Population Pharmacokinetic/Pharmacodynamic Models for P2Y12 Inhibitors: A Systematic Review and Clinical Appraisal Using Exposure Simulation

BACKGROUND AND OBJECTIVE

Recent research indicates a correlation between plasma concentration of P2Y12 inhibitors and clinical events, particularly bleeding, which significantly impeded their clinical therapeutic performance. It is therefore vital to delve into the factors that might affect the plasma concentration. The study aims to summarize population pharmacokinetics/pharmacodynamics (PopPKPD) models for commonly prescribed P2Y12 inhibitors (clopidogrel, prasugrel, and ticagrelor) and assess bleeding risk in specific individual groups.

METHODS

The PopPKPD models of P2Y12 inhibitors were collected and summarized based on predetermined inclusion and exclusion criteria. The collected models were replicated in simulations, which were used to assess factors affecting plasma concentrations of P2Y12 inhibitors. Simulation results for special populations were compared to therapeutic window based on reported exposure-effect relationships (PK/PD-related bleeding and thrombotic clinical outcomes) to predict bleeding risk in special populations with different dosing regimens and cumulative covariates.

RESULT

Finally, 12 studies were included for PK simulation, 7 of which that also included PD data were subjected to further analysis, with the majority being based on Phase I or II trials. Simulations showed that several covariates such as female gender, weight, elderly can significantly impact on exposure, with special populations reaching up to 179% of the general population. However, after dose adjustment, blood concentrations for special populations can reach approximately ±20% of general population exposure. Therefore, lowering the maintenance dose of ticagrelor from 90 to 60 mg bid was first recommended to reduce bleeding risk without significantly increasing ischemic risk, particularly in elderly, small-weight Asian females.

CONCLUSION

Lowering the maintenance dose of ticagrelor from 90 to 60 mg bid effectively reduces bleeding risk without increasing thrombotic infarction risk in elderly, small-weight Asian females.

Switching from Dual Antiplatelet Therapy with Aspirin Plus a P2Y12 Inhibitor to Dual Pathway Inhibition with Aspirin Plus Vascular-Dose Rivaroxaban: The Switching Anti-Platelet and Anti-Coagulant Therapy (SWAP-AC) Study

BACKGROUND

 To date, there are no data on switching to dual pathway inhibition (DPI) patients who have completed a guideline-recommended dual antiplatelet therapy (DAPT) regimen.

OBJECTIVES

 To assess the feasibility of switching from DAPT to DPI and to compare the pharmacodynamic (PD) profiles of these treatments.

METHODS

 This was a prospective, randomized, PD study conducted in 90 patients with chronic coronary syndrome (CCS) on DAPT with aspirin (81 mg/qd) plus a P2Y12 inhibitor (clopidogrel [75 mg/qd; n = 30], ticagrelor [90 mg/bid; n = 30], or prasugrel [10 mg/qd; n = 30]). Patients in each cohort were randomized to maintain DAPT or switch to DPI (aspirin 81 mg/qd plus rivaroxaban 2.5 mg/bid). PD assessments included: VerifyNow P2Y12 reaction units; light transmittance aggregometry following stimuli with adenosine diphosphate (ADP), tissue factor (TF), and a combination of collagen, ADP, and TF (maximum platelet aggregation %); thrombin generation (TG). Assays were performed at baseline and 30 days postrandomization.

RESULTS

 Switching from DAPT to DPI occurred without major side effects. DAPT was associated with enhanced P2Y12 inhibition, while DPI with reduced TG. Platelet-mediated global thrombogenicity (primary endpoint) showed no differences between DAPT and DPI in the ticagrelor (14.5% [0.0-63.0] vs. 20.0% [0.0-70.0]; p = 0.477) and prasugrel (20.0% [0.0-66.0] vs. 4.0% [0.0-70.0]; p = 0.482), but not clopidogrel (27.0% [0.0-68.0] vs. 53.0% [0.0-81.0]; p = 0.011), cohorts.

CONCLUSION

 In patients with CCS, switching from different DAPT regimens to DPI was feasible, showing enhanced P2Y12 inhibition with DAPT and reduced TG with DPI, with no differences in platelet-mediated global thrombogenicity between DPI and ticagrelor- and prasugrel-, but not clopidogrel-, based DAPT.

CLINICAL TRIAL REGISTRATION

 http://www.

CLINICALTRIALS

gov Unique Identifier: NCT04006288.

Utilization of P2Y12 Inhibitors in Older Adults With ST-Elevation Myocardial Infarction and Frailty

Choosing optimal P2Y12 inhibitor in frail older adults is challenging because they are at increased risk of both ischemic and bleeding events. We conducted a retrospective cohort study of Medicare Advantage Plan beneficiaries who were prescribed clopidogrel, prasugrel, or ticagrelor after percutaneous coronary intervention-treated ST-elevation myocardial infarction from January 1, 2010 to December 31, 2020. Frailty was defined using claims-based frailty index ≥0.25. We conducted multivariable logistic regression to identify factors associated with using potent P2Y12 inhibitors and multivariable-adjusted competing risk analyses to compare the rate of discontinuation of potent P2Y12 inhibitors in frail versus non-frail patients. There were 11,239 patients (mean age 74 years, 39% women). The prevalence of cardiovascular and geriatric co-morbidities was as follows: 32% chronic kidney disease, 28% heart failure, 10% previous myocardial infarction, 6% dementia, 20% anemia, and 12% frailty. The proportion of patients receiving clopidogrel decreased from 78.3% in 2010 to 2013 to 42.1% in 2018 to 2020, with a concurrent increase in those receiving potent P2Y12 inhibitors (mostly ticagrelor) from 21.7% to 57.9%. Frailty was independently associated with reduced odds of initiation (odds ratio 0.78, 95% confidence interval 0.67 to 0.90) but not with discontinuation of potent P2Y12 inhibitors (subdistribution hazard ratio 1.09, 95% confidence interval 0.98 to 1.22). In conclusion, frail older adults are less likely to receive potent P2Y12 inhibitors after percutaneous coronary intervention-treated ST-elevation myocardial infarction, but they are as likely as non-frail patients to continue with the prescribed P2Y12 inhibitor.

Switching From Cangrelor to Prasugrel in Patients Undergoing Percutaneous Coronary Intervention: The Switching Antiplatelet-6 (SWAP-6) Study

BACKGROUND

A drug-drug interaction (DDI) may occur when transitioning from intravenous P2Y12 inhibition with cangrelor to oral P2Y12 inhibition with prasugrel. However, this has never been tested in patients undergoing percutaneous coronary intervention (PCI).

OBJECTIVES

This study sought to rule out a DDI when cangrelor and prasugrel are concomitantly administered in PCI patients.

