Randomized Comparison of Intensified and Standard P2Y12-Receptor-Inhibition Before Elective Percutaneous Coronary Intervention: The SASSICAIA Trial.

BACKGROUND: Even among biomarker-negative patients undergoing elective percutaneous coronary intervention (PCI), periprocedural thrombotic and bleeding complications can lead to increased morbidity and mortality. Whether stronger platelet inhibition by an intensified oral loading strategy (ILS) before PCI impacts on outcomes among these patients in contemporary practice remains unclear. METHODS: This multicenter, randomized, assessor-blinded trial tested the hypothesis that in elective PCI prasugrel 60 mg (ILS) is superior to standard loading strategy with clopidogrel 600 mg regarding a composite primary end point of all-cause death, any myocardial infarction, definite/probable stent thrombosis, stroke, or urgent vessel revascularization. After PCI, all patients were on clopidogrel 75 mg/day and aspirin. The trial was terminated prematurely because of slower-than-expected recruitment and funding discontinuation. RESULTS: Of 781 patients included in the final analysis, 382 were assigned to ILS and 399 to standard loading strategy. At 30 days, the primary end point occurred in 66 patients (17.3%) assigned to ILS and 74 patients (18.6%) assigned to standard loading strategy (odds ratio, 0.92 [95% CI, 0.63-1.32]; P=0.64). Any myocardial infarction and Bleeding Academic Research Consortium ≥2 bleeding rates were similar among ILS and standard loading strategy groups 16.2% versus 17.5%, odds ratio, 0.91 (95% CI, 0.62-1.32), P=0.62 and 4.2% versus 4.8%, odds ratio 0.87 (95% CI, 0.44-1.73), P=0.70, respectively. CONCLUSIONS: In biomarker-negative stable and unstable angina patients undergoing elective PCI, the trial did not find a conclusive difference in efficacy or safety. This observation should be interpreted in the context of wide CIs and premature termination of the trial. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02548611.

Genomewide Association Study of Platelet Reactivity and Cardiovascular Response in Patients Treated With Clopidogrel: A Study by the International Clopidogrel Pharmacogenomics Consortium.

Antiplatelet response to clopidogrel shows wide variation, and poor response is correlated with adverse clinical outcomes. CYP2C19 loss-of-function alleles play an important role in this response, but account for only a small proportion of variability in response to clopidogrel. An aim of the International Clopidogrel Pharmacogenomics Consortium (ICPC) is to identify other genetic determinants of clopidogrel pharmacodynamics and clinical response. A genomewide association study (GWAS) was performed using DNA from 2,750 European ancestry individuals, using adenosine diphosphate-induced platelet reactivity and major cardiovascular and cerebrovascular events as outcome parameters. GWAS for platelet reactivity revealed a strong signal for CYP2C19*2 (P value = 1.67e-33). After correction for CYP2C19*2 no other single-nucleotide polymorphism reached genomewide significance. GWAS for a combined clinical end point of cardiovascular death, myocardial infarction, or stroke (5.0% event rate), or a combined end point of cardiovascular death or myocardial infarction (4.7% event rate) showed no significant results, although in coronary artery disease, percutaneous coronary intervention, and acute coronary syndrome subgroups, mutations in SCOS5P1, CDC42BPA, and CTRAC1 showed genomewide significance (lowest P values: 1.07e-09, 4.53e-08, and 2.60e-10, respectively). CYP2C19*2 is the strongest genetic determinant of on-clopidogrel platelet reactivity. We identified three novel associations in clinical outcome subgroups, suggestive for each of these outcomes.

Pharmacogenomic polygenic response score predicts ischaemic events and cardiovascular mortality in clopidogrel-treated patients.

