Randomized Assessment of Ticagrelor Versus Prasugrel Antiplatelet Effects in Patients with ST-Segment–Elevation Myocardial Infarction

Ticagrelor versus prasugrel in patients with high on-clopidogrel treatment platelet reactivity after PCI: The ISAR-ADAPT-PF study

Patients with high on-treatment platelet reactivity (HTPR) on clopidogrel are at high risk for adverse cardiovascular events after percutaneous coronary intervention (PCI). The aim of the ISAR-ADAPT-PF study was to assess the antiplatelet efficacy of ticagrelor versus prasugrel in patients with HTPR on clopidogrel. In a prospective and randomized clinical study, 70 patients with HTPR on clopidogrel loading dose (LD) within 24 h post PCI were assigned to receive either ticagrelor [180 mg LD followed by 90 mg maintenance dose (MD) twice daily] or prasugrel (60 mg LD followed by 10 mg MD once daily). The adenosine diphosphate-induced platelet aggregation assessed on the Multiplate analyzer on day 2 after randomization (primary end point) was as follows: the mean difference between the two treatment groups was 6 aggregation units (AU) × min with an upper 95% confidence interval (CI) of 41 AU × min, which was greater than the predefined noninferiority margin of 18 AU × min (P for noninferiority = 0.29). However, no significant differences in absolute platelet reactivity levels between ticagrelor- versus prasugrel-treated patients at that time point were observed (138 ± 100 AU × min vs. 132 ± 64 AU × min, P for superiority = 0.77). In conclusion, neither drug was statistically more effective for inhibition of platelet aggregation in patients with HTPR on clopidogrel post PCI, although the study could not formally demonstrate the assumed noninferiority of ticagrelor versus prasugrel.

Pharmacodynamic Assessment of Platelet Reactivity After a Loading Dose of Prasugrel or Clopidogrel in Patients With ST-Segment Elevation Myocardial Infarction

BACKGROUND

Few studies have compared the platelet reactivity of prasugrel and clopidogrel in the acute phase of ST-segment elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Primary percutaneous coronary intervention (PCI) was performed in 78 patients with STEMI within 12 h of onset. Patients were randomly assigned to receive a Japanese standard loading dose of prasugrel 20 mg or clopidogrel 300 mg. Platelet reactivity was serially assessed using the VerifyNow-P2Y12 assay, the results of which were expressed as P2Y12-reaction-units (PRU). PRU values were significantly lower in the prasugrel group (n=38) than in the clopidogrel group (n=40) at 3 h, 24 h, and 14 days after loading (191±101 vs. 271±50, 147±80 vs. 261±57, and 171±67 vs. 221±70, respectively, P<0.05), although the PRU levels at baseline (231±57 vs. 237±58, P=0.65) and 1 h after loading (282±65 vs. 291±62, P=0.54) were similar. As compared with the baseline values, the PRU levels at 1, 3 and 24 h after clopidogrel loading were significantly higher (respectively, P<0.05), whereas only the PRU at 1 h after prasugrel was elevated (P<0.001).

CONCLUSIONS

In Japanese patients with STEMI who undergo primary PCI, prasugrel provides stronger platelet inhibition than clopidogrel from 3 h after loading, whereas platelet reactivity remained elevated within 24 h after clopidogrel loading. (Circ J 2016; 80: 2520-2527).

Cangrelor in combination with ticagrelor provides consistent and potent P2Y12-inhibition during and after primary percutaneous coronary intervention in real-world patients with ST-segment-elevation myocardial infarction

Patients pretreated with ticagrelor with less than 1 hour from percutaneous coronary intervention (PCI) or receiving ticagrelor in cath lab were prospectively included and received cangrelor. Cangrelor was infused for 2 hours and platelet function was assessed as P2Y12 reactivity units (PRU) with the VerifyNow P2Y12 function assay before start of infusion, 15 min after the start of infusion, and 30 min after the end of infusion. A total of n = 32 patients with an average age of 68 (±13) years with n = 22 (69%) males were included. The level of P2Y12 inhibition before cangrelor infusion was started was 249 PRU (IQR 221-271). After 15 min of cangrelor infusion the P2Y12 reactivity was markedly decreased to 71 PRU (IQR 52-104, p < 0.001). At 30 min after end of infusion PRU remained within the therapeutic range, 89 PRU (IQR 50-178; p < 0.001 for comparison with preinfusion) with only n = 4 (12.5%) patients with PRU >225. Results were consistent between patients receiving ticagrelor prehospital or in the cath lab and no statistical differences in PRU were noted between the two groups in any of the three measurements. In conclusion, cangrelor in combination with ticagrelor results in consistent and strong P2Y12 inhibition during and after infusion and cangrelor may bridge the gap until oral P2Y12 inhibitors achieve effect in real-world STEMI patients undergoing primary PCI.

Crushed Versus Integral Tablets of Ticagrelor in ST-Segment Elevation Myocardial Infarction Patients: A Randomized Pharmacokinetic/Pharmacodynamic Study

OBJECTIVE

The objective of this study was to assess the pharmacokinetic and pharmacodynamic behavior of ticagrelor administered either as crushed (in the semi-upright sitting position) or as integral (in the supine position) tablets in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI).

METHODS

We randomized 20 patients to ticagrelor 180 mg either as 2 integral tablets administered in the supine position (standard administration) or as 2 tablets crushed and dispersed, administered in the semi-upright sitting position. Blood samples were drawn for pharmacokinetic and pharmacodynamic assessment at randomization (0 h) and at 0.5, 1, 2, and 4 h.

RESULTS

At 1 h, ticagrelor plasma exposure and area under the plasma concentration-time curve from time zero to 1 h (AUC1) (co-primary endpoints) were higher in the crushed versus integral tablets group (median 586 vs. 70.1 ng/mL and 234 vs. 24.4 ng·h/mL, respectively), with a ratio of adjusted geometric means (95% confidence interval [CI]) of 12.67 (2.34-68.51) [p = 0.005] and 19.28 (3.51-106.06) [p = 0.002], respectively. Time to maximum plasma concentration was shorter in the crushed versus integral tablets group (median 2 vs. 4 h), with a ratio of adjusted geometric means (95% CI) of 0.69 (0.49-0.97) [p = 0.035]. Parallel findings were observed with AR-C124910XX (active metabolite). Platelet reactivity (VerifyNow(®)) at 1 h was lower with crushed versus standard administration with least squares estimates mean difference (95% CI) of 92 (-158.4 to 26.6) P2Y12 reaction units (p = 0.009).