METHODS

SWAP-6 (Switching Antiplatelet-6) was a prospective, randomized, 3-arm, open-label pharmacokinetic (PK) and pharmacodynamic (PD) study. Patients (N = 77) were randomized to 1) prasugrel only at the start of PCI, 2) cangrelor plus prasugrel concomitantly at the start of PCI, or 3) cangrelor at the start of PCI plus prasugrel at the end of infusion. Cangrelor infusion was maintained for 2 hours. PK/PD assessments were performed at baseline and 6 time points postrandomization. The primary endpoint was noninferiority in VerifyNow (Werfen) P2Y12 reaction units measured at 4 hours after randomization between cangrelor plus prasugrel concomitantly administered vs prasugrel only. PK assessments included plasma levels of the active metabolite of prasugrel.

RESULTS

Compared with prasugrel, cangrelor further enhances P2Y12 inhibitory effects. At 4 hours postrandomization, P2Y12 reaction unit levels were significantly lower with prasugrel only compared to cangrelor and prasugrel concomitantly administered (least squares means difference = 130; 95% CI: 85-176), failing to meet the prespecified noninferiority margin. Findings were corroborated by multiple PD assays. The active metabolite of prasugrel levels were not affected by concomitant administration of cangrelor and were low at the end of cangrelor infusion.

CONCLUSIONS

In patients undergoing PCI, concomitant administration of prasugrel with cangrelor leads to a marked increase in platelet reactivity after stopping cangrelor infusion, supporting the presence of a DDI. (Switching Antiplatelet Therapy-6 [SWAP-6]; NCT04668144).

Single-antiplatelet regimen in ruptured cerebral blood blister and dissecting aneurysms treated with flow-diverter stent reconstruction

BACKGROUND

Flow diversion treatment of ruptured cerebral aneurysms remains challenging due to the need for double-antiplatelet therapy. We report our experience with flow-diverter stent (FDS) reconstruction with single-antiplatelet therapy of ruptured cerebral blood blister and dissecting aneurysms.

METHODS

In this case series we performed a retrospective analysis of all patients with ruptured cerebral aneurysms who were treated with a phosphoryl-bonded FDS between 2019 and 2022 in a single center. Periprocedurally, all patients received weight-adapted eptifibatide IV and heparin IV. After 6-24 hours, eptifibatide was switched to oral prasugrel as monotherapy. We analyzed the rate of bleeding complications, thromboembolic events, occlusion rate and clinical outcome.

RESULTS

Nine patients with subarachnoid hemorrhage were treated, eight within 24 hours of symptom onset. Seven patients were treated with one FDS and two patients received two FDS in a telescopic fashion. Two aneurysms were additionally coil embolized. Fatal re-rupture occurred in one case; eight patients survived and had no adverse events associated with the FDS. Six patients showed complete occlusion of the aneurysm after 3 months (n=2) and 1 year (n=4), respectively. Two patients showed subtotal occlusion of the aneurysm at the last follow-up after 3 months and 6 months, respectively. Favorable clinical outcome was achieved in five patients.

CONCLUSIONS

Peri-interventional single-antiplatelet therapy with eptifibatide followed by prasugrel was sufficient to prevent thromboembolic events and reduce re-bleeding using an anti-thrombogenic FDS. FDS with single-antiplatelet therapy might be a viable option for ruptured blood blister and dissecting cerebral aneurysms.

Structural characterization of the optical isomers esomeprazole and omeprazole using the JADER and FAERS databases

BACKGROUND

It is unclear whether the s (-) form of esomeprazole (EPZ) has an improved safety profile when compared with its racemic form omeprazole (OPZ). We assessed the potential complications of these optical isomers when combined with cilostazol, clopidogrel, and prasugrel, which are frequently used concomitant medications.

METHODS

Using two adverse event spontaneous reporting databases, Japanese Adverse Drug Event Report (JADER) and FDA Adverse Event Reporting System (FAERS), adverse event names for hemorrhage, venous/arterial embolization, and thrombus were obtained from the Medical Dictionary for Regulatory Activities. Reported odds ratios were calculated using a 2 × 2 contingency table, and a signal was considered present if the lower limit of the 95% confidence interval was >1.

RESULTS

In combination with cilostazol, a hemorrhagic signal for OPZ in JADER and arterial emboli and thrombus signals for EPZ were detected in both databases. In combination with clopidogrel, OPZ showed arterial emboli and thrombus signals in JADER and venous/arterial emboli and thrombus signals in FAERS, while EPZ displayed arterial emboli and thrombus signals in FAERS. In contrast, when in combination with prasugrel, there were no adverse event signals in either database.

CONCLUSION

This study has confirmed using big data, that EPZ, the optical isomer and racemic form of omeprazole, has the beneficial characteristics of being less sensitive to CYP, as was intended by its design.

Single antiplatelet therapy directly after percutaneous coronary intervention in non-ST-segment elevation acute coronary syndrome patients: the OPTICA study

BACKGROUND

Early P2Y12 inhibitor monotherapy has emerged as a promising alternative to 12 months of dual antiplatelet therapy following percutaneous coronary intervention (PCI).

AIMS

In this single-arm pilot study, we evaluated the feasibility and safety of ticagrelor or prasugrel monotherapy directly following PCI in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS).

METHODS

Patients received a loading dose of ticagrelor or prasugrel before undergoing platelet function testing and subsequent PCI using new-generation drug-eluting stents. The stent result was adjudicated with optical coherence tomography in the first 35 patients. Ticagrelor or prasugrel monotherapy was continued for 12 months. The primary ischaemic endpoint was the composite of all-cause mortality, myocardial infarction, definite or probable stent thrombosis or stroke within 6 months. The primary bleeding endpoint was Bleeding Academic Research Consortium type 2, 3 or 5 bleeding within 6 months.

RESULTS

From March 2021 to March 2022, 125 patients were enrolled, of whom 75 ultimately met all in- and exclusion criteria (mean age 64.5 years, 29.3% women). Overall, 70 out of 75 (93.3%) patients were treated with ticagrelor or prasugrel monotherapy directly following PCI. The primary ischaemic endpoint occurred in 3 (4.0%) patients within 6 months. No cases of stent thrombosis or spontaneous myocardial infarction occurred. The primary bleeding endpoint occurred in 7 (9.3%) patients within 6 months.

CONCLUSIONS

This study provides first-in-human evidence that P2Y12 inhibitor monotherapy directly following PCI for NSTE-ACS is feasible, without any overt safety concerns, and highlights the need for randomised controlled trials comparing direct P2Y12 inhibitor monotherapy with the current standard of care.

Bleeding risk in patients prescribed dual antiplatelet therapy and triple therapy after coronary interventions: the ADAPTT retrospective population-based cohort studies

Background

Bleeding among populations undergoing percutaneous coronary intervention or coronary artery bypass grafting and among conservatively managed patients with acute coronary syndrome exposed to different dual antiplatelet therapy and triple therapy (i.e. dual antiplatelet therapy plus an anticoagulant) has not been previously quantified.