AIMS: Clopidogrel is prescribed for the prevention of atherothrombotic events. While investigations have identified genetic determinants of inter-individual variability in on-treatment platelet inhibition (e.g. CYP2C19*2), evidence that these variants have clinical utility to predict major adverse cardiovascular events (CVEs) remains controversial. METHODS AND RESULTS: We assessed the impact of 31 candidate gene polymorphisms on adenosine diphosphate (ADP)-stimulated platelet reactivity in 3391 clopidogrel-treated coronary artery disease patients of the International Clopidogrel Pharmacogenomics Consortium (ICPC). The influence of these polymorphisms on CVEs was tested in 2134 ICPC patients (N = 129 events) in whom clinical event data were available. Several variants were associated with on-treatment ADP-stimulated platelet reactivity (CYP2C19*2, P = 8.8 × 10-54; CES1 G143E, P = 1.3 × 10-16; CYP2C19*17, P = 9.5 × 10-10; CYP2B6 1294 + 53 C > T, P = 3.0 × 10-4; CYP2B6 516 G > T, P = 1.0 × 10-3; CYP2C9*2, P = 1.2 × 10-3; and CYP2C9*3, P = 1.5 × 10-3). While no individual variant was associated with CVEs, generation of a pharmacogenomic polygenic response score (PgxRS) revealed that patients who carried a greater number of alleles that associated with increased on-treatment platelet reactivity were more likely to experience CVEs (ß = 0.17, SE 0.06, P = 0.01) and cardiovascular-related death (ß = 0.43, SE 0.16, P = 0.007). Patients who carried eight or more risk alleles were significantly more likely to experience CVEs [odds ratio (OR) = 1.78, 95% confidence interval (CI) 1.14-2.76, P = 0.01] and cardiovascular death (OR = 4.39, 95% CI 1.35-14.27, P = 0.01) compared to patients who carried six or fewer of these alleles. CONCLUSION: Several polymorphisms impact clopidogrel response and PgxRS is a predictor of cardiovascular outcomes. Additional investigations that identify novel determinants of clopidogrel response and validating polygenic models may facilitate future precision medicine strategies.

Smoking and outcomes following guided de-escalation of antiplatelet treatment in acute coronary syndrome patients: a substudy from the randomized TROPICAL-ACS trial.

AIMS: Prior analyses disclosed variations in antiplatelet drug response and clinical outcomes between smokers and non-smokers, thus the safety and efficacy of any dual antiplatelet therapy (DAPT) de-escalation strategy may differ in relation to smoking status. Hence, we assessed the impact of smoking on clinical outcomes and adenosine diphosphate-induced platelet aggregation following guided de-escalation of DAPT in invasively managed acute coronary syndrome (ACS) patients. METHODS AND RESULTS: The multicentre TROPICAL-ACS trial randomized 2610 biomarker-positive ACS patients 1:1 to standard treatment with prasugrel for 12 months (control group) or a platelet function testing guided de-escalation of DAPT. Current smokers (n = 1182) showed comparable event rates between study groups [6.6% vs. 6.6%; hazard ratio (HR) 1.0, 95% confidence interval (CI) 0.64-1.56, P > 0.99]. In non-smokers (n = 1428), a guided DAPT de-escalation was associated with a lower 1-year incidence of the primary endpoint [cardiovascular death, myocardial infarction, stroke, or bleeding ≥ Grade 2 according to Bleeding Academic Research Consortium (BARC) criteria] compared with control group patients (7.9% vs. 11.0%; HR 0.71, 95% CI 0.50-0.99, P = 0.048). This reduction was mainly driven by a lower rate of BARC ≥ Grade 2 bleedings (5.2% vs. 7.7%; HR 0.68, 95% CI 0.45-1.03, P = 0.066). There was no significant interaction of smoking status with treatment effects of guided DAPT de-escalation (Pint = 0.23). Adenosine diphosphate-induced platelet aggregation values were higher in current smokers [median 28 U, interquartile range (IQR: 20-40)] vs. non-smoker [median 24 U (16-25), P < 0.0001] in the control group and in current smokers [median 42 U, IQR (27-68)] vs. non-smoker [median 37 U, IQR (25-55), P < 0.001] in the monitoring group. CONCLUSION: Guided DAPT de-escalation appears to be equally safe and effective in smokers and non-smokers. Regardless of smoking status and especially for those patients deemed unsuitable for 1 year of potent platelet inhibition this DAPT strategy might be used as an alternative antiplatelet treatment regimen.

