Platelet reactivity and clinical outcomes after coronary artery implantation of drug-eluting stents (ADAPT-DES): a prospective multicentre registry study

Optimizing P2Y12 receptor inhibition in patients with acute coronary syndrome on the basis of platelet function testing: impact of prasugrel and high-dose clopidogrel

OBJECTIVES

This study sought to evaluate the impact of treatment with prasugrel and high-dose clopidogrel on the basis of platelet function testing in patients with acute coronary syndrome (ACS) who are undergoing percutaneous coronary intervention (PCI).

BACKGROUND

The clinical impact of treatment with prasugrel in patients with ACS who have high platelet reactivity (HPR) is unknown.

METHODS

Patients with ACS who were pre-treated with clopidogrel and undergoing successful PCI were enrolled in a single-center, prospective registry. Platelet function was measured 12 to 36 h after PCI with the Multiplate device (Roche Diagnostics GmbH, Mannheim, Germany). Patients with HPR (>46 U) were switched to prasugrel or treated with high-dose clopidogrel, and those without HPR continued treatment with 75 mg of clopidogrel.

RESULTS

A total of 741 consecutive patients were enrolled in the study between September 2011 and August 2012, and 219 of these patients (29.5%) had HPR. Although platelet reactivity decreased after treatment adjustments in those with HPR, prasugrel provided significantly more potent platelet inhibition compared with high-dose clopidogrel (p < 0.0001). Compared with patients without HPR, the risk of all-cause death, myocardial infarction, stent thrombosis, or stroke at 1 year was significantly higher in the high-dose clopidogrel group (hazard ratio [HR]: 2.27; 95% confidence interval [CI]: 1.45 to 3.55; p < 0.0001), and patients who were switched to prasugrel had similar outcomes (HR: 0.90; 95% CI: 0.44 to 1.81; p = 0.76). Bleeding Academic Research Consortium (BARC) type 3/5 bleeding was also more frequent in patients treated with high-dose clopidogrel (HR: 2.09; 95% CI: 1.05 to 4.17; p = 0.04) than in patients switched to prasugrel (HR: 0.45; 95% CI: 0.11 to 1.91; p = 0.28). In a multivariate model, HPR with high-dose clopidogrel, but not with prasugrel, was an independent predictor of the composite ischemic endpoint (HR: 1.90; 95% CI: 1.17 to 3.08; p = 0.01).

CONCLUSIONS

Switching patients with ACS who have HPR to treatment with prasugrel reduces thrombotic and bleeding events to a level similar to that of those without HPR; however, there is a higher risk of both thrombotic and bleeding complications with high-dose clopidogrel.

Relationship Between Intravascular Ultrasound Guidance and Clinical Outcomes After Drug-Eluting Stents

Background—

Prior small to modest-sized studies suggest a benefit of intravascular ultrasound (IVUS) guidance in noncomplex lesions. Whether IVUS guidance is associated with improved clinical outcomes after drug-eluting stent (DES) implantation in an unrestricted patient population is unknown.

Methods and Results—

Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents (ADAPT-DES) was a prospective, multicenter, nonrandomized “all-comers” study of 8583 consecutive patients at 11 international centers designed to determine the frequency, timing, and correlates of stent thrombosis and adverse clinical events after DES. Propensity-adjusted multivariable analysis was performed to examine the relationship between IVUS guidance and 1-year outcomes. IVUS was utilized in 3349 patients (39%), and larger-diameter devices, longer stents, and/or higher inflation pressures were used in 74% of IVUS-guided cases. IVUS guidance compared with angiography guidance was associated with reduced 1-year rates of definite/probable stent thrombosis (0.6% [18 events] versus 1.0% [53 events]; adjusted hazard radio, 0.40; 95% confidence interval, 0.21–0.73; P =0.003), myocardial infarction (2.5% versus 3.7%; adjusted hazard radio, 0.66; 95% confidence interval, 0.49–0.88; P =0.004), and composite adjudicated major adverse cardiac events (ie, cardiac death, myocardial infarction, or stent thrombosis) (3.1% versus 4.7%; adjusted hazard radio, 0.70; 95% confidence interval, 0.55–0.88; P =0.002). The benefits of IVUS were especially evident in patients with acute coronary syndromes and complex lesions, although significant reductions in major adverse cardiac events were present in all patient subgroups those with including stable angina and single-vessel disease.

Conclusions—

In ADAPT-DES, the largest study of IVUS use to date, IVUS guidance was associated with a reduction in stent thrombosis, myocardial infarction, and major adverse cardiac events within 1 year after DES implantation.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00638794.

p2y12 receptor inhibitors in acute coronary syndromes: from the research laboratory to the clinic and vice versa

The P2Y12 receptor plays a pivotal role in platelet activation and aggregation through a complex cascade of actions. Laboratory and clinical data have convincingly shown the benefit of P2Y12 inhibition combined with aspirin in patients with acute coronary syndrome (ACS)/undergoing percutaneous coronary intervention (PCI). Newer agents - like prasugrel, ticagrelor, and cangrelor - provide more consistent, faster, and stronger platelet inhibition than clopidogrel. In large clinical trials newer agents have resulted in fewer ischemic complications (though with increased bleeding potential) than clopidogrel. High-risk subpopulations like ST-segment elevation myocardial infarction, diabetes, chronic kidney disease, elderly, and low body weight patients have been identified. A 'return to the laboratory' has been observed recently, with several pharmacodynamic studies being performed particularly in these cohorts. This interplay between research laboratory and clinical data may lead to a more efficient and safer use of P2Y12 inhibitors.