Objectives

The objectives were to estimate hazard ratios for bleeding for different antiplatelet and triple therapy regimens, estimate resources and the associated costs of treating bleeding events, and to extend existing economic models of the cost-effectiveness of dual antiplatelet therapy.

Design

The study was designed as three retrospective population-based cohort studies emulating target randomised controlled trials.

Setting

The study was set in primary and secondary care in England from 2010 to 2017.

Participants

Participants were patients aged ≥ 18 years undergoing coronary artery bypass grafting or emergency percutaneous coronary intervention (for acute coronary syndrome), or conservatively managed patients with acute coronary syndrome.

Data sources

Data were sourced from linked Clinical Practice Research Datalink and Hospital Episode Statistics.

Interventions

Coronary artery bypass grafting and conservatively managed acute coronary syndrome: aspirin (reference) compared with aspirin and clopidogrel. Percutaneous coronary intervention: aspirin and clopidogrel (reference) compared with aspirin and prasugrel (ST elevation myocardial infarction only) or aspirin and ticagrelor.

Main outcome measures

Primary outcome: any bleeding events up to 12 months after the index event. Secondary outcomes: major or minor bleeding, all-cause and cardiovascular mortality, mortality from bleeding, myocardial infarction, stroke, additional coronary intervention and major adverse cardiovascular events.

Results

The incidence of any bleeding was 5% among coronary artery bypass graft patients, 10% among conservatively managed acute coronary syndrome patients and 9% among emergency percutaneous coronary intervention patients, compared with 18% among patients prescribed triple therapy. Among coronary artery bypass grafting and conservatively managed acute coronary syndrome patients, dual antiplatelet therapy, compared with aspirin, increased the hazards of any bleeding (coronary artery bypass grafting: hazard ratio 1.43, 95% confidence interval 1.21 to 1.69; conservatively-managed acute coronary syndrome: hazard ratio 1.72, 95% confidence interval 1.15 to 2.57) and major adverse cardiovascular events (coronary artery bypass grafting: hazard ratio 2.06, 95% confidence interval 1.23 to 3.46; conservatively-managed acute coronary syndrome: hazard ratio 1.57, 95% confidence interval 1.38 to 1.78). Among emergency percutaneous coronary intervention patients, dual antiplatelet therapy with ticagrelor, compared with dual antiplatelet therapy with clopidogrel, increased the hazard of any bleeding (hazard ratio 1.47, 95% confidence interval 1.19 to 1.82), but did not reduce the incidence of major adverse cardiovascular events (hazard ratio 1.06, 95% confidence interval 0.89 to 1.27). Among ST elevation myocardial infarction percutaneous coronary intervention patients, dual antiplatelet therapy with prasugrel, compared with dual antiplatelet therapy with clopidogrel, increased the hazard of any bleeding (hazard ratio 1.48, 95% confidence interval 1.02 to 2.12), but did not reduce the incidence of major adverse cardiovascular events (hazard ratio 1.10, 95% confidence interval 0.80 to 1.51). Health-care costs in the first year did not differ between dual antiplatelet therapy with clopidogrel and aspirin monotherapy among either coronary artery bypass grafting patients (mean difference £94, 95% confidence interval -£155 to £763) or conservatively managed acute coronary syndrome patients (mean difference £610, 95% confidence interval -£626 to £1516), but among emergency percutaneous coronary intervention patients were higher for those receiving dual antiplatelet therapy with ticagrelor than for those receiving dual antiplatelet therapy with clopidogrel, although for only patients on concurrent proton pump inhibitors (mean difference £1145, 95% confidence interval £269 to £2195).

Conclusions

This study suggests that more potent dual antiplatelet therapy may increase the risk of bleeding without reducing the incidence of major adverse cardiovascular events. These results should be carefully considered by clinicians and decision-makers alongside randomised controlled trial evidence when making recommendations about dual antiplatelet therapy.

Limitations

The estimates for bleeding and major adverse cardiovascular events may be biased from unmeasured confounding and the exclusion of an eligible subgroup of patients who could not be assigned an intervention. Because of these limitations, a formal cost-effectiveness analysis could not be conducted.

Future work

Future work should explore the feasibility of using other UK data sets of routinely collected data, less susceptible to bias, to estimate the benefit and harm of antiplatelet interventions.

Trial registration

This trial is registered as ISRCTN76607611.

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 8. See the NIHR Journals Library website for further project information.

Pharmacogenetics of P2Y12 receptor inhibitors

Oral P2Y12 inhibitors are commonly prescribed for cardiovascular disease and include clopidogrel, prasugrel, and ticagrelor. Each of these drugs has its strengths and weaknesses. Prasugrel and ticagrelor are more potent inhibitors of platelet aggregation and were shown to be superior to clopidogrel in preventing major adverse cardiovascular events after an acute coronary syndrome and percutaneous coronary intervention (PCI) in the absence of genotyping. However, both are associated with an increased risk for non-coronary artery bypass-related bleeding. Clopidogrel is a prodrug requiring bioactivation, primarily via the CYP2C19 enzyme. Approximately 30% of individuals have a CYP2C19 no function allele and decreased or no CYP2C19 enzyme activity. Clopidogrel-treated carriers of a CYP2C19 no function allele have decreased exposure to the clopidogrel active metabolite and lesser inhibition of platelet aggregation, which likely contributed to reduced clopidogrel efficacy in clinical trials. The pharmacogenetic data for clopidogrel are most robust in the setting of PCI, but evidence is accumulating for other indications. Guidance is available from expert consensus groups and regulatory agencies to assist with integrating genetic information into P2Y12 inhibitor prescribing decisions, and CYP2C19 genotype-guided antiplatelet therapy after PCI is one of the most common examples of clinical pharmacogenetic implementation. Herein, we review the evidence for pharmacogenetic associations with clopidogrel response and outcomes with genotype-guided P2Y12 inhibitor selection and describe guidance to assist with pharmacogenetic implementation. We also describe processes for applying genotype data for P2Y12 inhibitor therapy selection and remaining gaps in the field. Ultimately, consideration of both clinical and genetic factors may guide selection of P2Y12 inhibitor therapy that optimally balances the atherothrombotic and bleeding risks.

Survey of clinical practice pattern in Germany's certified chest pain units : Adherence to the European Society of Cardiology guidelines on non-ST-segment elevation acute coronary syndrome

BACKGROUND

We aimed to analyze the 2020 standard of care in certified German chest pain units (CPU) with a special focus on non-ST-segment elevation acute coronary syndrome (NSTE-ACS) through a voluntary survey obtained from all certified units, using a prespecified questionnaire.

METHODS

The assessment included the collection of information on diagnostic protocols, risk assessment, management and treatment strategies in suspected NSTE-ACS, the timing of invasive therapy in non-ST-segment elevation myocardial infarction (NSTEMI), and the choice of antiplatelet therapy.