CONCLUSIONS

In patients with STEMI undergoing primary PCI, ticagrelor crushed tablets administered in the semi-upright sitting position seems to lead to a faster-compared with standard administration-absorption, with stronger antiplatelet activity within the first hour.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02046486.

Efficacy of prasugrel administration immediately after percutaneous coronary intervention in ST-elevation myocardial infarction

Prasugrel, a potent thienopyridine, achieves stronger inhibition of platelet activation than clopidogrel. However, onset of inhibition is significantly delayed in patients with acute ST-elevation myocardial infarction (STEMI), as haemodynamic instability and morphine application seem to exhibit significant influence. Since rapid onset of effect was demonstrated in non-STEMI patients when prasugrel was administered only after percutaneous coronary intervention (PCI) without increasing cardiovascular event rates we assessed the efficacy of prasugrel loading immediately after PCI for STEMI instead of pre-loading before revascularisation. We investigated 50 consecutive patients with acute STEMI (mean age 56 ± 10 years) admitted for primary PCI. Prasugrel efficacy was assessed by platelet reactivity index (PRI; VASP assay) before, 1, 2, 4, 6, 12, and 24 hours following an oral loading dose of 60 mg immediately after PCI. High on-treatment platelet reactivity (HTPR) was defined as PRI>50 %. Prasugrel significantly and rapidly reduced platelet reactivity in acute STEMI patients (p<0.0001 at each time point vs control). Morphine application resulted in a significantly higher HTPR rate among patients having received morphine less than 1 hour before prasugrel loading (p<0.001) while concomitant metoclopramide (MCP) treatment did not significantly affect prasugrel efficacy. In conclusion, in contrast to previous reports describing a significant delay in onset of prasugrel-mediated P2Y₁₂ inhibition in acute STEMI, we observed a rapid onset with low HTPR rates comparable to those observed in stable non-STEMI patients. Prasugrel administered directly after primary PCI might therefore be a useful therapeutic strategy in patients with STEMI to provide strong and effective P2Y₁₂ inhibition.

Randomised trial to compare a protective effect of Clopidogrel Versus TIcagrelor on coronary Microvascular injury in ST-segment Elevation myocardial infarction (CV-TIME trial)

AIMS

Ticagrelor has shown greater, more rapid and more consistent platelet inhibition than clopidogrel. However, the superiority of ticagrelor for preventing ischaemic damage in STEMI patients has not been proven. The aim of this trial was to assess whether ticagrelor is superior to clopidogrel in preventing microvascular injury in ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

Patients with STEMI underwent prospective random assignment to receive a loading dose (LD) of clopidogrel 600 mg or ticagrelor 180 mg (1:1 ratio) before primary percutaneous coronary intervention (PCI). As the primary endpoint, the index of microcirculatory resistance (IMR) was measured immediately after primary PCI. The secondary endpoint was the infarct size estimated from the wall motion score index (WMSI). A total of 76 patients were enrolled (clopidogrel group=38, ticagrelor group=38). The IMR in the ticagrelor group was significantly lower than that in the clopidogrel group (22.2±18.0 vs. 34.4±18.8 U, p=0.005). Cardiac enzymes were less elevated in the ticagrelor group than in the clopidogrel group (CK peak; 2,651±1,710 vs. 3,139±2,698 ng/ml, p=0.06). Infarct size, estimated by WMSI, was not different between the ticagrelor and clopidogrel groups at baseline (1.55±0.30 vs. 1.61±0.29, p=0.41) or after three months (1.42±0.33 vs. 1.47±0.33, p=0.57).

CONCLUSIONS

In patients with STEMI treated by primary PCI, a 180 mg LD of ticagrelor might be more effective in reducing microvascular injury than a 600 mg LD of clopidogrel, as demonstrated by IMR immediately after primary PCI.

Which platelet function test best reflects the in vivo plasma concentrations of ticagrelor and its active metabolite? The HARMONIC study

Aim of this study was assessment of the relationship between concentrations of ticagrelor and its active metabolite (AR-C124910XX) and results of selected platelet function tests. In a single-centre, cohort study, patients with myocardial infarction underwent blood sampling following a 180 mg ticagrelor loading dose intake (predose, 1, 2, 3, 4, 6, 12, 24 hours postdose) to perform pharmacokinetic and pharmacodynamic assessments. Platelet reactivity was evaluated using the VASP-assay, the VerifyNow device and the Multiplate analyzer. Analysis of 36 patients revealed high negative correlations between ticagrelor concentrations and platelet reactivity evaluated with all three platelet function tests (the VASP-assay: RS=-0.722; p<0.0001; the VerifyNow device: RS=-0.715; p<0.0001; the Multiplate analyzer: RS=-0.722; p<0.0001), with no significant differences between correlation coefficients. Similar results were found for AR-C124910XX. Platelet reactivity values assessed with all three methods generally correlated well with each other; however, a significantly higher correlation (p<0.02) was demonstrated between the VerifyNow and Multiplate tests (RS=0.707; p<0.0001) than in other assay combinations (the VASP-assay and the VerifyNow device: RS=0.595; p<0.0001; the VASP-assay and the Multiplate analyzer: RS=0.588; p<0.0001). With respect to the recognition of high platelet reactivity, we found higher measurement concordance between the VerifyNow and Multiplate tests compared with other assay combinations, while for low platelet reactivity, only results of the VerifyNow and Multiplate assay were related to each other. Platelet reactivity measurements performed with the VASP, VerifyNow and Multiplate tests show comparably strong negative correlations with ticagrelor and AR-C124910XX concentrations.

Prasugrel Versus Ticagrelor in Patients With Acute Myocardial Infarction Treated With Primary Percutaneous Coronary Intervention: Multicenter Randomized PRAGUE-18 Study

BACKGROUND

No randomized head-to-head comparison of the efficacy and safety of ticagrelor and prasugrel has been published in the 7 years since the higher efficacy of these newer P2Y₁₂ inhibitors were first demonstrated relative to clopidogrel.

METHODS

This academic study was designed to compare the efficacy and safety of prasugrel and ticagrelor in acute myocardial infarction treated with primary or immediate percutaneous coronary intervention. A total of 1230 patients were randomly assigned across 14 sites to either prasugrel or ticagrelor, which was initiated before percutaneous coronary intervention. Nearly 4% were in cardiogenic shock, and 5.2% were on mechanical ventilation. The primary end point was defined as death, reinfarction, urgent target vessel revascularization, stroke, or serious bleeding requiring transfusion or prolonging hospitalization at 7 days (to reflect primarily the in-hospital phase). This analysis presents data from the first 30 days (key secondary end point). The total follow-up will be 1 year for all patients and will be completed in 2017.