Impact of mild hypothermia on platelet responsiveness to aspirin and clopidogrel: an in vitro pharmacodynamic investigation

The combination of percutaneous coronary intervention (PCI) and therapeutic hypothermia in comatose patients after cardiac arrest due to an acute coronary syndrome has been reported to be safe and effective. However, recent investigations suggest that hypothermia may be associated with impaired response to clopidogrel and greater risk of thrombotic complications after PCI. This investigation aimed to evaluate the effect of hypothermia on the pharmacodynamic response of aspirin and clopidogrel in patients (n = 20) with ST elevation myocardial infarction undergoing primary PCI. Higher platelet reactivity (ADP stimulus) was observed in samples incubated at 33 °C compared with those at 37 °C (multiple electrode aggregometry, 235.2 ± 31.4 AU×min vs. 181.9 ± 30.2 AU×min, p < 0.001; VerifyNow P2Y12, 172.9 ± 20.3 PRU vs. 151.0 ± 19.3 PRU, p = 0.004). Numerically greater rates of clopidogrel poor responsiveness were also observed at 33 °C. No differences were seen in aspirin responsiveness. In conclusion, mild hypothermia was associated with reduced clopidogrel-mediated platelet inhibition with no impact on aspirin effects.

CLINICAL RELEVANCE

Mild therapeutic hypothermia is associated with impaired response to clopidogrel therapy, which might contribute to increase the risk of thrombotic events in ACS comatose patients undergoing PCI.

Pharmacodynamic evaluation of switching from ticagrelor to prasugrel in patients with stable coronary artery disease: Results of the SWAP-2 Study (Switching Anti Platelet-2)

OBJECTIVES

The goal of this study was to evaluate the pharmacodynamic effects of switching patients from ticagrelor to prasugrel.

BACKGROUND

Clinicians may need to switch between more potent P2Y12 inhibitors because of adverse effects or switch to the use of a once-daily dosing regimen due to compliance issues.

METHODS

After a 3- to 5-day run-in phase with a ticagrelor 180-mg loading dose (LD) followed by a ticagrelor 90-mg twice-daily maintenance dose (MD), aspirin-treated patients (N = 110) with stable coronary artery disease were randomized to continue ticagrelor or switch to prasugrel 10-mg once-daily MD, with or without a 60-mg LD. Pharmacodynamic assessments were defined according to P2Y12 reaction unit (PRU) (P2Y12 assay) and platelet reactivity index (vasodilator-stimulated phosphoprotein phosphorylation assay) at baseline (before and after the run-in phase) and 2, 4, 24, and 48 h and 7 days after randomization.

RESULTS

Platelet reactivity was significantly greater at 24 and 48 h after switching to prasugrel versus continued therapy with ticagrelor, although to a lesser extent in those receiving an LD. Mean PRU remained significantly higher in the combined prasugrel groups versus the ticagrelor group (least-squares mean difference: 46 [95% confidence interval 25 to 67]) and did not meet the primary noninferiority endpoint (upper limit of the confidence interval ≤45), although PRU in the prasugrel cohort was lower at 7 days than at 24 or 48 h. Accordingly, rates of high on-treatment platelet reactivity were higher at 24 and 48 h in both prasugrel groups. At 7 days, there was no difference in high on-treatment platelet reactivity rate between the combined prasugrel and ticagrelor groups.

CONCLUSIONS

Compared with continued ticagrelor therapy, switching from ticagrelor to prasugrel therapy was associated with an increase in platelet reactivity that was partially mitigated by the administration of an LD.

Direct oral anticoagulants and antiplatelet agents. Clinical relevance and options for laboratory testing

Oral anticoagulants and platelet receptor blockers are widely used in clinical practice with the aim of reducing the risk of thrombotic complications in patients with cardiovascular diseases. Their regular intake and adequate antithrombotic action is vital and this is way numerous assays have been developed for laboratory testing and monitoring of these agents. Available assays can be stratified into pharmacokinetic and pharmacodynamic assays. Such assays are increasingly used in clinical routine and their daily use is triggered by the advent of the novel direct oral anticoagulants (DOACs) as an alternative for vitamin K antagonist (VKA) treatment, which are dabigatran, rivaroxaban and apixaban, and by the advent of prasugrel or ticagrelor as an alternative for clopidogrel with regard to platelet P2Y12 receptor inhibition. In this review the most important and most commonly used laboratory assays are summarized as well as their clinical implications with the focus on DOACs as an alternative for VKAs and the different P2Y12 receptor blockers for antiplatelet treatment.