RESULTS

The response rate was 75%. Among all CPUs, 77% are currently using the European Society of Cardiology (ESC) 0/3‑h high-sensitive troponin protocol, and only 20% use the ESC 0/1‑h high-sensitive troponin protocol as a default strategy. Conventional ergometry is still the commonly performed stress test with a utilization rate of 47%. Among NSTEMI patients, coronary angiography is planned within 24 h in 96% of all CPUs, irrespective of the day of the week. Prasugrel is the P2Y12 inhibitor of choice in ST-segment elevation myocardial infarction (STEMI), but despite the impact of the ISAR-REACT 5 trial on selection of antiplatelet therapy, ticagrelor is still favored over prasugrel in NSTE-ACS. If triple therapy is used in NSTE-ACS with atrial fibrillation, it is maintained up to 4 weeks in 51% of these patients.

CONCLUSION

This survey provides evidence that Germany's certified CPUs ensure a high level of guideline adherence and quality of care. The survey also identified areas in need of improvement such as the high utilization rate of stress electrocardiogram (ECG).

Temporal patterns, characteristics, and predictors of clinical outcomes in patients undergoing percutaneous coronary intervention for stent thrombosis

BACKGROUND

There are limited data on the outcomes of percutaneous coronary intervention (PCI) following stent thrombosis (ST) and differences exist based on timing.

AIMS

Our aim was to study the rates of PCI procedures for an ST indication among all patients admitted for PCI at a national level and to compare their characteristics and procedural outcomes based on ST timing.

METHODS

All PCI procedures in England and Wales (2014-2020) were retrospectively analysed and stratified by the presence of ST into four groups: non-ST, early ST (0-30 days), late ST (>30-360 days), very late ST (>360 days). Multivariable logistic regression models were performed to assess the odds ratios (OR) of in-hospital MACCE (major adverse cardiovascular and cerebrovascular events, a composite of mortality, acute stroke and reinfarction) and mortality.

RESULTS

Overall, 7,923 (1.4%) procedures were for ST indication, most commonly for early ST (n=4,171; 52.6%), followed by very late ST (n=2,801; 35.4%) and late ST (n=951; 12.0%). The rate of PCI for ST declined between 2014 and 2020 (1.7 to 1.4%; p<0.001). Early ST was the only subgroup associated with increased odds of MACCE (OR 1.22, 95% CI: 1.05-1.41), all-cause mortality (OR 1.21, 95% CI: 1.07-1.36) and reinfarction (OR 2.48, 95% CI: 1.48-4.14), compared with non-ST indication. The odds of mortality were significantly reduced in ST patients with the use of intravascular imaging (OR 0.66, 95% CI: 0.48-0.92) and newer P2Y12 inhibitors (ticagrelor: OR 0.69, 95% CI: 0.49-0.95; prasugrel: OR 0.54, 95% CI: 0.30-0.96).

CONCLUSIONS

PCI for ST has declined in frequency over a 7-year period, with most procedures performed for early ST. Among the different times of ST onset, only early ST is associated with worse clinical outcomes after PCI. Routine use of intravascular imaging and newer P2Y12 inhibitors could further improve outcomes in this high-risk procedural group.

Dual antiplatelet therapy is under-prescribed in patients with surgically treated acute myocardial infarction

OBJECTIVES

Despite guideline recommendations, previous reports, coming mainly from outside Europe, showed low rates of prescriptions for dual antiplatelet therapy (DAPT) in patients with acute myocardial infarction (AMI) undergoing surgical revascularization. The present study assesses this issue in the era of potent P2Y12 inhibitors in Switzerland.

METHODS

All patients with a diagnosis of AMI included in the Acute Myocardial Infarction in Switzerland Plus Registry from January 2014 to December 2019 were screened; 9050 patients undergoing either percutaneous (8727, 96.5%) or surgical (323, 3.5%) revascularization were included in the analysis.

RESULTS

Surgically treated patients were significantly less likely to receive DAPT at discharge (56.3% vs 96.7%; P < 0.001). Even when discharged with a prescription for DAPT, those patients were significantly less likely to receive a regimen containing a new P2Y12 inhibitor (67/182 [36.8%] vs 6945/8440 [83.2%]; P < 0.001). At multivariate analysis, surgical revascularization was independently associated with a lower likelihood of receiving a prescription for DAPT at discharge (odds ratio 0.03, 95% confidence interval 0.02-0.06).

CONCLUSIONS

DAPT prescriptions for patients with AMI undergoing surgical revascularization are not in line with current guideline recommendations. Efforts are necessary to clarify the role of DAPT for secondary prevention in these patients and increase the confidence of treating physicians in guideline recommendations.

CLINICAL TRIAL REGISTRATION

Acute Myocardial Infarction in Switzerland Plus Registry; registration number at ClinicalTrials.gov: NCT01305785.

Expert Opinion on P2Y12 Inhibitors Use in Management of Acute Coronary Syndromes: Focus on Ticagrelor

Ticagrelor is a potent, oral P2Y12 inhibitor used as a part of dual antiplatelet therapy (DAPT) in acute coronary syndromes (ACS). New evidence has emerged for its use in ACS, which may be crucial for the Indian context. This brought together nearly 150 experts in ACS management across the country who reviewed the current evidence and discussed the same through a series of 10 meetings on an online platform. With all experts' agreement, the key expert opinions for the P2Y12 inhibitors use in ACS management were finalized. These include the following. In ACS patients aged &lt;75 years, with diabetes, a history of stroke/transient ischemic attack, and chronic kidney disease, ticagrelor may be preferred over other P2Y12 inhibitors. It may also be preferred in the elderly above 75 years with clopidogrel is a suitable alternative in patients at high-risk of bleeding. Rates of stent thrombosis are lower with ticagrelor than clopidogrel. In patients managed with fibrinolysis, use ticagrelor after 48 hours if streptokinase was the fibrinolytic agent or it can be used after 12 to 24 hours if fibrin-specific fibrinolytic was used. Rates of major bleeding in patients treated with fibrinolysis are similar to clopidogrel. Prehospital administration may be preferred over in-hospital administration with expected bleeding rates similar to clopidogrel. Switching among P2Y12 inhibitors should be done with due consideration of their pharmacodynamics. At present, DAPT should be continued for 12 months with discontinuation after three to six months in patients with high bleeding risk. The use of low dose ticagrelor may be considered in cases with high-bleeding risk. DAPT or ticagrelor continuation beyond one year should be individualized considering ischemic and bleeding risks. Dyspnea is a common, mild, and transient and does not necessitate ticagrelor discontinuation. Severe dyspnea should be investigated thoroughly. In conclusion, ticagrelor (180 mg, 90 mg, and 60 mg doses), a potent antiplatelet is expected to reshape the antiplatelet use in the management of ACS.

