Sampling P2Y12 Receptor Inhibition With Prasugrel and Ticagrelor in Patients Submitted to Thrombolysis
Status:
Completed
Trial end date:
2014-10-01
Target enrollment:
Participant gender:
Summary
Introduction:
Platelet aggregation plays an important role in ischemic complications in patients undergoing
to percutaneous coronary intervention (PCI). The addition of clopidogrel, as a second
antiplatelet agent, to acetylsalicylic acid (ASA) was effective in reducing major
cardiovascular events in patients with acute coronary syndrome (ACS).
However, approximately 30% of ACS patients are resistant to clopidogrel, representing a
population of medically vulnerable and high risk for major cardiovascular events, including
myocardial infarction (MI), stent thrombosis and death.
In the randomized trial TRITON, prasugrel compared to clopidogrel was more effective in
significantly reducing the rates of MI (7.4% vs. 9.4%) and stent thrombosis (2.4% vs .1,1%)
in patients with ACS, however, patients treated with prasugrel showed higher rates of
bleeding (2.4 vs. 1.8%) and no difference in mortality. Upon analysis of subgroups is not
recommended its use in patients with a history of stroke in those older than 75 years and
weighing less than 60 kg.
The latest class of inhibitors of the P2Y12 receptor is the cyclopentyl-triazolopyrimidines
represented by ticagrelor. Unlike the thienopyridines, ticagrelor interacts with the platelet
receptors in a reversible way and has a beginning and peak of action faster.
The efficacy and safety of ticagrelor were evaluated in the study PLATO, where 18.624
patients with ACS were randomized to receive clopidogrel (75mg/day, with a loading dose of
300 to 600mg) or ticagrelor (90mg 2x/day with a loading dose of 180mg) The primary combined
endpoint (mortality from vascular causes, MI or stroke) at 12 months was significantly lower
in the ticagrelor (9.8% vs. 11.7%). There was no significant difference in the rates of major
bleeding in both groups. Moreover, the isolated analysis of the rates of MI, vascular
mortality and mortality from all causes showed statistically significant reduction in the
ticagrelor users. In this study, the main adverse effects were dyspnea and bradycardia.
The assessment of platelet reactivity may allow the individualization of antiplatelet
therapy. However, simply increasing the dose of clopidogrel in patients who persisted with
high platelet reactivity was not able to reduce the combined endpoint of cardiovascular
death, nonfatal myocardial infarction and stent thrombosis in six months.
In a population of patients with stable coronary artery disease, the substitution of
clopidogrel for ticagrelor showed a rapid and persistent decrease in platelet aggregation
measured by different laboratory methods. However, in patients with ACS subjected to PCI, the
assessment of platelet aggregation after the replacement of clopidogrel for prasugrel or
ticagrelor still requires evidence.
Objectives:
To evaluate the platelet response to ticagrelor and prasugrel in ACS patients with ST-segment
elevation submitted to thrombolysis.
To evaluate security in follow up of 30 days.
Methods:
The study will be a prospective, randomized, single-center (São Paulo Hospital - Federal
University of São Paulo), single-blind. The investigators will select 50 patients admitted
with ACS with ST-segment elevation submitted to thrombolysis and who underwent cardiac
catheterization between 3 to 24 hours in the case of reperfusion or immediately for rescue
angioplasty. Blood sample for analysis of platelet aggregation through the system VerifyNow
®, shall be obtained immediately after the procedure on patients on clopidogrel for at least
seven days in maintenance dose of 75mg or after 8 to 6 hours after the dose of 300mg and
600mg respectively. Patients will be randomized in a 1:1 ratio to receive ticagrelor the dose
of 180mg and maintained dose of 90 mg twice a day for thirty days or prasugrel dose of 60mg
and maintained for thirty days at a daily dose of 10mg. A new blood sample and analysis of
platelet aggregation will be repeated after 2, 6 and 24 hours. The demographic and clinical
data of this population will be collected in specific form and stored in databases for later
analysis