RESULTS

The study was prematurely terminated for futility. The occurrence of the primary end point did not differ between groups receiving prasugrel and ticagrelor (4.0% and 4.1%, respectively; odds ratio, 0.98; 95% confidence interval, 0.55-1.73; P=0.939). No significant difference was found in any of the components of the primary end point. The occurrence of key secondary end point within 30 days, composed of cardiovascular death, nonfatal myocardial infarction, or stroke, did not show any significant difference between prasugrel and ticagrelor (2.7% and 2.5%, respectively; odds ratio, 1.06; 95% confidence interval, 0.53-2.15; P=0.864).

CONCLUSIONS

This head-to-head comparison of prasugrel and ticagrelor does not support the hypothesis that one is more effective or safer than the other in preventing ischemic and bleeding events in the acute phase of myocardial infarction treated with a primary percutaneous coronary intervention strategy. The observed rates of major outcomes were similar but with broad confidence intervals around the estimates. These interesting observations need to be confirmed in a larger trial.

CLINICAL TRIAL REGISTRATION

URL: http://www.ClinicalTrials.gov. Unique identifier: NCT02808767.

Platelet function testing as a biomarker for efficacy of antiplatelet drugs

Despite the overwhelming evidence in support of the efficacy of dual antiplatelet therapy with aspirin and clopidogrel, it is also obvious that not all patients benefit from these drugs to the same extent. This interindividual variability in platelet responses may underlie clinical differences in drug efficacy, with potential for optimization of antiplatelet therapy to prevent ischemic events without excessively increasing bleeding risk. This review presents the current evidence regarding platelet function testing for monitoring of antiplatelet therapy, with emphasis on the prognostic value of platelet function testing to predict ischemic and bleeding events. The potential of platelet function testing to provide personalized antiplatelet therapy is also discussed, with an outlook toward the future of platelet function testing in high-risk individuals.

Impact of oral P2Y12 inhibitors on residual thrombus burden and reperfusion indexes in patients with ST-segment elevation myocardial infarction

AIMS

We sought to assess the impact of different oral P2Y12 receptor inhibitors on residual thrombus and reperfusion indexes in ST-segment elevation myocardial infarction patients enrolled in the COCTAIL II trial, which included 128 primary percutaneous coronary interventions randomized to intracoronary vs. intralesion abciximab bolus with or without thrombectomy.

METHODS

Patients were divided into three groups: clopidogrel (n = 44), prasugrel (n = 45) and ticagrelor (n = 39). Residual intra-stent thrombus was quantified by optical coherence tomography using both the number of cross-sections with thrombus area more than 10% and thrombus volume. Reperfusion indexes included thrombolysis in myocardial infarction (TIMI) flow, corrected TIMI frame count, myocardial blush grade (MBG) and complete ST-segment resolution (≥70%).

RESULTS

In the prasugrel group, optical coherence tomography depicted a lower percentage of cross-sections with residual thrombus area more than 10% [4.0 (1.0-8.5)], as compared with clopidogrel [8.0 (1.0-15.0), P = 0.011] and ticagrelor [7.0 (3.0-13.5), P = 0.026].A higher thrombus volume was found in the clopidogrel group 4.0 mm(2.7-6.2) as compared with the prasugrel group [2.8 mm(1.8-4.4), P = 0.023], whereas the other between-group comparisons yield no significant differences. The frequency of MBG 3 was higher in the prasugrel group (73.3%) as compared with clopidogrel (45.5%) and ticagrelor [(56.4%), P = 0.027]. Final TIMI flow, TIMI frame count and ST resolution were not significantly different across the three groups (P = 0.423, 0.179 and 0.848, respectively). At multivariate analysis, pretreatment with prasugrel was independently associated with MBG 3 (odds ratio = 3.93; 95% confidence interval = 1.01-15.39).

CONCLUSION

Prasugrel loading dose was associated with a lower percentage of cross-sections with residual thrombus area more than 10% as compared with both clopidogrel and ticagrelor, although intrastent thrombus volume was not significantly different between prasugrel and ticagrelor.The frequency of MBG 3 was the only reperfusion index that was significantly more prevalent in prasugrel treated group as compared with clopidogrel and ticagrelor groups.

Impact of Escalating Loading Dose Regimens of Ticagrelor in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: Results of a Prospective Randomized Pharmacokinetic and Pharmacodynamic Investigation

OBJECTIVES

The goal of this study was to assess the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of escalating ticagrelor loading dose (LD) regimens in primary percutaneous coronary intervention (PPCI).

BACKGROUND

Patients with ST-segment elevation myocardial infarction undergoing PPCI frequently have suboptimal platelet inhibition in the early hours after ticagrelor LD. The use of high ticagrelor LD regimens has been hypothesized to optimize platelet inhibition in PPCI.

METHODS

This was a prospective, randomized study of escalating ticagrelor LD regimens (180 mg, 270 mg, or 360 mg) in PPCI (N = 52). PK/PD analyses were performed before and 30 min, 1, 2, 4, 8, and 24 h post-LD. PK assessments included exposure to ticagrelor and its metabolite (AR-C124910XX). PD assessments included P2Y12 reaction units (PRU) measured by VerifyNow P2Y12 and platelet reactivity index (PRI) measured by vasodilator-stimulated phosphoprotein (VASP).

RESULTS

Platelet reactivity was elevated during the first 2 h post-LD. There were no differences in PRU between groups during the study time course (p = 0.179). There were no significant differences in PRU levels across groups at all time points, except at 1 h (p = 0.017) where platelet reactivity was lowest with a 270-mg LD. No differences were found between the 180-mg and 360-mg groups (primary endpoint; p > 0.999). High on-treatment platelet reactivity rates were not different across groups, except at 1 hour (p = 0.038). Parallel PD findings were observed with VASP-PRI. PK analysis showed a delay in ticagrelor absorption and generation of AR-C124910XX, irrespective of dose. Although morphine was associated with a delay in ticagrelor PK/PD, it was not an independent predictor of high on-treatment platelet reactivity.

CONCLUSIONS

ST-segment elevation myocardial infarction patients undergoing PPCI frequently exhibit impaired response to ticagrelor in the early hours after drug administration, which cannot be overcome by increasing LD regimens. These PD findings are largely attributed to an impaired PK profile, indicating a delay in drug absorption compared with that reported in stable clinical settings. (High Ticagrelor Loading Dose in STEMI; NCT01898442).