Initiation of and persistence with P2Y12 inhibitors in patients with myocardial infarction according to revascularization strategy: a nationwide study

BACKGROUND

We aimed to analyse initiation of and persistence with P2Y12 inhibitors after first-time myocardial infarction (MI).

METHODS AND RESULTS

Using Danish nationwide registries, we identified patients ≥30 years with first-time MI during 1 January 2005-30 June 2016 and subsequent prescriptions of P2Y12 inhibitors. Independent factors related to initiation of and persistence with P2Y12 inhibitors were analysed by multivariable logistic regression and a Cox proportional hazards model. Patients were stratified by revascularization strategy: percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG), or medical therapy alone (MTA). Overall, 79 597 MI patients were included with 39 172 undergoing PCI, 2619 CABG, and 16 640 MTA, showing initiation of P2Y12 inhibitors of 93.4%, 49.0%, and 51.5%, respectively. Congestive heart failure, cerebrovascular disease, cardiac dysrhythmias, renal failure, previous bleeding, and oral anticoagulants were associated with less initiation of P2Y12 inhibitors. Female sex was associated with less initiation of P2Y12 inhibitors following MTA. MTA, coronary angiography, cerebrovascular disease, diabetes with complications, previous bleeding, antidiabetics, and ticagrelor as P2Y12 inhibitor were associated with non-persistence, whereas female sex, advanced age, and concomitant pharmacotherapy with angiotensin-converting enzyme inhibitors, beta-blockers, statins, oral anticoagulants, and aspirin were associated with high persistence.

CONCLUSION

Initiation of P2Y12 inhibitors in PCI-treated MI patients was high in contrast to those treated with CABG or MTA and patients with certain comorbidities. Further studies on the benefit-risk ratio of P2Y12 inhibitors in CABG-treated or MTA-treated patients and patients with comorbidities after first-time MI are warranted, as is focus on persistence among patients receiving MTA, patients with comorbidities, and users of ticagrelor.

Implementing a pharmacogenetic-driven algorithm to guide dual antiplatelet therapy (DAPT) in Caribbean Hispanics: protocol for a non-randomised clinical trial

INTRODUCTION

Minority populations in the USA are disproportionately affected by cardiovascular conditions. Reduced responsiveness to clopidogrel among carriers of CYP2C19 variants has been reported in patients with either coronary artery disease (CAD) or acute coronary syndrome (ACS) after the percutaneous coronary intervention (PCI). Previous studies have evaluated CYP2C19 genotyping-guided antiplatelet therapy in selected populations; however, this has yet to be tested among Hispanics. Given the paucity of clinical research on CYP2C19 and antiplatelet clinical outcomes in Hispanics, our study will test the safety and efficacy of a genetic-driven treatment algorithm to guide dual antiplatelet therapy (DAPT) in Caribbean Hispanics.

METHODS AND ANALYSIS

This is a multicentre, prospective, non-randomised clinical trial that proposes an assessment of pharmacogenomic-guided DAPT in post-PCI Caribbean Hispanic patients with ACS or CAD. We will recruit 250 patients to be compared with a matched non-concurrent cohort of 250 clopidogrel-treated patients (standard-of-care). Major adverse cardiovascular events (MACEs) such as all-cause death, myocardial infarction (MI), stroke, coronary revascularisation, stent thrombosis and bleedings over 6 months will be the study endpoints. Among the recruited, high-risk patients will be escalated to ticagrelor and low-risk patients will remain on clopidogrel. The primary objective is to determine whether genetic-guided therapy is superior to standard of care. The secondary objective will determine if clopidogrel treatment in low-risk patients is not associated with a higher rate of MACEs compared with escalated antiplatelet therapy in high-risk patients. Patients will be enrolled up to the group's completion.

ETHICS AND DISSEMINATION

Approval was obtained from the Institutional Review Board of the University of Puerto Rico Medical Sciences Campus (protocol # A4070417). The study will be carried out in compliance with the Declaration of Helsinki and International Conference on Harmonization Good Clinical Practice Guidelines. Findings will be published in a peer-reviewed journal and controlled access to experimental data will be available.

TRIAL REGISTRATION NUMBER

NCT03419325; Pre-results.

[Duration and Timing of Initiation of Therapy With Platelet P2Y12 Inhibitors in the Treatment of Patients With Acute Coronary Syndrome]

In recent years, the issues of choice of an agent for dual antiplatelet therapy (DAPT) as well as timing of initiation and duration of DAPT in patients with acute coronary syndrome (ACS) have been actively discussed. In this article we present data of major randomized trials of clopidogrel and novel P2Y12 inhibitors - prasugrel, ticagrelor, cangrelor - assessing strategy of administration of antiaggregants in patients with ACS before coronary angiography / percutaneous coronary intervention. The article also contains analysis of differences between recommendations of the European Society of Cardiology and American College of Cardiology/American Heart Association on therapy with oral P2Y12 inhibitors in the management of patients with ACS.

Stereoselective inhibition of human platelet aggregation by R-138727, the active metabolite of CS-747 (Prasugrel, LY640315), a novel P2Y12 receptor inhibitor

CS-747 (Prasugrel, LY640315) is a thienopyridine antiplatelet prodrug that is metabolized to the thiol-containing active metabolite R-138727, which binds to and irreversibly inhibits the platelet P2Y12 ADP receptor. R-138727 is composed of 4 stereoisomers, (R, S)-, (R, R)-, (S, S)-, and (S, R)-isomers (the first letter for the configuration of a chiral center at the sulfur-bearing position and the second for that at the benzylic position). In the present study, we determined the stereoselectivity of P2Y12 antagonist effects by assessing the antagonism of the [3H]-2-MeS-ADP that binds to human P2Y12 receptors expressed in Chinese hamster ovary cells as an affinity assay, and by the inhibition of ADP-induced aggregation of washed human platelets as a functional assay. R-138727 and its 2 components, R-99224, a mixture of (R, S)- and (S, R)-isomers and R-100364, a mixture of (R, R)- and (S, S)-isomers, inhibited [3H]-2-MeS-ADP binding and platelet aggregation. The rank order of potency of these compounds were identical in both assays: R-99224>R-138727>> R-100364. Inhibition of ADP-induced platelet aggregation by R-138727 and R-99224 was concentration- and time-related. In experiments using the 4 single stereo-isomers, all isomers inhibited ADP-induced platelet aggregation, but the (R, S)-isomer was found to be the most potent, followed by the (R, R)-isomer. These in vitro studies indicate that R-138727 is an effective antagonist of P2Y12 and potent inhibitor of ADP-induced platelet aggregation, and that these antiplatelet activities of R-138727 are largely dependent on its (R, S)-isomer. This suggests that the (R)- configuration of the reactive thiol group of the active metabolite of CS-747 is critical for P2Y12 and platelet inhibitory activities.