Antagonizing P2Y12 Receptor Inhibitors: Current and Future Options.

There are clinical scenarios where the balance between the risk of ischemic and bleeding events leads to the clinical decision to reverse the antiplatelet effect of P2Y12 receptor inhibitors. These scenarios comprise emergency situations such as active severe bleeding, urgent procedures with presumed high bleeding risk, or major trauma with (anticipated) bleeding. Supplementation of platelets has been investigated in ex vivo as well as in in vivo studies. These studies indicate that the inhibition of adenosine diphosphate-induced aggregation by the irreversibly binding thienopyridine derivatives clopidogrel and prasugrel can be reversed by administration of platelet concentrates. Supplementation of platelets in patients on prasugrel is more effective if this can be transfused > 6 hours after last dosing. Studies on the reversal effect obtained by administration of platelet concentrates in patients on ticagrelor show conflicting results. Experimental data suggest that administration of serum albumin might increase the reversal effect. A monoclonal antibody fragment (PB2452) for neutralizing ticagrelor is currently in clinical development. A recently published first in man study shows that reversal of platelet inhibition occurs within 5 minutes after start of administration and the effect is maintained for 20 to 24 hours after a 16-hour infusion which is by far the most effective approach for reversal of ticagrelor.

Updated Expert Consensus Statement on Platelet Function and Genetic Testing for Guiding P2Y12 Receptor Inhibitor Treatment in Percutaneous Coronary Intervention.

Dual-antiplatelet therapy (DAPT) with aspirin and a P2Y12 receptor inhibitor is the standard treatment for patients undergoing percutaneous coronary intervention. The availability of different P2Y12 receptor inhibitors (clopidogrel, prasugrel, ticagrelor) with varying levels of potency has enabled physicians to contemplate individualized treatment regimens, which may include escalation or de-escalation of P2Y12-inhibiting therapy. Indeed, individualized and alternative DAPT strategies may be chosen according to the clinical setting (stable coronary artery disease vs. acute coronary syndrome), the stage of the disease (early- vs. long-term treatment), and patient risk for ischemic and bleeding complications. A tailored DAPT approach may be potentially guided by platelet function testing (PFT) or genetic testing. Although the routine use of PFT or genetic testing in percutaneous coronary intervention-treated patients is not recommended, recent data have led to an update in guideline recommendations that allow considering selective use of PFT for DAPT de-escalation. However, guidelines do not expand on when to implement the selective use of such assays into decision making for personalized treatment approaches. Therefore, an international expert consensus group of key leaders from North America, Asia, and Europe with expertise in the field of antiplatelet treatment was convened. This document updates 2 prior consensus papers on this topic and summarizes the contemporary updated expert consensus recommendations for the selective use of PFT or genotyping in patients undergoing percutaneous coronary intervention.

Diurnal Variability of On-Treatment Platelet Reactivity in Clopidogrel versus Prasugrel Treated Acute Coronary Syndrome Patients: A Pre-Specified TROPICAL-ACS Sub-Study.

Long-term evidence supports a clustering of cardiovascular events in the early morning and smaller mechanistic studies in aspirin-treated patients have shown increased platelet reactivity at the end of the dosing interval. Comparative pharmacodynamic analyses for different adenosine diphosphate (ADP) receptor inhibitors in percutaneous coronary intervention-treated acute coronary syndrome (ACS) patients are lacking and this pre-specified analysis from the randomized Testing Responsiveness To Platelet Inhibition On Chronic Antiplatelet Treatment For Acute Coronary Syndromes (TROPICAL-ACS) trial aimed for the first time at investigating diurnal variability of on-treatment platelet reactivity in clopidogrel versus prasugrel treated patients. TROPICAL-ACS randomized 2,610 ACS patients to either treatment with prasugrel (control group) or to a platelet function testing-guided de-escalation of anti-platelet treatment with a switch to clopidogrel (guided de-escalation group). This study design enabled a diurnal comparison of on-prasugrel versus on-clopidogrel treatment platelet reactivity under steady-state conditions. For 2,526 patients (97%), both the exact time of blood sampling and the ADP-induced platelet aggregation value (in units, Multiplate analyser) were available. Platelet reactivity in patients on clopidogrel (n = 1,265) was higher and subject to significant diurnal variability (p = 0.019) with a peaking of platelet reactivity in the early morning (5-10 a.m.). In prasugrel-treated patients (n = 1,261), there was no sign for diurnal variability (p = 0.174) or a peaking of platelet reactivity in the morning. The potent ADP receptor inhibitor prasugrel is not subject to diurnal variability while we observed a significant diurnal variability of on-clopidogrel platelet reactivity. The clinical impact of this observation may differ for patients with and without an adequate response to clopidogrel treatment and the issue of diurnal variability of platelet reactivity in ACS patients warrants further investigation.