Cangrelor for the management and prevention of arterial thrombosis

INTRODUCTION

Despite advances in antiplatelet therapy, the optimum antithrombotic regimen during percutaneous coronary intervention (PCI) remains to be determined. Cangrelor is an intravenous, reversibly-binding platelet P2Y12 receptor antagonist with ultra-rapid onset and offset of action that is approved in Europe and United States for use in patients undergoing PCI. This article describes the background for the development of cangrelor, the biology, pharmacology and clinical evidence supporting its use, and its likely position in the future.

AREAS COVERED

The role of the platelet P2Y12 receptor in platelet biology and the implications of this for atherothrombotic disease are described. Currently unmet needs in antithrombotic management during and after PCI are discussed followed by a description of the chemistry, pharmacokinetics and pharmacodynamics of cangrelor, including its interactions with oral thienopyridines. Subsequently, the clinical trial evidence supporting its adoption into clinical practice is reviewed, including the evidence indicating its superiority over a strategy based on clopidogrel treatment alone. Expert commentary: The current status and future potential of cangrelor is discussed, including a view of its place in current clinical practice.

Ticagrelor vs clopidogrel followed by ticagrelor re-loading in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: A randomized, pharmacodynamic comparison

Among patients allocated to ticagrelor in the primary percutaneous coronary intervention (PCI) cohort of Platelet Inhibition and Patient Outcomes (PLATO) trial, 40.7% had received pre-randomization 600 mg of clopidogrel. This scenario is frequently employed in real-world practice. In a prospective, three-center, single-blind, parallel design study, 74 P2Y12 inhibitor-naive patients undergoing primary PCI were randomized (Hour 0) to ticagrelor 180 mg loading dose (LD) vs clopidogrel 600 mg LD followed after 2 h by ticagrelor 180 mg re-LD. Platelet reactivity (VerifyNow, in PRU) was assessed at Hour 0, 2, 4, 6, and 24. The primary comparison was non-inferiority of ticagrelor to clopidogrel followed by ticagrelor re-LD regarding platelet reactivity at 24 h using a prespecified margin of <35 PRU for the upper bound of the one-sided 97.5% confidence interval (CI). Ticagrelor was proven non-inferior to clopidogrel followed by ticagrelor re-LD with a difference between arms of 13.5 PRU (28.8 upper 97.5% CI), p = 0.001. At Hour 2, platelet reactivity was lower in ticagrelor only vs clopidogrel followed by ticagrelor re-LD groups with least square estimate mean difference (95% CI) -105.7 (-140.6 to -70.8), p < 0.001, without significant difference thereafter. In conclusion, in patients undergoing primary PCI, a strategy of ticagrelor LD only was proven non-inferior to clopidogrel LD followed by ticagrelor re-LD, in terms of antiplatelet efficacy at 24 h post-randomization and provided an earlier onset of platelet inhibition.

Why we need intravenous antiplatelet agents

Oral ADP-receptor antagonists combined with aspirin are the standard for dual antiplatelet therapy (DAPT) during percutaneous coronary intervention (PCI). However, the oral route of administration of ADP-receptor antagonists leaves them vulnerable to unpredictable and often inadequate platelet inhibition at the time of PCI, while their prolonged effects often lead to the decision not to load them prior to PCI. Intravenous antiplatelet agents, including glycoprotein IIb/IIIa inhibitors (GPI) and cangrelor, a reversible P2Y12 inhibitor, address these shortcomings. In June 2015, the US FDA approved cangrelor for the prevention of thrombotic events associated with coronary stenting. This review examines the current state of peri-PCI DAPT and demonstrates that the selective use of GPIs and intravenous ADP-antagonist agents reduces the risk of periprocedural thrombosis.

Optimal P2Y12 Inhibitor in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Network Meta-Analysis

OBJECTIVES

The study sought to compare the clinical efficacy and safety of P2Y12 inhibitors in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous intervention (PPCI).

BACKGROUND

Limited data exist regarding the comparative efficacy and safety of P2Y12 inhibitors in STEMI patients undergoing PPCI.

METHODS

Clinical trials enrolling STEMI patients were identified and relevant data was extracted. Major adverse cardiovascular events (MACE) were defined as the composite of all cause mortality, MI, and target vessel revascularization. Network meta-analysis was performed using Bayesian methods.

RESULTS

A total of 37 studies with 88,402 STEMI patients and 5,077 MACE were analyzed. Outcomes at 1 month (22 studies and 60,783 patients) suggest that prasugrel was associated with: lower MACE than clopidogrel (standard dose odds ratio [OR]: 0.59, 95% confidence interval [CI]: 0.50 to 0.69; high-dose OR: 0.60, 95% CI: 0.51 to 0.71; upstream OR: 0.79, 95% CI: 0.66 to 0.94), and ticagrelor (standard dose OR: 0.69, 95% CI: 0.56 to 0.84; upstream OR: 0.72, 95% CI: 0.50 to 1.05); lower mortality and MI than clopidogrel and standard ticagrelor; lower stroke risk than standard clopidogrel and standard or upstream ticagrelor; and lower stent thrombosis than standard or upstream clopidogrel. At 1-year (10 studies, n = 40,333) prasugrel was associated with lower mortality and MACE than other P2Y12 inhibitors. MACE was particularly lower with prasugrel in studies where patients received bivalirudin, drug-eluting stents, and but not glycoprotein IIb/IIIa inhibitor.

CONCLUSIONS

In STEMI patients undergoing PPCI, prasugrel and ticagrelor are more efficacious than clopidogrel; in addition, prasugrel was superior to ticagrelor particularly in conjunction with bivalirudin and drug-eluting stents.

Immediate response to prasugrel loading in patients with ST-elevation myocardial infarction: Predictors and outcome

INTRODUCTION

Information regarding immediate response to novel P2Y12 inhibitors in ST-elevation myocardial infarction (STEMI) is scarce and has been associated with adequate reperfusion. Recent studies have shown that the onset of anti-platelet effects of novel P2Y12 inhibitors in patients with STEMI might be slower and more variable than in stable coronary syndrome. We aimed to assess the predictors and significance of immediate platelet response to prasugrel loading in STEMI.

METHODS

Platelet aggregation (PA) was prospectively evaluated in STEMI patients upon prasugrel loading and at primary percutaneous coronary intervention (PPCI). Early platelet responsiveness was defined as percent reduction of PA from baseline to PPCI, divided by the time lapse from loading to PPCI. High- and low-platelet responsiveness was defined as above and below the median value respectively.