Survival After Solid Cancers in Antithrombotic Trials

The impact of antithrombotics on cancer is currently under intense investigation because of the excess of solid cancers in trials after thienopyridines such as TRITON (prasugrel), DAPT (prasugrel and clopidogrel), PAR-1 thrombin antagonist in TRACER (vorapaxar), pyrimidines in PEGASUS (ticagrelor), and in APPRAISE-2 after apixaban. However, whether patient survival after solid cancer (SASC) in antithrombotic trials may be affected is unknown. We matched the 1-year SASC rate in antithrombotic trials reported by Food and Drug Administration with the census averages in Surveillance, Epidemiology, and End Results (SEER) Program by the US National Cancer Institute and World Health Organization (WHO) surveys. The Food and Drug Administration provided the SASC data for 3 trials with similar cancer survival of about 70% for the first year of follow-up in TRITON, APPRAISE-2, and ARISTOTEL. Adjusted cancers in TRITON with SEER (odds ratio 0.92; 95% confidence interval 0.53 to 1.59, p = 0.4351) and WHO (odds ratio 0.99; 95% confidence interval 0.57 to 1.7, p = 1.00) revealed very close if not identical SASC rates in antithrombotic trials compared to epidemiologic census estimates. In conclusion, SASC rates in patients enrolled in antithrombotic trials do not differ from SEER or World Health Organization averages.

Meta-Analysis of Comparison of the Newer Oral P2Y12 Inhibitors (Prasugrel or Ticagrelor) to Clopidogrel in Patients With Non-ST-Elevation Acute Coronary Syndrome

Newer oral P2Y12 inhibitors are more potent and have faster onset of action than clopidogrel. However, the efficacy and safety in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) are not well studied. A systemic search of MEDLINE and EMBASE databases was performed to identify randomized clinical trials comparing newer oral P2Y12 inhibitors (prasugrel or ticagrelor) to clopidogrel in patients with NSTE-ACS. The primary outcome was a composite of cardiovascular death, myocardial infarction (MI), and stroke (major cardiovascular events [MACE]). Secondary outcomes were individual components of the primary outcome, all-cause mortality, and Thrombolysis In Myocardial Infarction (TIMI) major and minor bleeding. A total of 31,470 patients with NSTE-ACS from 4 randomized clinical trials were included (newer oral P2Y12 inhibitors: 15,951; clopidogrel: 15,519). Newer oral P2Y12 inhibitors significantly decreased MACE (relative risk [RR] 0.87, 95% confidence interval [CI] 0.80 to 0.95) and MI (RR 0.85, 95% CI 0.75 to 0.96) and showed a trend toward reduction of cardiovascular death (RR 0.89, 95% CI 0.71 to 1.01). There was a significant increase in TIMI major bleeding (RR 1.27, 95% CI 1.07 to 1.50) and TIMI major or minor bleeding (RR 1.20, 95% CI 1.02 to 1.42). Results were largely similar when stratified by ticagrelor versus prasugrel (pinteraction >0.05) except for increased TIMI major/minor bleeding with prasugrel than ticagrelor (pinteraction = 0.01). In conclusion, in patients with NSTE-ACS, newer oral P2Y12 inhibitors decrease MACE and MI at the expense of a significant increase in the risk of bleeding. Treatment of 1,000 patients with newer oral P2Y12 inhibitors will prevent 16 MACE and 13 MIs at the expense of increase in 6 major bleeding events.

Meta-Analysis of Randomized Controlled Trials Comparing Risk of Major Adverse Cardiac Events and Bleeding in Patients With Prasugrel Versus Clopidogrel

The use of prasugrel in patients with coronary artery disease (CAD) has been associated with decreased major adverse cardiac events (MACEs) compared with clopidogrel but with an increased risk of bleeding. However, it remains unclear if the risks of bleeding outweigh those of MACEs in patients on prasugrel treatment. We systematically reviewed randomized controlled trials comparing prasugrel with clopidogrel in patients with CAD. We performed a literature search of PubMed, EMBASE, and Cochrane Central Register of Controlled Trial databases from inception to November 25, 2014, and reviewed the reference lists of retrieved articles. A comparative estimate was made for the combined rates of MACEs and bleeding from the same trials in the framework of this meta-analysis and expressed as odds ratios (ORs) and 95% confidence intervals (CIs) in both random- and fixed-effects models. Nine studies involving 25,214 patients were included in our meta-analysis. In both the random- and fixed-effects models, the risks of MACEs outweighed those of major bleeding (OR 7.48, 95% CI 3.75 to 14.94, p <0.0001, random effects) and of minor bleeding (OR 3.77, 95% CI 1.73 to 8.22, p = 0.009, random effects). Results were corroborated in a standard-dose clopidogrel subgroup analysis (OR 7.46, 95% CI 3.54 to 15.68, p <0.0001, and OR 6.44, 95% CI 2.80 to 14.80, p <0.0001, random effects, respectively). In conclusion, despite the increased risk of bleeding associated with prasugrel treatment compared with clopidogrel, the risk of MACEs far outweighed the risk of bleeding.

Clinical evidence for oral antiplatelet therapy in acute coronary syndromes

Platelet-mediated thrombosis is a major pathophysiological mechanism that underlies acute coronary syndromes, and therefore, antiplatelet therapy is an important foundation in the treatment and prevention of recurrence of these syndromes. Nearly 30 years ago, aspirin was the first agent to show a benefit for acute coronary syndromes and is still a key therapeutic agent. The landmark CURE trial showed that the addition of a P2Y12 antagonist, clopidogrel, to aspirin was beneficial in the treatment of acute coronary syndromes. Despite substantial benefits with clopidogrel, limitations include the slow speed of onset, variable response, and a modest antiplatelet effect. Next-generation P2Y12 antagonists, prasugrel and ticagrelor, overcome these limitations and have been shown, in large-scale clinical trials for acute coronary syndromes, to reduce ischaemic events more than clopidogrel, at the expense of an increase in bleeding. Additional agents that target platelets by alternate mechanisms, including the protease-activated receptor-1 antagonist vorapaxar, have shown ischaemic benefit. These large-scale trials inform treatment decisions that need to balance ischaemic benefit and bleeding risk in patients with acute coronary syndromes. This Series paper describes major trial results, implications for clinical practice, and summarises continuing controversy.