P2Y12-ADP Receptor Blockade in Chronic Kidney Disease Patients With Acute Coronary Syndromes.

Because of its high prevalence, chronic kidney disease (CKD) remains a major health hazard throughout the world. Patients with CKD have a high prevalence and incidence of acute coronary syndromes (ACS). Despite decades of improved care, their higher risk profile persists and cardiovascular diseases remain their leading cause of death. Along with the reduction of glomerular filtration rate, several physiological processes are impacted and participate in the pathophysiology of ischemic and bleeding events. CKD is associated with an accelerated and severe course of atherothrombotic disease, and this relates to a modified vascular milieu with alterations on the level of the coagulation cascade and platelet aggregation. In addition, pharmacokinetics of several drugs, in particular antithrombotics, are altered and differ from that of non-CKD patients. Patients with CKD therefore represent a challenging population for both physicians and researchers. In addition to these perturbations of physiological processes, CKD patients face 2 major issues. First, there is a clear gap in scientific research as they are commonly underrepresented or excluded from major clinical trials. This is particularly true regarding antithrombotic treatment during ACS. Second, there is a gap in offering evidence-based treatment for these patients including state-of-the art options for revascularization and modern antiplatelet treatment, both of which are commonly underused. During the last decade, new potent oral P2Y12-ADP receptor antagonists, prasugrel and ticagrelor, which are more potent antiplatelet agents compared with clopidogrel, were introduced for ACS treatment. However, despite the fact that CKD patients represent a large proportion of those experiencing an ACS and are considered at high risk, there is a lack of dedicated trials and we are left with subgroup analysis of large randomized clinical trials were stage 4 and dialysis patients were rare. In the present review we summarize the mechanisms involved in the high ischemic and bleeding risk of CKD patients and the risk-benefit ratio of potent antiplatelet drugs during ACS.

Meta-Analysis of Potent P2Y12-ADP Receptor Antagonist Therapy Compared to Clopidogrel Therapy in Acute Coronary Syndrome Patients with Chronic Kidney Disease.

BACKGROUND: The clinical benefit of anti-platelet agents in patients with chronic kidney disease (CKD) is uncertain. In addition, the risk-benefit ratio of potent oral P2Y12-adenosine diphosphate (ADP) receptor antagonists (PPAs), namely, prasugrel and ticagrelor, compared with clopidogrel in CKD patients suffering from acute coronary syndrome (ACS) remains unknown. OBJECTIVE: We performed a meta-analysis of all studies comparing the clinical outcomes of PPA and clopidogrel therapy in CKD patients suffering from ACS. METHODS: We searched PubMed, the Cochrane library, Google Scholar, Clinical trial.org and the abstracts of international cardiology congresses from April 2000 to October 2017. Clinical studies comparing PPA with clopidogrel in ACS patients with CKD were selected. Our literature research identified five studies which were included in the meta-analysis. The primary endpoint was a composite of major adverse cardiovascular events (MACEs) at the latest follow-up available. Secondary endpoint included bleedings. RESULTS: We included data from three sub-group analysis of randomized clinical trials and two prospective observational studies (n = 31,234). Overall, PPAs were associated with lower rates of major cardiovascular events, with a pooled hazard ratio (pHR) of 0.88 (95% confidence interval [CI]: 0.79-0.99; p = 0.03), without increased bleedings (pHR = 1.10) (95% CI: 0.95-1.27; p = 0.18). In a sensitivity analysis restricted to studies enrolling invasively managed patients, the benefit of PPA on MACE was maintained (pHR = 0.85) (95% CI: 0.77-0.93; p < 0.001), including a reduction in mortality (pHR = 0.82) (95% CI: 0.7-0.96; p = 0.016). CONCLUSION: Compared with clopidogrel, PPAs were associated with a reduced rate of MACE without increased bleedings in CKD patients with ACS. Among invasively managed patients, this benefit from PPA included a reduction in mortality.