RESULTS

Fifty consecutive STEMI patients (age 58±8, 90% male) underwent PPCI with a mean door-to-balloon time of 42±15min. Mean PA upon prasugrel loading and at PPCI was 76±9% and 63±19%, respectively. Older age and prior aspirin use were predictors of low platelet responsiveness to prasugrel [β=(-0.33), p=0.02 and β=(-0.28), p=0.04, respectively]. Fast compared with slow responders demonstrated more frequent early ST resolution (93% vs. 72%, p=0.02) and lower peak troponin levels (76±62μg/L vs. 48±28μg/L, p=0.05).

CONCLUSIONS

Immediate platelet responsiveness to prasugrel among STEMI patients is highly variable and inversely associated with older age and prior aspirin use. Fast compared with slow responders have improved reperfusion and infarct size markers.

Mortality in primary angioplasty patients starting antiplatelet therapy with prehospital prasugrel or clopidogrel: a 1-year follow-up from the European MULTIPRAC Registry

Aim

MULTIPRAC was designed to provide insights into the use and outcomes associated with prehospital initiation of antiplatelet therapy with either prasugrel or clopidogrel in the context of primary percutaneous coronary intervention. After a previous report on efficacy and safety outcomes during hospitalization, we report here the 1-year follow-up data, including cardiovascular (CV) mortality.

Methods and results

MULTIPRAC is a multinational, prospective registry of patients with ST-elevation myocardial infarction (STEMI) from 25 hospitals in nine countries, all of which had an established practice of prehospital start of dual antiplatelet therapy in place. The key outcome was CV death at 1 year. Among 2,036 patients followed-up through 1 year, 49 died (2.4%), 10 during the initial hospitalization and 39 within 1 year after hospital discharge. The primary analysis was based on the P2Y₁₂-inhibitor, used from prehospital loading dose through hospital discharge. Prasugrel (n=824) was more commonly used than clopidogrel (n=425). The observed 1-year rates for CV death were 0.5% with prasugrel and 2.6% with clopidogrel. After adjustment for differences in baseline characteristics, treatment with prasugrel was associated with a significantly lower risk of CV death than treatment with clopidogrel (odds ratio 0.248; 95% confidence interval 0.06–0.89).

Conclusion

In STEMI patients from routine practice undergoing primary angioplasty, who were able to start oral antiplatelet therapy prehospital, treatment with prasugrel as compared to clopidogrel was associated with a lower risk of CV death at 1-year follow-up.

Design and Rationale of the APELOT Trial: A Randomized, Open-Label, Multicenter, Phase IV Study to Evaluate the Antiplatelet Effect of Different Loading Dose of Ticagrelor in Patients With Non-ST Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Ticagrelor is a direct acting on the P2Y12 receptor blocker, which provides faster and greater platelet inhibition than clopidogrel. However, several studies suggested that in ST-segment elevation myocardial infarction patients undergoing percutaneous coronary intervention (PCI), ticagrelor exhibits initial delay in the onset of antiplatelet action. Unlike ST-segment elevation myocardial infarction, in non-ST-segment elevation acute coronary syndrome (NSTE-ACS), management pathways are highly variable, and some patients may require surgery. Effect of higher loading dose (LD) of ticagrelor in patients with NSTE-ACS in providing faster and stronger inhibition of platelet aggregation is unknown and needs to be explored further.The AntiPlatelet Effect of different Loading dOse of Ticagrelor trial is an interventional, randomized, open-label, multicenter, phase IV trial designed to evaluate whether a high LD (360 mg) of ticagrelor compared with the conventional LD (180 mg) will result in a higher inhibition of platelet aggregation without increasing bleeding events in NSTE-ACS participants undergoing PCI.A total of 250 NSTE-ACS participants will be randomized to receive a ticagrelor LD (360 or 180 mg), followed by a maintenance dose of 90 mg twice a day (bid) starting 12 hours after the LD. The primary endpoint is platelet reactivity index measured by vasodilator-stimulated phosphoprotein phosphorylation 2 hours after the LD, and the secondary endpoints include occurrence of periprocedural myocardial infarction and bleeding events.The AntiPlatelet Effect of different Loading dOse of Ticagrelor trial will provide important information on the risks and benefits of a high LD (360 mg) of ticagrelor in achieving a faster and stronger platelet inhibition compared with the conventional LD (180 mg) in NSTE-ACS patients undergoing PCI.

Impact of an integrated treatment algorithm based on platelet function testing and clinical risk assessment: results of the TRIAGE Patients Undergoing Percutaneous Coronary Interventions To Improve Clinical Outcomes Through Optimal Platelet Inhibition study

Assessment of platelet reactivity alone for thienopyridine selection with percutaneous coronary intervention (PCI) has not been associated with improved outcomes. In TRIAGE, a prospective multicenter observational pilot study we sought to evaluate the benefit of an integrated algorithm combining clinical risk and platelet function testing to select type of thienopyridine in patients undergoing PCI. Patients on chronic clopidogrel therapy underwent platelet function testing prior to PCI using the VerifyNow assay to determine high on treatment platelet reactivity (HTPR, ≥230 P2Y12 reactivity units or PRU). Based on both PRU and clinical (ischemic and bleeding) risks, patients were switched to prasugrel or continued on clopidogrel per the study algorithm. The primary endpoints were (i) 1-year major adverse cardiovascular events (MACE) composite of death, non-fatal myocardial infarction, or definite or probable stent thrombosis; and (ii) major bleeding, Bleeding Academic Research Consortium type 2, 3 or 5. Out of 318 clopidogrel treated patients with a mean age of 65.9 ± 9.8 years, HTPR was noted in 33.3 %. Ninety (28.0 %) patients overall were switched to prasugrel and 228 (72.0 %) continued clopidogrel. The prasugrel group had fewer smokers and more patients with heart failure. At 1-year MACE occurred in 4.4 % of majority HTPR patients on prasugrel versus 3.5 % of primarily non-HTPR patients on clopidogrel (p = 0.7). Major bleeding (5.6 vs 7.9 %, p = 0.47) was numerically higher with clopidogrel compared with prasugrel. Use of the study clinical risk algorithm for choice and intensity of thienopyridine prescription following PCI resulted in similar ischemic outcomes in HTPR patients receiving prasugrel and primarily non-HTPR patients on clopidogrel without an untoward increase in bleeding with prasugrel. However, the study was prematurely terminated and these findings are therefore hypothesis generating.