Predictors of high on-aspirin platelet reactivity in high-risk vascular patients treated with single or dual antiplatelet therapy

Aspirin is the key treatment in the secondary prevention of atherothrombosis. Interindividual variability of response has been linked to a higher risk for ischemic events. The aim of this study was to identify clinical and biologic factors predicting high on-aspirin platelet reactivity (HPR) in a high-risk, "real-world" population of vascular patients. All platelet testing performed from 2011 to 2013 in consecutive patients receiving long-term treatment with aspirin for coronary or cerebrovascular disease was retrospectively analyzed. Indications for platelet testing were recurrent ischemic events or high-risk angioplasty. HPR was defined as aggregation intensity≥20% using light-transmission aggregometry with arachidonic acid 0.5 mg/ml. Collagen-epinephrine platelet function analysis was also performed (threshold<165 seconds). Cardiovascular risk factors, usual biologic parameters, and antiplatelet treatment were recorded. A total of 1,508 patients were included (mean age 63 years, 71% men, 23% with diabetes). Antiplatelet treatment was aspirin alone in 333 patients and dual-antiplatelet therapy in 1,175 patients. HPR was found in 11.1% of patients. In multivariate analysis, independent predictive factors of HPR on light-transmission aggregometry with arachidonic acid were diabetes mellitus (odds ratio [OR] 2.10, 95% confidence interval [CI] 1.39 to 3.16), age (OR 1.25, 95% CI 1.06 to 1.47), fibrinogen level (OR 1.20, 95% CI 1.02 to 1.42), and von Willebrand factor level (OR 1.06, 95% CI 1.03 to 1.09). On light-transmission aggregometry with arachidonic acid and collagen-epinephrine platelet function analysis, fibrinogen remained the main factor associated with HPR (OR 1.33, 95% CI 1.19 to 1.61). Similar results were found in patients treated with aspirin alone or dual-antiplatelet therapy. A fibrinogen level>4.0 g/L was associated with a 3.9-fold increased risk for HPR in patients aged <75 years. In conclusion, fibrinogen level was the major predictor of HPR on aspirin in this large population of high-risk vascular patients.

ELECTIVE PERCUTANEOUS CORONARY INTERVENTIONS--A COMPARISION OF EFFICACY OF CLOPIDOGREL AND PRASUGREL

BACKGROUND

Percutaneous coronary interventions are almost always preceded by the loading dose of platelets inhibiter drugs such as clopidogrel or prasugrel and followed by maintenance therapy to decrease the mortality and morbidity due to stent thrombosis. This study was conducted to compare the efficacy of clopidogrel and prasugrel for inhibiting platelet aggregation among patients undergoing elective percutaneous coronary intervention.

METHODS

This randomized controlled trial study was done in Department of Cardiology, Postgraduate Medical Institute Govt. Lady Reading Hospital Peshawar. A total of 148 patients were randomly allocated to either group-A containing 74 patients using clopidogrel or group-B containing 74 patients using prasugrel

RESULTS

Group-A had 55 (74.3%) male and 19 (25.7%) females while group-B had 56(75.7%) males and 18 (24.3%) females (p=0.85). Mean age was 54.9 +/- 11.2 years in group-A and was 57.7 +/- 8.7 years in group-B (p=0.09). Mean body weight was 71.8?6.4 Kg in group-A and 70.8 +/- 6.3 Kg in group-B (p=0.35). Mean Baseline platelet aggregation before drug administration was 10.43 +/- 1.9 ohm in group-A while 10.12 +/- 2.2 ohm in group-B (p=0.36). Mean Follow up platelet aggregation 6 hours after drug administration was 5.88 +/- 2.9 in group-A while it was 3.47 +/- 1.8 ohm in group-B (p=0.001). Mean Difference between basal and follow up platelet aggregation +/-SD was 52.9649 +/- 24.77 in group-A while it was 82.25 +/- 14.34 in group-B (p=0.001). 63(85.15%) of group-A had inhibition of platelets aggregation >10% as compare to 72(97.3%) of group-B had inhibition of platelets aggregation >10% (p=0.009).

CONCLUSION

Prasugrel is more efficacious than clopidogrel in term of inhibition of platelets aggregation.

Twelve or 30 months of dual antiplatelet therapy after drug-eluting stents

BACKGROUND

Dual antiplatelet therapy is recommended after coronary stenting to prevent thrombotic complications, yet the benefits and risks of treatment beyond 1 year are uncertain.

METHODS

Patients were enrolled after they had undergone a coronary stent procedure in which a drug-eluting stent was placed. After 12 months of treatment with a thienopyridine drug (clopidogrel or prasugrel) and aspirin, patients were randomly assigned to continue receiving thienopyridine treatment or to receive placebo for another 18 months; all patients continued receiving aspirin. The coprimary efficacy end points were stent thrombosis and major adverse cardiovascular and cerebrovascular events (a composite of death, myocardial infarction, or stroke) during the period from 12 to 30 months. The primary safety end point was moderate or severe bleeding.

RESULTS

A total of 9961 patients were randomly assigned to continue thienopyridine treatment or to receive placebo. Continued treatment with thienopyridine, as compared with placebo, reduced the rates of stent thrombosis (0.4% vs. 1.4%; hazard ratio, 0.29 [95% confidence interval {CI}, 0.17 to 0.48]; P<0.001) and major adverse cardiovascular and cerebrovascular events (4.3% vs. 5.9%; hazard ratio, 0.71 [95% CI, 0.59 to 0.85]; P<0.001). The rate of myocardial infarction was lower with thienopyridine treatment than with placebo (2.1% vs. 4.1%; hazard ratio, 0.47; P<0.001). The rate of death from any cause was 2.0% in the group that continued thienopyridine therapy and 1.5% in the placebo group (hazard ratio, 1.36 [95% CI, 1.00 to 1.85]; P=0.05). The rate of moderate or severe bleeding was increased with continued thienopyridine treatment (2.5% vs. 1.6%, P=0.001). An elevated risk of stent thrombosis and myocardial infarction was observed in both groups during the 3 months after discontinuation of thienopyridine treatment.

CONCLUSIONS

Dual antiplatelet therapy beyond 1 year after placement of a drug-eluting stent, as compared with aspirin therapy alone, significantly reduced the risks of stent thrombosis and major adverse cardiovascular and cerebrovascular events but was associated with an increased risk of bleeding. (Funded by a consortium of eight device and drug manufacturers and others; DAPT ClinicalTrials.gov number, NCT00977938.).

[Anticoagulant therapy in secondary prevention of coronary events]

Secondary prevention of atherothrombotic events is the domain of antiplatelet therapy and according to present risk is used one drug strategy or combination of acetylsalicylic acid with ADP receptor blockers. The importance of the combination of dual antiplatelet therapy together with xabans or dabigatran was investigated in 6 clinical trials. Only one of them (ATLAS ACS 2-TIMI 51) indicated that treatment with small dose of rivaroxaban (2 × 2.5 mg) may be added to dual strategy of acetylsalicylic acid and clopidogrel. The risk of major bleeding event is increased and net clinical benefit is only about 0.5 % per year. Dual therapy with aspirin and prasugrel or tikagrelor is beneficial. In the second part of the review is discussed higher incidence of myocardial infarction in controlled group in the trial comparing treatment of dabigatran with warfarin. This relationship has not been resolved, however, in patients with higher risk of coronary events and indication of anticoagulant treatment with direct oral anticoagulants it is recommended to choose from xabans (apixaban and rivaroxaban).