Genotype-Phenotype Association and Impact on Outcomes following Guided De-Escalation of Anti-Platelet Treatment in Acute Coronary Syndrome Patients: The TROPICAL-ACS Genotyping Substudy.

BACKGROUND: Phenotype-guided de-escalation (PGDE) of P2Y12-inhibitor treatment with an early switch from prasugrel to clopidogrel was identified as an effective alternative treatment strategy in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI). The Testing Responsiveness to Platelet Inhibition on Chronic Antiplatelet Treatment for Acute Coronary Syndromes (TROPICAL-ACS) Genotyping Substudy aimed to investigate whether CYP2C19 genotypes correlate with on-treatment platelet reactivity (PR) in ACS patients treated with clopidogrel or prasugrel and thus might be useful for guidance of early de-escalation of anti-platelet treatment. METHODS AND RESULTS: A total of 603 ACS consecutive patients were enrolled in four centres (23.1% of the overall TROPICAL-ACS population). Rapid genotyping (Spartan RX) for CYP2C19*2, *3 and *17 alleles was performed. Associations between PR and the primary and secondary endpoints of the TROPICAL-ACS trial and CYP2C19*2 and CYP2C19*17 carrier status were evaluated.For the PGDE group, the on-clopidogrel PR significantly differed across CYP2C19*2 (p < 0.001) and CYP2C19*17 genotypes (p = 0.05). Control group patients were not related (p = 0.90, p = 0.74) to on-prasugrel PR. For high PR versus non-high PR patients within the PGDE group, significant differences were observed for the rate of CYP2C19*2 allele carriers (43% vs. 28%, p = 0.007). CONCLUSION: CYP2C19*2 and CYP2C19*17 carrier status correlates with PR in ACS patients treated with clopidogrel and thus might be useful for pre-selecting patients who will and who may not be suitable for PGDE of anti-platelet treatment. Regarding phenotype-guided treatment, we did not observe added benefit of genotyping to predict ischaemic and bleeding risk in patients who underwent a PGDE approach. CLINICAL TRIAL REGISTRATION: URL: https//www.clinicaltrials.gov. Unique Identifier: NCT: 01959451.

Comparison of Platelet Function Guided Versus Unguided Treatment With P2Y12 Inhibitors in Patients With Acute Myocardial Infarction (from the Hungarian Myocardial Infarction Registry).

Evidence is conflicting regarding the clinical benefits of selecting P2Y12 inhibitors based on platelet function testing (PFT). Between March 1, 2013 and March 1, 2014, we collected clinical characteristics and platelet function data in a nationwide acute myocardial infarction (AMI) registry from 15 interventional cardiology centers in Hungary. The risk of all-cause mortality at 1 year were compared after propensity score (PS) matching between patients receiving PFT-guided and unguided P2Y12-inhibitor therapies. High platelet reactivity on clopidogrel (HPRoC) was uniformly defined with the Multiplate assay. A total of 5,583 patients with AMI and coronary intervention were registered. After exclusion of cases with contraindication to prasugrel, propensity matching resulted in a sample of 2,104 patients with well-adjusted characteristics. Clopidogrel was the dominant P2Y12 inhibitor in both groups (unguided: 96% vs PFT guided: 85%, p <0.001). In the PFT-guided group, 19% of patients had HPRoC and 77% of them were switched to prasugrel. According to the adjusted analysis, all-cause mortality at 1 year was significantly lower in the PFT-guided compared with the unguided group (hazard ratio 0.57 [95% confidence interval 0.43 to 0.77], p <0.001). Although prasugrel treatment was not associated with lower all-cause mortality in the overall cohort, patients with HPRoC who switched to prasugrel had significantly lower mortality when compared with those continuing clopidogrel (hazard ratio 0.33 [95% confidence interval 0.12 to 0.92], p <0.05). In conclusion, in patients with AMI, PFT-guided treatment with a high rate of switchover to prasugrel was associated with a lower risk of mortality. Prasugrel was a predictor of lower mortality in patients with HPRoC but not in the overall cohort of AMI.

