticagrelor 180mg, after written informed consent. PR will be measured, using the VerifyNow assay at randomization (Hour 0) and at 2, 4, 6 and 24 hours post randomization. In addition, a 12-lead ECG will be performed before randomization, 90 and 180 minutes after the first balloon inflation, as well as on the exit day. Troponin I and CK-MB will be assessed at randomization and at hour 4, 12, 24, 48 and 72 after randomization. Non inferiority of Ticagrelor LD versus Ticagrelor re-LD would be accepted if the upper bound of the 2-sided 95% CI around the estimated LS mean difference (Ticagrelor LD minus Ticagrelor re-LD) in the primary end point (PR at 24 hours) would lie bellow Δ=35 PRU. This non-inferiority margin (Δ) represents the upper bound of the LS mean difference in PR between Ticagrelor and Prasugrel arm at 24 hours after LD in a pharmacodynamic study of 55 STEMI patients. Considering previous studies PR at 24 hours post randomization was estimated at 47±40 PRU and 41±35 PRU for Ticagrelor only LD and Ticagrelor re-LD group respectively. To obtain 85% statistical power with a 2-sided alpha=0.05, approximately 32 patients in each treatment group (64 in total) would be needed to establish the primary hypothesis using the abovementioned non-inferiority margin of 35 PRU. Anticipating a 5% dropout rate, enrollment was set to at least 68 patients. The primary endpoint, as well as PR at all the other time points of the study will be analyzed separately via a mixed effect model with treatment as fixed effect, patient as a random intercept and PR at baseline as a covariate. Least squares estimates of the mean difference will be presented, with 95% confidence intervals and a two-sided p-value for the treatment effect. P values for secondary endpoints will be reported for two-tailed tests of superiority.
This is a prospective, multi-center, non-randomized, controlled study in 2 sequential groups of P2Y12 inhibitor-naive consecutive STEMI patients undergoing primary PCI. Following aspirin 325 mg LD, patients will receive 60 mg or 100 mg of prasugrel, respectively. Platelet reactivity (PR)will be assessed at Hour 0 (before prasugrel's administration immediately prior to PCI) and at Hours 0.5, 1, 2, 4 thereafter. Platelet function testing (in PRU) will be performed with the VerifyNow (Accumetrics Inc., San Diego, CA, USA) P2Y12 function assay.
Clopidogrel administration is commonly prescribed in patients undergoing percutaneous coronary intervention, in patients with previous stroke and in patients under chronic hemodialysis via fistulae. Patients with chronic renal failure present lower clopidogrel response compared to those with normal renal function. Ticagrelor is a new oral direct-acting antagonist, which provides greater platelet inhibition in both clopidogrel responders and non-responders. It has also been shown that in patients with chronic kidney disease (creatinine clearance <60 mL/min)ticagrelor achieved an absolute risk reduction of cardiovascular death, myocardial infarction, and stroke greater than that of patients with normal renal function. Clopidogrel resistant patients as assessed by VerifyNow P2Y12(Accumetrics)will be administered after informed consent ticagrelor 90 mg twice daily for 15 days. Platelet reactivity will be determined at the end of the treatment period. Bleeding events, major adverse cardiac events and any side effects until Day 15 will be reported in a descriptive manner.
This is a single-center, randomized, single-blind, investigator-initiated, pharmacodynamic study with a parallel design. Patients with ST elevation myocardial infarction, undergoing primary percutaneous coronary intervention will be randomized after informed consent, in a 1:1 ratio to the following treatment groups: Group Α: Ticagrelor 180mg loading dose (LD), followed by a 90mg x2 maintenance dose (MD)starting 12±6 hours post LD, until Day 5 (5 days after randomization) Group Β: Prasugrel 60 mg LD followed by 10mg x1 MD starting 24 hours post LD, until Day 5 (5 days after randomization). Platelet reactivity assessment will be performed at randomization (Hour 0) and at 1, 2, 6, 24 hours after randomization, and on Day 5. Documentation of major adverse cardiac events (death, myocardial infarction, stroke, revascularization procedure with PCI or CABG)and serious adverse events (bleeding, other adverse events)will be performed until Day 5.
The use of dual antiplatelet therapy is considered standard of care in patients post percutaneous coronary intervention (PCI) with stenting. However, a significant proportion of patients is considered clopidogrel resistant and this resistance is shown to be accompanied by future adverse events. The aim of the study is to define in consecutive patients with acute coronary syndrome (ACS) undergoing PCI, those aged>75years and/or weighted<60 Kg with high on-clopidogrel platelet reactivity (Platelet Reactivity Units-PRU≥235) as estimated 24 hours post PCI with the VerifyNow assay. Those patients will be randomized after informed concent in 1:1 fashion to prasugrel 5 mg or clopidogrel 150mg daily. Platelet reactivity will be assessed at day 15 and then treatment crossover will be performed. At day 30 platelet reactivity will be determined as well.
The PHP study aims to delineate gene products involved in high on-treatment platelet reactivity in aspirin-treated cardiovascular patients.