Switching patients from clopidogrel to prasugrel in acute coronary syndrome: effects of prasugrel loading dose on residual platelet reactivity

Switching from clopidogrel to prasugrel to protect early invasive treatment in acute coronary syndromes: Results of the switch over trial

BACKGROUND

Clopidogrel is used to pretreat patients with non-ST elevation acute coronary syndromes (NSTE-ACS), but prasugrel provides better platelet inhibition with improved outcome. However, switching from clopidogrel at the time of percutaneous coronary intervention (PCI) remains incompletely defined. Our aim was to compare the pharmacodynamic (PD) effects of 3 prasugrel loading doses (LDs; G1:10mg, G2: 30mg, and G3: 60mg) before PCI. A fourth group, continuing clopidogrel, served as control (G4).

METHODS

100 clopidogrel-pretreated patients were enrolled and blood collected before PCI, 30min, 1, 2, 4, 6, 24 and 48h thereafter. Platelet inhibition was measured by vasodilator-stimulated phosphoprotein phosphorylation (VASP) and Verify-Now assays. The end-points (EP) was the difference of PD effect at 4h between G3 and G4 (primary EP) with hierarchic evaluation between G2 and G1 versus G4 (secondary EP). A mixed-design ANOVA statistic was used to compare the four group scores over time.

RESULTS

Baseline characteristics were balanced across the groups. Only patients receiving 60 and 30mg prasugrel LDs showed a rapid (<1h) and significant (p<0.001) platelet inhibition up to 48h after PCI·The primary EP was met by G3 (p<0.0001), but also G2 scored different (p<0-001) from G4 at 4h after PCI. Similar findings were observed with Verify-Now. No differences in 30-day clinical outcomes were observed across groups.

CONCLUSIONS

Switching NSTE-ACS patients before PCI to prasugrel 60 or 30mg LDs determined a better and faster platelet inhibition than continuing clopidogrel, while PCI it is still underway.

Developments in Oral Antiplatelet Agents for the Treatment of Acute Coronary Syndromes

A review of the literature was conducted for clinical trials evaluating the antiplatelet P2Y12 receptor antagonists, clopidogrel, prasugrel, and ticagrelor, as well as the guidelines for the management of acute coronary syndrome (ACS) or myocardial infarction. Clinical guidelines recommend that patients with ACS be treated with dual oral antiplatelet therapy of aspirin plus clopidogrel, prasugrel, or ticagrelor. The selection of an appropriate antiplatelet agent depends on the treatment approach and a patient’s bleeding risk and clinical history. With respect to antiplatelet activity, prasugrel and ticagrelor demonstrate greater potency and less interpatient variability than clopidogrel. In phase III clinical trials, prasugrel and ticagrelor reduced the incidence of ischemic events in patients with ACS compared with clopidogrel. Ticagrelor and clopidogrel were associated with a similar risk of major bleeding, whereas patients receiving prasugrel had an increased risk of major bleeding versus those receiving clopidogrel. Pharmacists can provide guidance on the appropriate use of antiplatelet agents as well as the use of concomitant medications, while being vigilant for any potential drug interactions.

Administration of a loading dose has no additive effect on platelet aggregation during the switch from ongoing clopidogrel treatment to ticagrelor in patients with acute coronary syndrome

BACKGROUND

Ticagrelor outperforms clopidogrel in preventing cardiovascular events in acute coronary syndrome. Despite the inclusion of a loading dose in the Platelet Inhibition and Patient Outcomes (PLATO) trial for all patients randomized to ticagrelor, it may not be necessary in patients receiving ongoing clopidogrel therapy. The aim of the present study was to assess whether a ticagrelor loading dose is associated with a further platelet inhibition during the switch from clopidogrel to ticagrelor in patients with acute coronary syndrome receiving ongoing antiplatelet treatment.

METHODS AND RESULTS

Fifty patients with acute coronary syndrome receiving aspirin and clopidogrel treatment were randomly assigned to a starting dose of ticagrelor (group 1, 90 mg; group 2, 180 mg). Platelet aggregation was measured using multiple electrode aggregometry and standard light transmission aggregometry just before the switch and at 2, 6, 24, and 72 hours. No relevant difference in platelet aggregation was observed between the 2 study arms at baseline (P=0.256). Residual platelet aggregation was significantly reduced in both arms 2 hours after the first administration of ticagrelor (P<0.001 for both), with no difference in aggregation between groups (multiple electrode aggregometry, 17.6±7.2 versus 18.1±6 U; P=0.281). Similar results were observed with LTA.

CONCLUSIONS

Switching from clopidogrel to ticagrelor without a reloading dose is feasible, and it does not hinder platelet aggregation inhibition in patients with acute coronary syndrome. Further prospective studies are needed to assess the clinical relevance of our findings.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01795820.

In-hospital switching of oral P2Y12 inhibitor treatment in patients with acute coronary syndrome undergoing percutaneous coronary intervention: prevalence, predictors and short-term outcome

BACKGROUND

P2Y12 inhibitor switching has appeared in clinical practice as a consequence of prasugrel and ticagrelor availability, apart from clopidogrel, for use in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

METHODS

In the context of the GReek AntiPlatelet REgistry (GRAPE) we assessed the prevalence, predictive factors and short-term outcome of in-hospital P2Y12 inhibitor switching in 1794 ACS patients undergoing PCI.

RESULTS

Switching occurred in 636 (35.5%) patients of which in the form of clopidogrel to a novel agent, novel agent to clopidogrel and between prasugrel and ticagrelor in 574 (90.4%), 34 (5.3%) and 27 (4.3%) patients, respectively. Presentation to non PCI-capable hospital, bivalirudin use, age ≥75 years (inverse predictor), and regional trends emerged as predictive factors of switching to a novel agent. At combined in-hospital and one-month follow-up, propensity matched pairs analysis showed no differences in major adverse cardiovascular (MACE) or bleeding events between switching from clopidogrel to a novel agent vs novel agent constant administration. More Bleeding Academic Research Consortium type 1, type 2 and any type events and fewer MACE were seen when switching from clopidogrel to a novel agent vs only clopidogrel administration (23.7%, 3.8%, 30.6%, 1.2% vs 8.9%, 1.2%, 12.0%, 3.8% with P < .001, P = .03, P < .001 and P = .03 respectively).

CONCLUSIONS

In a real-life experience with contemporary antiplatelet treatment in ACS patients undergoing PCI, in-hospital switching represents common clinical practice. Clinical factors and regional practice differences seem to affect this strategy's choice, while switching to a novel agent may be associated with higher risk of bleeding.

High residual platelet reactivity on clopidogrel: its significance and therapeutic challenges overcoming clopidogrel resistance

Over the last decade, dual antiplatelet therapy has been the mainstay of the management of Acute Coronary Syndrome, with clopidogrel therapy providing clear benefits over aspirin monotherapy and becoming the agent of choice for the prevention of stent thrombosis. While newer antiplatelet agents have now become available, clopidogrel is still widely used due to its low cost and efficacy. However, many patients still experience recurrent ischemic events. A poor response of the platelets to clopidogrel, called High Residual Platelet Reactivity (HRPR), has been incriminated to account for this dilemma. Despite the absence of a universal definition of HRPR or the gold standard test to quantify it, persistent high platelet reactivity has consistently been associated with recurrence of ischemic events. Clopidogrel metabolism is highly variable, and genetics, comorbidities and drug interactions can affect it. In this article we review all definitions of HRPR, explore the available tests to quantify it, the clinical outcomes associated with it, as well as strategies that have shown success in overcoming it.