Genome-wide and candidate gene approaches of clopidogrel efficacy using pharmacodynamic and clinical end points-Rationale and design of the International Clopidogrel Pharmacogenomics Consortium (ICPC).

RATIONALE: The P2Y12 receptor inhibitor clopidogrel is widely used in patients with acute coronary syndrome, percutaneous coronary intervention, or ischemic stroke. Platelet inhibition by clopidogrel shows wide interpatient variability, and high on-treatment platelet reactivity is a risk factor for atherothrombotic events, particularly in high-risk populations. CYP2C19 polymorphism plays an important role in this variability, but heritability estimates suggest that additional genetic variants remain unidentified. The aim of the International Clopidogrel Pharmacogenomics Consortium (ICPC) is to identify genetic determinants of clopidogrel pharmacodynamics and clinical response. STUDY DESIGN: Based on the data published on www.clinicaltrials.gov, clopidogrel intervention studies containing genetic and platelet function data were identified for participation. Lead investigators were invited to share DNA samples, platelet function test results, patient characteristics, and cardiovascular outcomes to perform candidate gene and genome-wide studies. RESULTS: In total, 17 study sites from 13 countries participate in the ICPC, contributing individual patient data from 8,829 patients. Available adenosine diphosphate-stimulated platelet function tests included vasodilator-stimulated phosphoprotein assay, light transmittance aggregometry, and the VerifyNow P2Y12 assay. A proof-of-principle analysis based on genotype data provided by each group showed a strong and consistent association between CYP2C19*2 and platelet reactivity (P value=5.1 × 10-40). CONCLUSION: The ICPC aims to identify new loci influencing clopidogrel efficacy by using state-of-the-art genetic approaches in a large cohort of clopidogrel-treated patients to better understand the genetic basis of on-treatment response variability.

Prolonging Ticagrelor Beyond a Year of Acute Coronary Syndrome: Worth or Harmful?

Platelet activation plays a central role in triggering and complicating acute coronary syndromes, especially in case of stent thrombosis and myocardial infarction. On top of aspirin, P2Y12- inhibitors are successfully used to treat and prevent these events for a duration of one year after an acute coronary episode or 6 months after drug-eluting stent implantation. However, patients with acute coronary syndromes remain at heightened risk for recurrent ischemic events after the recommended durations of P2Y12-inhibitors and therefore, prolonging treatment is often considered in clinical practice. However, the higher risk for bleeding limits the utility of such approach to a restricted group who is still poorly defined by available measures. This review aims to discuss potential benefits and highlight important pitfalls of prolonged treatment with P2Y12-inhibitors, with a focus on ticagrelor, an attractive reversible P2Y12-inhibitor in patients after myocardial infarction.

Impact of Test Conditions on ADP-Induced Platelet Function Results With the Multiplate Assay: Is Further Standardization Required?

