Effect of Prasugrel Versus Clopidogrel on Platelet Function After Bivalirudin Cessation

The Effect of Prasugrel as Compared to Clopidogrel on Platelet Function Immediately Following the Termination of Intravenous Bivalirudin in Patients Undergoing Percutaneous Coronary and Structural Cardiac Intervention

Early stent thrombosis has been noted with increased frequency in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) who are treated with bivalirudin and clopidogrel. The brief half life of bivalirudin acting in concert with the delayed action of clopidogrel likely exposes patients to thrombosis during a vulnerable period of reduced antiplatelet effect in the immediate post stenting period. Combination therapy with bivalirudin and prasugrel is conceptually attractive as the more rapid onset of action of prasugrel could potentially significantly diminish the vulnerable period, likely reducing the potential for acute stent thrombosis. The trials which have documented the efficacy of prasugrel as compared to clopidogrel have, in general, not reported on patients in whom bivalirudin was utilized. Currently, in the United States, bivalirudin is the most commonly used adjunctive agent used during PCI. Using light transmission aggregometry, this study will examine the inhibition of platelet aggregation in patients randomized to treatment with clopidogrel vs prasugrel during the vulnerable period following the discontinuation of bivalirudin therapy. The investigators anticipate that this study will document significant enhancement of inhibition of platelet aggregation in patients randomized to prasugrel treatment.

Study Overview

• Status: Completed
• Conditions: Coronary Artery Disease
• Intervention / Treatment: Drug: Prasugrel; Drug: Clopidogrel

Detailed Description

Percutaneous coronary intervention (PCI) targeting coronary lesions in patients with coronary syndromes leads to iatrogenic endothelial disruption and heightened platelet activation and aggregation. Blocking platelet aggregation with glycoprotein (GP) IIb/IIIa inhibitors has been demonstrated to be of unequivocal benefit when combined with heparin in patients undergoing PCI. Heparin-mediated thrombin inhibition is an established therapy for safely performing PCI, however, there are several well known limitations of heparin including its variable anticoagulant effect due to nonlinear pharmacokinetics and inconsistent binding to blood proteins. In addition, heparin does not effectively block clot-bound thrombin and may cause thrombocytopenia.

The direct thrombin inhibitor (DTI), bivalirudin, which binds with high affinity to exosite I of thrombin, may be a safer alternative to other commonly used pharmacologic PCI adjuncts with an expert consensus document defining it as "reasonable to use as an alternative to unfractionated heparin and GP IIb/IIIa antagonists in low-risk patients undergoing elective PCI". The ACUITY trial has supported the use of bivalirudin in patients with unstable coronary syndromes. This study showed similar rates of ischemic events and less bleeding when compared with patients treated with heparin and GP IIb/IIIa inhibitors. Similar results were reported in the REPLACE-2 randomized trial, which studied a patient population with a lower prevalence of acute coronary syndromes. Recent results from our laboratory suggest that at least a part of the salutary effects of DTIs are due to a reduction of thrombin and to a lesser extent, collagen-mediated platelet activation.

Inhibition of the platelet P2Y12 Adenosine Diphosphate (ADP) receptor is standard of care when added to aspirin in patients undergoing coronary stenting. A 600 mg loading dose of clopidogrel led to enhanced inhibition of platelet aggregation and a reduction in adverse clinical outcomes in Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) patients undergoing coronary stenting when compared to 300 mg. Other studies have documented that when compared with both 300 and 600 mg loading doses of clopidogrel, a 60 mg loading dose of prasugrel has been documented to eventuate in faster onset, greater magnitude and more consistent levels of platelet inhibition as measured by light transmission aggregometry. Several studies have documented significantly greater platelet inhibition with prasugrel treatment when compared to high-dose clopidogrel therapy. The more potent P2Y12 ADP receptor antagonist prasugrel significantly reduced the composite endpoint of cardiovascular death, nonfatal MI, and nonfatal stroke in higher-risk ACS patients referred for PCI. The salutary effects referable to prasugrel treatment in this study were mostly due to a reduction in the incidence of myocardial infarction.

In the HORIZONS AMI trial patients with ST-segment elevation myocardial infarction who underwent primary PCI, anticoagulation with bivalirudin alone, as compared with heparin plus GP IIb/IIIa inhibitors, resulted in significantly reduced 30-day rates of major bleeding and net adverse clinical events. Despite these results and those from our laboratory documenting a profound bivalirudin-mediated effect on platelet aggregation, closer analysis of the HORIZONS AMI trial has documented a higher acute stent thrombosis rate in bivalirudin as opposed to GP IIb/IIIa inhibitor treated patients. The investigators have recently documented that the half life of bivalirudin, at the currently utilized dose during cardiac interventions is 29.3 minutes. The relatively short half life of this DTI in concert with the relatively long time period required to activate clopidogrel from a prodrug to its active metabolite, likely exposes patients to a vulnerable period when there is suboptimal platelet inhibition. It is plausible that this vulnerable period when platelet activity is not inhibited was the proximate cause of early stent thrombosis in the HORIZONS trial. Consequently, earlier acting, more potent thienopyridine therapy, i.e. prasugrel, when combined with bivalirudin treatment has the potential to reduce bleeding (compared with GP IIb/IIIa inhibitors) while preventing peri-procedural MI as well as providing protection from platelet-mediated stent thrombosis (compared with clopidogrel) during the vulnerable period following PCI.