Morphine delays the onset of action of prasugrel in patients with prior history of ST-elevation myocardial infarction

Delays in the onset of action of prasugrel during primary percutaneous coronary intervention (PPCI) have been reported and could be related to the effects of morphine on gastric emptying and subsequent intestinal absorption. The study objective was to determine whether morphine delays the onset of action of prasugrel in patients with a prior history of ST-elevation myocardial infarction (STEMI) treated with PPCI. This was a crossover study of 11 aspirin-treated patients with prior history of STEMI treated with PPCI, for which prasugrel and morphine had been previously administered. Patients were randomised to receive either morphine (5 mg) or saline intravenously followed by 60 mg prasugrel. Blood samples were collected before randomised treatment and over 24 hours after prasugrel administration. The inhibitory effects of prasugrel on platelets were determined using the VerifyNow P2Y12 assay and light transmission aggregometry. Plasma levels of prasugrel and prasugrel active metabolite were measured. Platelet reactivity determined by VerifyNow PRU, VerifyNow % Inhibition and LTA was significantly higher at 30-120 minutes (min) when morphine had been co-administered compared to when saline had been co-administered. Morphine, compared to saline, significantly delayed adequate platelet inhibition after prasugrel administration (158 vs 68 min; p = 0.006). Patients with delayed onset of platelet inhibition also had evidence of delayed absorption of prasugrel. In conclusion, prior administration of intravenous morphine significantly delays the onset of action of prasugrel. Intravenous drugs may be necessary to reduce the risk of acute stent thrombosis in morphine-treated STEMI patients undergoing PPCI.

Reducing Microvascular Dysfunction in Revascularized Patients with ST-Elevation Myocardial Infarction by Off-Target Properties of Ticagrelor versus Prasugrel. Rationale and Design of the REDUCE-MVI Study

Microvascular injury is present in a large proportion of patients with ST-elevation myocardial infarction (STEMI) despite successful revascularization. Ticagrelor potentially mitigates this process by exerting additional adenosine-mediated effects. This study aims to determine whether ticagrelor is associated with a better microvascular function compared to prasugrel as maintenance therapy after STEMI. A total of 110 patients presenting with STEMI and additional intermediate stenosis in another coronary artery will be studied after successful percutaneous coronary intervention (PCI) of the infarct-related artery. Patients will be randomized to treatment with ticagrelor or prasugrel for 1 year. FFR-guided PCI of the non-infarct-related artery will be performed at 1 month. Microvascular function will be assessed by measurement of the index of microcirculatory resistance (IMR) in the infarct-related artery and non-infarct-related artery, immediately after primary PCI and after 1 month. The REDUCE-MVI study will establish whether ticagrelor as a maintenance therapy may improve microvascular function in patients after revascularized STEMI.

Effects of P2Y12 receptor antagonists beyond platelet inhibition--comparison of ticagrelor with thienopyridines

The effect and clinical benefit of P2Y12 receptor antagonists may not be limited to platelet inhibition and the prevention of arterial thrombus formation. Potential additional effects include reduction of the pro-inflammatory role of activated platelets and effects related to P2Y12 receptor inhibition on other cells apart from platelets. P2Y12 receptor antagonists, thienopyridines and ticagrelor, differ in their mode of action being prodrugs instead of direct acting and irreversibly instead of reversibly binding to P2Y12 . These key differences may provide different potential when it comes to additional effects. In addition to P2Y12 receptor blockade, ticagrelor is unique in having the only well-documented additional target of inhibition, the equilibrative nucleoside transporter 1. The current review will address the effects of P2Y12 receptor antagonists beyond platelets and the protection against arterial thrombosis. The discussion will include the potential for thienopyridines and ticagrelor to mediate anti-inflammatory effects, to conserve vascular function, to affect atherosclerosis, to provide cardioprotection and to induce dyspnea.

Crushed Prasugrel Tablets in Patients With STEMI Undergoing Primary Percutaneous Coronary Intervention: The CRUSH Study

BACKGROUND

Platelet inhibitory effects induced by oral P2Y12 receptor antagonists are delayed in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI), which may be attributed to impaired absorption affecting drug pharmacokinetics (PK) and pharmacodynamics (PD). Crushing tablets has been suggested to lead to more favorable PK/PD profiles. To date, no studies have investigated the PK/PD effects of crushing prasugrel.

OBJECTIVES

This study sought to determine whether crushing prasugrel is associated with more favorable drug bioavailability and platelet inhibitory effects compared with whole tablets in STEMI patients undergoing PPCI.

METHODS

Our prospective, randomized, open-label study assessed STEMI patients undergoing PPCI (n = 52) who were treated with a prasugrel 60-mg loading dose (LD) either as whole or crushed tablets. PK/PD analyses were performed at 7 time points. PD effects were measured as P2Y12 reaction units and platelet reactivity index, and PK by plasma levels of prasugrel's active metabolite.

RESULTS

Compared with whole tablets, crushed prasugrel led to reduced P2Y12 reaction units by 30 min post-LD, which persisted at 1, 2 (164 vs. 95; least square mean difference = 68; 95% confidence interval: 10 to 126; primary endpoint), and 4 h post-LD. Significant differences were no longer present at 6 h post-LD. Parallel findings were shown with platelet reactivity index. Accordingly, high on-treatment platelet reactivity rates were reduced with crushed prasugrel. PK analyses showed a >3-fold faster absorption with crushed compared with whole prasugrel.

CONCLUSIONS

In STEMI patients undergoing PPCI, crushed prasugrel leads to faster drug absorption, and consequently, more prompt and potent antiplatelet effects compared with whole tablet ingestion. (Pharmacological Effects of Crushing Prasugrel in STEMI Patients; NCT02212028).

Systematic review and meta-analysis of optimal P2Y12 blockade in dual antiplatelet therapy for patients with diabetes with acute coronary syndrome

Background

Patients with diabetes are at increased risk of acute coronary syndromes (ACS) and their mortality and morbidity outcomes are significantly worse following ACS events, independent of other comorbidities. This systematic review sought to establish the optimum management strategy with focus on P2Y₁₂ blockade in patients with diabetes with ACS.

Methods

MEDLINE (1946 to present) and EMBASE (1974 to present) databases, abstracts from major cardiology conferences and previously published systematic reviews were searched to June 2014. Relevant randomised control trials with clinical outcomes for P2Y₁₂ inhibitors in adult patients with diabetes with ACS were scrutinised independently by 2 authors with applicable data was extracted for primary composite end point of cardiovascular death, myocardial infarction (MI) and stroke; enabling calculation of relative risks with 95% CI with subsequent direct and indirect comparison.