BACKGROUND: Platelet function testing was suggested to help tailor P2Y12-inhibitor therapy; however, the lack of proper standardization is still a limitation. METHODS: In a prospective study, we enrolled clopidogrel-treated and P2Y12-inhibitor naive patients to investigate the influence of (1) time from blood collection, (2) stability of the stored Adenosine diphosphate (ADP) reagent, and (3) the use of enoxaparin on results of the Multiplate assay. Measurements were performed from samples kept for 0, 30, 60, 120, and 240 minutes at room temperature before processing. To determine the impact of the reagent stability, freshly thawed ADP was compared with ADP kept for 3 to 5 or 8 to 13 days at 2°C to 8°C. Finally, samples containing enoxaparin at therapeutic or prophylactic doses were compared with enoxaparin-free blood. RESULTS: A total of 180 measurements were performed. ADP-stimulated platelet reactivity values decreased significantly over time (67 ± 40 U to 68 ± 37 U to 58 ± 37 U to 45 ± 33 U to 35 ± 33 U; P < .0001). Consequently, a dramatic reduction was observed in the proportion of patients with high platelet reactivity ( P < .0001). A significant drop in platelet reactivity was observed with ADP stored for 8 to 13 days as compared to freshly thawed ADP ( P = .011). Enoxaparin triggered a slight, concentration-dependent increase in platelet reactivity ( P < .05). CONCLUSION: Test conditions may have profound impacts on the obtained results with the Multiplate assay. Our findings highlight the large influence of the time from sample collection until testing, suggesting that measurements should be performed within an hour of blood collection.

International Expert Consensus on Switching Platelet P2Y12 Receptor-Inhibiting Therapies.

Dual antiplatelet therapy with aspirin and a P2Y12 inhibitor is the treatment of choice for the prevention of atherothrombotic events in patients with acute coronary syndromes and for those undergoing percutaneous coronary interventions. The availability of different oral P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) has enabled physicians to contemplate switching among therapies because of specific clinical scenarios. The recent introduction of an intravenous P2Y12 inhibitor (cangrelor) further adds to the multitude of modalities and settings in which switching therapies may occur. In clinical practice, it is not uncommon to switch P2Y12 inhibitor, and switching may be attributed to a variety of factors. However, concerns about the safety of switching between these agents have emerged. Practice guidelines have not fully elaborated on how to switch therapies, leaving clinicians with limited guidance on when and how to switch therapies when needed. This prompted the development of this expert consensus document by key leaders from North America and Europe with expertise in basic, translational, and clinical sciences in the field of antiplatelet therapy. This expert consensus provides an overview of the pharmacology of P2Y12 inhibitors, different modalities and definitions of switching, and available literature and recommendations for switching between P2Y12 inhibitors.

A randomised trial on platelet function-guided de-escalation of antiplatelet treatment in ACS patients undergoing PCI. Rationale and design of the Testing Responsiveness to Platelet Inhibition on Chronic Antiplatelet Treatment for Acute Coronary Syndromes (TROPICAL-ACS) Trial.

Outcomes of acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) have been significantly improved with the use of potent P2Y12 receptor inhibitors like prasugrel. While most of the ischaemic risk reduction for prasugrel versus clopidogrel was demonstrated in the early treatment period, the risk of bleeding became particularly prominent during the chronic course of therapy. It may therefore be a valid approach to substitute prasugrel for clopidogrel in the early phase of chronic antiplatelet treatment after PCI. In the Testing Responsiveness To Platelet Inhibition On Chronic Antiplatelet Treatment For Acute Coronary Syndromes (TROPICAL-ACS) trial, we aim to compare standard prasugrel therapy with a de-escalating antiplatelet treatment approach guided by platelet function testing (PFT). The study is an investigator-initiated European multicentre, randomised clinical trial in biomarker-positive ACS patients after successful PCI. Two thousand six hundred patients will be randomised prior to hospital discharge in a 1:1 fashion to either receive standard prasugrel therapy (control group) or de-escalating therapy (one-week prasugrel followed by one-week clopidogrel and PFT-guided maintenance therapy from day 14 after hospital discharge, monitoring group). Patients of the monitoring group with high on-clopidogrel platelet reactivity (HPR) based on Multiplate analyzer testing (HPR: ≥ 46U per consensus definition) will be switched back to prasugrel, whereas those without HPR (<46 U) will continue clopidogrel treatment. The overall study treatment duration will be one year in both groups. The primary endpoint of the study is net clinical benefit (combined incidence of cardiovascular death, myocardial infarction, stroke and bleeding ≥ grade 2 according to BARC criteria) one-year after randomisation. TROPICAL-ACS is the first large-scale, randomised controlled trial assessing the clinical value of a PFT-guided de-escalation of antiplatelet treatment in biomarker positive ACS patients undergoing PCI.

Platelet Function Testing in Patients on Antiplatelet Medications.