The overwhelming majority of published data examining clinical outcomes or in-vivo pharmacodynamic and pharmacokinetic differences between clopidogrel and prasugrel have done so in PCI patients in whom bivalirudin was either not used or used very infrequently, i.e. in less than 10% of studied patients. However, at the present time in the United States, bivalirudin is the preeminent antithrombotic adjunctive therapy used during PCI. Consequently, comparative data regarding the effect of prasugrel and clopidogrel on platelet function in bivalirudin-treated patients is of significant clinical importance.

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02111
      • Tufts Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Signed informed consent before initiation of any study related procedures
2. Male or non-pregnant female aged 18 to ≤ 75 years
3. Referred for PCI or structural cardiac intervention and planned to receive bivalirudin treatment
4. Only subjects in whom the treating physician feels that clopidogrel and prasugrel are equivalent on the basis of available clinical literature will be included.

Exclusion Criteria:

1. Currently receiving glycoprotein IIb/IIIa inhibitors.
2. Have received prasugrel or clopidogrel within 2 weeks
3. Serum creatinine level >2.0
4. Hypersensitivity to bivalirudin, prasugrel, clopidogrel or aspirin
5. Currently on heparin administration or administered ≤ 4.5 h prior to intervention
6. Thrombocytopenia (<50,000/µL)
7. Severe systemic hypertension defined as systolic blood pressure >180 mm Hg and/or diastolic blood pressure >110 mm Hg
8. Body weight < 60 kg
9. Cardiogenic shock
10. Acute pericarditis
11. Active internal bleeding
12. History of bleeding diathesis within previous thirty days
13. Any history of intracranial hemorrhage, Transient ischemic attack (TIA ) or stroke
14. Arteriovenous malformations or aneurysms
15. Major surgical procedures or severe physical trauma within last thirty days.
16. Symptoms or findings suggestive of aortic dissection
17. Pregnancy
18. Participation in other clinical research studies involving the evaluation of investigational drugs or devices within 30 days of enrollment
19. Incompetent subjects or subjects otherwise unable to provide informed consent
20. Subjects in whom the treating physician believes that one agent (prasugrel or clopidogrel) is preferable over the other will be excluded from study participation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Prasugrel; Prasugrel oral loading dose of 60 mg administered preceding cardiac intervention	Drug: Prasugrel; Patients will be randomized to prasugrel or clopidogrel to assess the effect of these drugs on inhibition of platelet aggregation following the cessation of bivalirudin therapy.; Other Names: Effient
Active Comparator: Clopidogrel; Clopidogrel oral loading dose of 600 mg administered preceding cardiac intervention	Drug: Clopidogrel; Clopidogrel 600 mg as a loading dose immediately prior to the start of procedure and 75 mg daily thereafter; Other Names: Plavix

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in ADP-mediated Platelet Aggregation, APP, SFFLRN, AYPGKF.	To document the extent of inhibition of ADP mediated platelet aggregation following the discontinuation of bivalirudin therapy in patients treated with prasugrel as compared to patients treated with clopidogrel. The percent inhibition of platelet aggregation was measured by light transmission aggregometry of platelet-rich plasma in response to P2Y12 and PAR1 and PAR4 thrombin receptor agonists at baseline and at 1, 2, 4 and 16 h following the cessation of bivalirudin infusion. Platelet response to agonists: 20 mM ADP(P2Y12), 5 mM SFLLRN (PAR1), and 160 mM AYPGKF (PAR4) was performed. The magnitude of inhibition of platelet aggregation for each agonist was calculated as the mean final change from baseline in light transmission aggregometry at each time point.	Baseline, 60, 120, 240, 960 mins following termination of bivalirudin infusion

Collaborators and Investigators

• Sponsor: Tufts Medical Center
• Investigators: Principal Investigator: Carey Kimmelstiel, MD, Tufts Medical Center

Publications and helpful links

Helpful Links

• The CardioVascular Center at Tufts Medical Center
• Interventional Cardiology Center at Tufts Medical Center
• Carey Kimmelstiel, MD, Director, Adult Cardiac Catheterization Laboratory at Tufts Medical Center

Study record dates

Study Major Dates

• Study Start: July 1, 2013
• Primary Completion (Actual): July 1, 2014
• Study Completion (Actual): July 1, 2014

Study Registration Dates

• First Submitted: February 4, 2013
• First Submitted That Met QC Criteria: February 8, 2013
• First Posted (Estimate): February 12, 2013

Study Record Updates

• Last Update Posted (Actual): April 4, 2017
• Last Update Submitted That Met QC Criteria: March 31, 2017
• Last Verified: March 1, 2017

More Information

Terms related to this study

• Keywords: Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; bivalirudin
• Additional Relevant MeSH Terms: Myocardial Ischemia; Heart Diseases; Cardiovascular Diseases; Vascular Diseases; Arteriosclerosis; Arterial Occlusive Diseases; Coronary Disease; Coronary Artery Disease; Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Purinergic P2 Receptor Antagonists; Purinergic Antagonists; Purinergic Agents; Clopidogrel; Prasugrel Hydrochloride
• Other Study ID Numbers: PraCloBiv2013CK; TMCcardintervCK2013 (Other Identifier: Tufts Medical Center)