Impact of intraprocedural stent thrombosis during percutaneous coronary intervention: insights from the CHAMPION PHOENIX Trial (Clinical Trial Comparing Cangrelor to Clopidogrel Standard of Care Therapy in Subjects Who Require Percutaneous Coronary Intervention)

OBJECTIVES

This study sought to evaluate the clinical impact of intraprocedural stent thrombosis (IPST), a relatively new endpoint.

BACKGROUND

In the prospective, double-blind, active-controlled CHAMPION PHOENIX (Clinical Trial Comparing Cangrelor to Clopidogrel Standard of Care Therapy in Subjects Who Require Percutaneous Coronary Intervention) trial, cangrelor significantly reduced periprocedural and 30-day ischemic events in patients undergoing percutaneous coronary intervention (PCI), including IPST.

METHODS

An independent core laboratory blinded to treatment assignment performed a frame-by-frame angiographic analysis in 10,939 patients for the development of IPST, defined as new or worsening thrombus related to stent deployment at any time during the procedure. Adverse events were adjudicated by an independent, blinded clinical events committee.

RESULTS

IPST developed in 89 patients (0.8%), including 35 of 5,470 (0.6%) and 54 of 5,469 (1.0%) patients in the cangrelor and clopidogrel arms, respectively (odds ratio: 0.65; 95% confidence interval: 0.42 to 0.99; p = 0.04). Compared to patients without IPST, IPST was associated with a marked increase in composite ischemia (death, myocardial infarction [MI], ischemia-driven revascularization, or new-onset out-of-laboratory stent thrombosis [Academic Research Consortium]) at 48 h and at 30 days (29.2% vs. 4.5% and 31.5% vs. 5.7%, respectively; p < 0.0001 for both). After controlling for potential confounders, IPST remained a strong predictor of all adverse ischemic events at both time points.

CONCLUSIONS

In the large-scale CHAMPION PHOENIX trial, the occurrence of IPST was strongly predictive of subsequent adverse cardiovascular events. The potent intravenous adenosine diphosphate antagonist cangrelor substantially reduced IPST, contributing to its beneficial effects at 48 h and 30 days. (Clinical Trial Comparing Cangrelor to Clopidogrel Standard of Care Therapy in Subjects Who Require Percutaneous Coronary Intervention [PCI] [CHAMPION PHOENIX]; NCT01156571).

Consensus and update on the definition of on-treatment platelet reactivity to adenosine diphosphate associated with ischemia and bleeding

Dual antiplatelet therapy with aspirin and a P2Y12 receptor blocker is a key strategy to reduce platelet reactivity and to prevent thrombotic events in patients treated with percutaneous coronary intervention. In an earlier consensus document, we proposed cutoff values for high on-treatment platelet reactivity to adenosine diphosphate (ADP) associated with post-percutaneous coronary intervention ischemic events for various platelet function tests (PFTs). Updated American and European practice guidelines have issued a Class IIb recommendation for PFT to facilitate the choice of P2Y12 receptor inhibitor in selected high-risk patients treated with percutaneous coronary intervention, although routine testing is not recommended (Class III). Accumulated data from large studies underscore the importance of high on-treatment platelet reactivity to ADP as a prognostic risk factor. Recent prospective randomized trials of PFT did not demonstrate clinical benefit, thus questioning whether treatment modification based on the results of current PFT platforms can actually influence outcomes. However, there are major limitations associated with these randomized trials. In addition, recent data suggest that low on-treatment platelet reactivity to ADP is associated with a higher risk of bleeding. Therefore, a therapeutic window concept has been proposed for P2Y12 inhibitor therapy. In this updated consensus document, we review the available evidence addressing the relation of platelet reactivity to thrombotic and bleeding events. In addition, we propose cutoff values for high and low on-treatment platelet reactivity to ADP that might be used in future investigations of personalized antiplatelet therapy.

Current Concepts in the Clinical Utility of Platelet Reactivity Testing

The pharmacodynamic effect of clopidogrel varies among individuals; approximately a third will have high on-treatment platelet reactivity (HTPR) to adenosine diphosphate and may benefit from more intensive antiplatelet therapy. Platelet reactivity testing has an important role in monitoring the therapeutic efficiency of clopidogrel and the safety of more potent drugs that confer an increased bleeding risk, because it provides a direct measure of the biological effect of these drugs. Numerous studies have demonstrated an association between HTPR and the risk of cardiac events in acute coronary syndrome (ACS) or after percutaneous coronary intervention (PCI). While the prognostic value of platelet reactivity testing following PCI has been demonstrated repeatedly in cohort studies and meta-analyses, randomised controlled studies investigating the clinical utility of the technique to guide treatment decisions failed to improve clinical outcomes of clopidogrel-treated patients undergoing stent implantation. Available data suggest that platelet function monitoring may be carried out in clopidogrel-treated patients with a higher risk of thrombotic events. These include patient risk factors such as body mass index (BMI), type 2 diabetes, and those prior unexpected ischemic events such as stent thrombosis, as well as procedural risk factors. As we move towards conclusively defining a therapeutic window associated with both cardiovascular (upper threshold) and bleeding risk (lower threshold) for antiplatelet agents, platelet reactivity testing will become a central tool in the practice of personalised strategies.