Results

Four studies studied clopidogrel in patients with diabetes, with two (3122 patients) having primary outcome data showing superiority of clopidogrel against placebo with RR0.84 (95% CI 0.72–0.99). Irrespective of management strategy, the newer agents prasugrel (2 studies) and ticagrelor (1 study) had a lower primary event rate compared with clopidogrel; RR 0.80 (95% CI 0.66 to 0.97) and RR 0.89 (95% CI 0.77 to 1.02), respectively. When ticagrelor was indirectly compared with prasugrel, there was a trend to an improved primary outcome with prasugrel (RR 1.11 (95% CI 0.94 to 1.31)) particularly in those managed with percutaneous coronary intervention (PCI) (RR 1.23 (95% CI 0.95 to 1.59)). Prasugrel demonstrated a statistical superiority with prevention of further MI with RR 1.48 (95% CI 1.11 to 1.97). This was not at the expense of increased major thrombolysis in MI (TIMI) bleeding rates RR 0.94 (95% CI 0.59 to 1.51).

Conclusions

This meta-analysis shows the addition of a P2Y₁₂ inhibitor is superior to placebo, with a trend favouring the use of prasugrel in patients with diabetes with ACS, particularly those undergoing PCI.

Intravenous Clopidogrel (MDCO-157) Compared with Oral Clopidogrel: The Randomized Cross-Over AMPHORE Study

BACKGROUND

The extent of P2Y12 inhibition during coronary intervention is an important determinant of ischemic complications. The currently available oral P2Y12 inhibitors are limited by a relatively slow onset of action and variable on-treatment response.

OBJECTIVE

Our objective was to determine the pharmacodynamic (PD) dose-antiplatelet response relationship and the pharmacokinetics of MDCO-157, an intravenous formulation of clopidogrel complexed with sulphobutylether betacyclodextrin, and to identify the dose level of MDCO-157 that matches the PD effect of oral clopidogrel 300 mg.

METHODOLOGY

A randomized open-label crossover study was performed in 33 healthy adult volunteers to determine the pharmacokinetic (clopidogrel and clopidogrel H4 thiol active metabolite) and the PD (vasodilator-stimulated phosphoprotein [VASP]) effects of MDCO-157 at doses of 75, 150, and 300 mg and of oral clopidogrel 300 mg.

RESULTS

Data are presented as %, mean (standard deviation). The maximum effect of P2Y12 receptor inhibition assessed by flow cytometry using VASP was 70.42 (6.7), 69.45 (7.1), and 65.58 (12.6) for intravenous MDCO-157 at doses of 75, 150, and 300 mg, respectively, compared with 56.6 (17.5) with oral clopidogrel 300 mg administration (p < 0.0001). Intravenous administration of MDCO-157 led to a stepwise increase in plasma exposure of clopidogrel, higher than with administration of an oral dose of 300 mg (p < 0.0001). Plasma exposure of H4-thiol also increased with intravenous dose (3.6 ± 2.6, 6.9 ± 4.6, and 12.4 ± 9.1 h·ng/ml for intravenous 75, 150, and 300 mg, respectively) but was lower than with oral administration of a 300-mg dose (34.0 ± 16.0 h.ng/ml; pairwise p < 0.0001).

CONCLUSIONS

MDCO-157, an intravenous formulation of clopidogrel complexed with sulphobutylether betacyclodextrin, did not show significant platelet inhibition when administered at doses up to 300 mg. Higher doses with longer infusion may be needed to reach a sufficient threshold of active metabolite generation.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01860105.

Post-Procedural Bivalirudin Infusion Following Primary PCI to Reduce Stent Thrombosis

BACKGROUND

Prolonging infusions may abrogate the acute stent thrombosis (ST) associated with bivalirudin use during primary PCI but at an increased cost. We hypothesized that continuing the bivalirudin infusion commenced during the procedure at the PCI recommended dose until infusion end would prevent excess early ST.

METHODS

Baseline demographics, procedural data and outcomes were gathered prospectively on 1395 consecutive patients undergoing primary PCI. The choice of bivalirudin versus heparin was at the cardiologist's discretion. Local protocol recommended continuation of the procedural bivalirudin at the PCI dose until infusion end.

RESULTS

Patients' mean age was 62.8 ± 13.1years with 11.4% presenting with shock. The majority of patients underwent PCI using bivalirudin with fewer using heparin (87.7 vs. 12.3%, P < 0.0001). Glycoprotein inhibitor bailout rates were 6.1% with bivalirudin and 36.3% with heparin (P < 0.0001). Calculated on an individual patient basis the median intra-procedure duration of the bivalirudin infusion was 30(IQR 21-43) minutes and post-procedure 49(32-66) minutes. The acute (<24-hours) ST rates were 4/1224 with bivalirudin ± GPI (0.3%) and 0/171 with heparin ± GPI (0%, P = 0.41). The sub-acute (24-hours to 30-days) ST rates were 3/1224 for bivalirudin ± GPI (0.3%) and 2/171 with heparin ± GPI (1.2%, P = 0.11). In total the early (<30-days) ST rates were 7/1224 for bivalirudin ± GPI (0.6%) and 2/171 with heparin ± GPI (1.2%, P = 0.31). Acute ST was significantly more likely to occur in clopidogrel-loaded patients than prasugrel/ticagrelor patients (2.7 vs. 0.5%, P = 0.003).

CONCLUSION

Continuing the bivalirudin infusion commenced during the procedure at the PCI recommended dose until infusion end combined with potent P2 Y12 inhibitors ameliorates excess early stent thrombosis.

Prasugrel (Efient®) with percutaneous coronary intervention for treating acute coronary syndromes (review of TA182): systematic review and economic analysis

BACKGROUND

Acute coronary syndromes (ACSs) are life-threatening conditions associated with acute myocardial ischaemia. There are three main types of ACS: ST segment elevation myocardial infarction (STEMI), non-ST segment elevation myocardial infarction (NSTEMI) and unstable angina (UA). One treatment for ACS is percutaneous coronary intervention (PCI) plus adjunctive treatment with antiplatelet drugs. Dual therapy antiplatelet treatment [aspirin plus either prasugrel (Efient(®), Daiichi Sankyo Company Ltd UK/Eli Lilly and Company Ltd), clopidogrel or ticagrelor (Brilique(®), AstraZeneca)] is standard in UK clinical practice. Prasugrel is the focus of this review.

OBJECTIVES

The remit is to appraise the clinical effectiveness and cost-effectiveness of prasugrel within its licensed indication for the treatment of ACS with PCI and is a review of National Institute for Health and Care Excellence technology appraisal TA182.

DATA SOURCES

Four electronic databases (MEDLINE, EMBASE, The Cochrane Library, PubMed) were searched from database inception to June 2013 for randomised controlled trials (RCTs) and to August 2013 for economic evaluations comparing prasugrel with clopidogrel or ticagrelor in ACS patients undergoing PCI.