Real-world observations with prasugrel compared to clopidogrel in acute coronary syndrome patients treated with percutaneous coronary intervention in the United States

OBJECTIVES

To compare 30 and 90 day real-world acute myocardial infarction (AMI) and bleeding related rehospitalization rates in acute coronary syndrome (ACS) patients receiving percutaneous coronary intervention (PCI; ACS-PCI) treated with clopidogrel or prasugrel.

RESEARCH DESIGN AND METHODS

Using the Premier hospital database, ACS-PCI patients receiving a drug-eluting (DES) or bare-metal (BMS) stent and clopidogrel or prasugrel from July 2009 to June 2011 were analyzed. Patients were included based on the prasugrel US prescribing information (USPI), excluding patients with a history of transient ischemic attack/stroke and patients ≥75 years without diabetes or prior MI. The primary endpoint was 30 day adjusted AMI rehospitalization rate. Secondary endpoints included 90 day AMI and 30 and 90 day bleeding-related rehospitalization rates. Treatment comparisons were adjusted using propensity score stratification.

RESULTS

At the index event, prasugrel patients (N = 9404) differed from clopidogrel patients (N = 74,163) by having a lower risk of comorbid conditions associated with bleeding, being more likely younger and male, having ST-elevation MI and receiving a DES. For clopidogrel and prasugrel, respectively, the observed AMI-related rehospitalization rates were 4.7% and 3.9% at 30 days (p < 0.0001) and 6.3% and 5.1% at 90 days (p < 0.0001). After adjustment, prasugrel was associated with ∼10% lower odds of AMI-related rehospitalization (30 days: OR = 0.892 [95% CI: 0.798, 0.998]; 90 days, OR = 0.901 [95% CI: 0.817, 0.994]). Adjusted bleeding-related rehospitalization rates were similar to each other (OR = 1.035 at 30 days [95% CI: 0.765, 1.399]; OR = 0.922 at 90 days [95% CI: 0.725, 1.172]).

STUDY LIMITATIONS

Treatment adherence was not assessed. Bleeding events not resulting in a hospitalization (e.g. office, outpatient, or emergency room visits), deaths outside the hospital, or readmissions to a hospital outside of the Premier alliance were not captured in the database.

CONCLUSIONS

The different patient characteristics between prasugrel- and clopidogrel-treated patients suggest physicians are more selective in choosing patients for prasugrel than recommended in the prasugrel USPI. However, after adjustment for these differences, 30 and 90 day AMI rehospitalization rates were lower for prasugrel-treated patients compared to clopidogrel-treated patients, with no difference in adjusted bleeding-related rehospitalization rates.

Platelet function monitoring in elderly patients on prasugrel after stenting for an acute coronary syndrome: design of the randomized antarctic study

BACKGROUND

Elderly patients are at high risk for both ischemic and bleeding events. Platelet monitoring offers the opportunity to individualized antiplatelet therapy to optimize the therapeutic risk/benefit ratio.

STUDY DESIGN

The ANTARCTIC study is designed to demonstrate the superiority of a strategy of platelet function monitoring with dose and drug adjustment in patients initially on prasugrel 5 mg as compared with a more conventional strategy using prasugrel 5 mg without monitoring and without adjustment (Conventional Treatment Arm) to reduce the primary end point evaluated 1 year after stent percutaneous coronary intervention in elderly patients presenting with an acute coronary syndrome (ACS). ANTARCTIC is a multicenter, prospective, open-label study with 2 parallel arms. A total of 852 elderly patients (≥ 75 years) undergoing stent percutaneous coronary intervention for ACS are to be enrolled. The primary end point is the time to first occurrence of cardiovascular death, myocardial infarction, stroke, definite stent thrombosis, urgent revascularization, and bleeding complications (Bleeding Academic Research Consortium definition 2, 3, or 5). Platelet function analyses will be performed 14 days after randomization and repeated 14 days later in patients who require a change in treatment.

CONCLUSION

ANTARCTIC is a nationwide, prospective, open-label study testing a strategy of platelet function monitoring with dose and drug adjustment to reduce ischemic and bleeding complications in elderly ACS patients undergoing coronary stenting.

An analysis of TRITON-TIMI 38, based on the 12 month recommended length of therapy in the European label for prasugrel

BACKGROUND

In TRITON-TIMI 38, patients with acute coronary syndromes were treated with prasugrel or clopidogrel, with aspirin, for a median of 14.5 (maximum of 15) months. Based on this trial, the EU label for prasugrel recommends treatment for up to 12 months and excludes patients with prior stroke/transient ischemic attack (TIA). Furthermore, the EU label recommends the 10 mg maintenance dose (MD) for patients with body weight ≥60 kg and age <75 years. A lower MD of 5 mg is recommended for those with body weight <60 kg; although generally not recommended, 5 mg can be prescribed to patients ≥75 years after individual risk-benefit evaluation. This paper presents the one-year outcome data for this '10 mg indicated cohort'.

METHODS AND RESULTS

From the overall cohort of 13,608 patients in TRITON-TIMI 38, 10,804 fulfilled inclusion criteria for the 10 mg indicated cohort, of whom 22% had a history of diabetes, 73% an index diagnosis of unstable angina/non-ST-segment-elevation myocardial infarction (UA/NSTEMI), and 27% an index diagnosis of ST-segment-elevation myocardial infarction (STEMI). In this cohort at 12 months, those given prasugrel experienced significantly fewer ischemic events (cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke, 7.8% vs 10.5%, hazard ratio (HR) = 0.73, p < 0.001, than those given clopidogrel, with a non-significant increase in non-coronary artery bypass graft (CABG) TIMI major bleeding, 1.7% vs 1.5%, HR = 1.15, p = 0.40; similarly, in the overall cohort these frequencies were 9.4% vs 11.4%, HR = 0.81, p < 0.001, for cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke, and 2.2% vs 1.8%, HR = 1.24, p = 0.10, for non-CABG TIMI major bleeding. There was a significant reduction in stent thrombosis in the prasugrel group, with similar mortality rates and no excess of strokes.

CONCLUSIONS

Treatment with prasugrel according to EU label recommendations results in a significant 27% and 57% relative risk reduction (absolute risk reductions of 2.7% and 1.2%) in ischemic events and stent thromboses respectively compared with clopidogrel, with a 15% relative risk increase (absolute risk increase of 0.2%) for major bleeds (p = 0.40), and no excess of strokes.

LIMITATIONS

Although restricted to 365 days of follow-up, this analysis encapsulates 1366 of 1424 (95.9%) of all primary endpoint events and 244 of 257 (94.9%) of all first non-CABG TIMI major bleeds reported in the pivotal manuscript. Furthermore, the 10 mg indicated cohort was not a pre-specified subgroup in the study protocol, but due to European labeling restrictions, results for all outcomes in this cohort are presented through 12 months.