Guidelines provide a Class IA recommendation for the use of dual antiplatelet therapy in patients undergoing percutaneous coronary intervention (PCI). However, there is interindividual variability in the pharmacodynamic response to antiplatelet medications. Some patients present with a status of high on-treatment platelet reactivity (HPR) during platelet function testing after standard doses of antiplatelet drugs, reflecting a failure to achieve adequate platelet inhibition. As an example, patients with HPR on clopidogrel are at increased risk for thrombotic events, particularly for stent thrombosis and myocardial infarction, but cardiovascular mortality is also elevated. On the contrary, low on-treatment platelet reactivity or an enhanced response to antiplatelet medications has been linked to a higher risk for bleeding. Although both thrombotic and bleeding events are multifactorial in origin, there is supportive evidence for the prognostic value of platelet function testing for risk prediction of both sides of the coin. However, although small studies have provided evidence that treatment adjustments based on platelet function testing results may improve clinical outcomes, the available randomized controlled trials showed no benefit of modifying antiplatelet treatment based on platelet function testing. This review presents the current evidence regarding platelet function testing in patients undergoing PCI. The prognostic value of platelet function testing regarding ischemic and bleeding events is highlighted. Furthermore, the value of platelet function testing for guiding treatment and possible explanations for the so-far negative trial results are presented. The possible future role of platelet function testing for individualized antiplatelet treatment regimens in high-risk patients will be also discussed.

Assessment of platelet function in patients receiving tirofiban early after primary coronary intervention.

BACKGROUND: Following percutaneous coronary intervention, combined antiplatelet therapy is necessary. Platelet function testing (PFT) has prognostic value and may be applied in the risk assessment of acute coronary syndrome. In case of combined antiplatelet therapy, PFT may require special laboratory methods, as different antiplatelet agents may influence test results. MATERIALS AND METHODS: Platelet functions were measured in stent thrombosis-segment elevation myocardial infarction patients receiving aspirin, clopidogrel, and tirofiban. The first sampling was obtained immediately after the termination of administration of tirofiban. The second sample was drawn at a randomly assigned time between 1 and 6 h. The third sampling was done after a minimum of 24 h of tirofiban cessation. Adenosine diphosphate (ADP)- and thrombin receptor-activating peptide (TRAP)-induced aggregations were measured. RESULTS: Thirty-seven patients were included. Both TRAP- and ADP-induced aggregation values were significantly lower immediately after tirofiban termination, than after 24 h [TRAP: 26.41 ± 25.00 units (U) vs. 109.86 ± 23.69 U, p < 0.0001; ADP: 17.43 ± 10.10 U vs. 43.92 ± 23.35 U, p ≤ 0.0001]. Elimination half-life of tirofiban and clopidogrel were 1.34 ± 0.49 and 1.269 ± 0.78, respectively. CONCLUSION: ADP-induced residual platelet reactivity is significantly influenced by the presence of concurrent glycoprotein IIb/IIIa inhibitor. In patients receiving combined antiplatelet treatment, ADP-receptor-specific efficiency measurements are valid only after total elimination of GPIIb/IIIa inhibitors.

Prevention of cardiovascular events with antiplatelet treatment: does time of intake matter for aspirin and ADP receptor blockers?

Long-term evidence supports a clustering of cardiovascular events in the early morning. Several studies have shown that platelet hyper-reactivity to various stimuli is also present at this period of the day. However, the idea of treatment strategies reflecting the circadian variation in platelet reactivity has been largely neglected so far, and this is true despite the huge number of patients being treated with these drugs. Some pharmacodynamic data suggest that early-morning platelet hyper-reactivity may be overcome by shifting aspirin intake to the bedtime. However, there is lack of evidence whether shifting the time of intake or splitting the daily dose of P2Y12-inhibitors with a regular QD dosing (clopidogrel or prasugrel) to the evening would be effective to overcome platelet hyper-reactivity or to suppress the excess of cardiovascular events observed during morning hours. Further research is warranted to clarify whether such a simple and costless effort like dose shifting or splitting may be beneficial to prevent cardiovascular events.