METHODS

Clinical outcomes included non-fatal and fatal cardiovascular (CV) events, adverse effects of treatment and health-related quality of life (HRQoL). Cost-effectiveness outcomes included incremental cost per life-year gained and incremental cost per quality-adjusted life-year (QALY) gained. An independent economic model assessed four mutually exclusive subgroups: ACS patients treated with PCI for STEMI and with and without diabetes mellitus and ACS patients treated with PCI for UA or NSTEMI and with and without diabetes mellitus.

RESULTS

No new RCTs were identified beyond that reported in TA182. TRITON-TIMI 38 (Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition with Prasugrel Thrombolysis in Myocardial Infarction 38) compared prasugrel with clopidogrel in ACS patients scheduled for PCI. No relevant economic evaluations were identified. Our analyses focused on a key subgroup of patients: those aged < 75 years who weighed > 60 kg (no previous stroke or transient ischaemic attack). For the primary composite end point (death from CV causes, non-fatal myocardial infarction or non-fatal stroke) statistically significantly fewer events occurred in the prasugrel arm (8.3%) than in the clopidogrel arm (11%). No statistically significant difference in major bleeding events was noted. However, there was a significant difference in favour of clopidogrel when major and minor bleeding events were combined (3.0 vs. 3.9%). No conclusions could be drawn regarding HRQoL. The results of sensitivity analyses confirmed that it is likely that, for all four ACS subgroups, within 5-10 years prasugrel is a cost-effective treatment option compared with clopidogrel at a willingness-to-pay threshold of £20,000 to £30,000 per QALY gained. At the full 40-year time horizon, all estimates are < £10,000 per QALY gained.

LIMITATIONS

Lack of data precluded a clinical comparison of prasugrel with ticagrelor; the comparative effectiveness of prasugrel compared with ticagrelor therefore remains unknown. The long-term modelling exercise is vulnerable to major assumptions about the continuation of early health outcome gains.

CONCLUSION

A key strength of the review is that it demonstrates the cost-effectiveness of prasugrel compared with clopidogrel using the generic price of clopidogrel. Although the report demonstrates the cost-effectiveness of prasugrel compared with clopidogrel at a threshold of £20,000 to £30,000 per QALY gained, the long-term modelling is vulnerable to major assumptions regarding long-term gains. Lack of data precluded a clinical comparison of prasugrel with ticagrelor; the comparative effectiveness of prasugrel compared with ticagrelor therefore remains unknown. Well-audited data are needed from a long-term UK clinical registry on defined ACS patient groups treated with PCI who receive prasugrel, ticagrelor and clopidogrel.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005047.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A Safety Evaluation of Cangrelor in Patients Undergoing PCI

INTRODUCTION

Dual antiplatelet therapy with aspirin and an oral ADP P2Y12 receptor antagonist is the standard-of-care for treatment of patients undergoing percutaneous coronary intervention (PCI). However, oral P2Y12 receptor antagonists have several limitations, including inter- and intra-individual response variability, drug-drug interactions, slow onset and offset of action and delayed platelet inhibition in high-risk clinical settings, such as patients with ST-segment elevation myocardial infarction.

AREAS COVERED

Cangrelor is an intravenous, direct-acting, reversible, potent P2Y12 receptor antagonist. It rapidly achieves near complete platelet inhibition and has a very short half-life and a fast offset of action. We conducted a systematic review searching PubMed/MEDLINE for pharmacodynamic/pharmacokinetic studies and clinical trials in which cangrelor was investigated, published from any time up to November 1(st) 2015. For clinical trials, those investigating cangrelor in the setting of PCI were considered for discussion.

EXPERT OPINION

Cangrelor is approved by drug regulating authorities worldwide as adjunctive antithrombotic therapy for the full spectrum of patients undergoing PCI, not pre-treated with a P2Y12 receptor inhibitor and not with intent to receive a glycoprotein IIb/IIIa inhibitor. Its unique pharmacological properties and its favorable safety and efficacy profile make it an attractive treatment strategy, especially in clinical settings where immediate platelet inhibition is required.

Upstream clopidogrel, prasugrel, or ticagrelor for patients treated with primary angioplasty: Results of an angiographic randomized pilot study

OBJETIVES

The main objective of the present randomized pilot study was to explore the effects of upstream prasugrel or ticagrelor or clopidogrel for patients with ST-segment-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

BACKGROUND

Administration of clopidogrel "as soon as possible" has been advocated for STEMI. Pretreatment with prasugrel and ticagrelor may improve reperfusion. Currently, the angiographic effects of upstream administration of these agents are poorly understood.

METHODS

A total of 132 patients with STEMI within the first 12 hr of chest pain referred to primary angioplasty were randomized to upstream clopidogrel (600 mg), prasugrel (60 mg), or ticagrelor (180 mg) while still in the emergency room. All patients underwent protocol-mandated thrombus aspiration.

RESULTS

Macroscopic thrombus material was retrieved in 79.5% of the clopidogrel group, 65.9% of the prasugrel group, and 54.3% of the ticagrelor group (P = 0.041). At baseline angiography, large thrombus burden was 97.7% vs. 87.8% vs. 80.4% in the clopidogrel, prasugrel, and ticagrelor groups, respectively (P = 0.036). Also, at baseline, 97.7% presented with an occluded target vessel in the clopidogrel group, 87.8% in the prasugrel group and 78.3% in the ticagrelor group (P = 0.019). At the end of the procedure, the percentages of patients with combined TIMI grade III flow and myocardial blush grade III were 52.3% for clopidogrel, 80.5% for prasugrel, and 67.4% for ticagrelor (P = 0.022).

CONCLUSIONS

In patients with STEMI undergoing primary PCI within 12 hr, upstream clopidogrel, prasugrel or ticagrelor have varying angiographic findings, with a trend toward better results for the latter two agents. © 2015 Wiley Periodicals, Inc.

Inter-patient variability of platelet reactivity in patients treated with prasugrel and ticagrelor

The aim of this study was to evaluate the distribution of platelet reactivity values in patients treated with prasugrel and ticagrelor. This prospective observational study enrolled 200 patients treated with prasugrel or ticagrelor. Platelet aggregation was determined by multiple electrode aggregometry after stimulation with adenosine diphosphate (ADP) in the maintenance phase of treatment with prasugrel or ticagrelor. Only 3% of patients in the prasugrel group and 2% of study participants in the ticagrelor group had high on treatment platelet reactivity (HTPR). The majority of patients displayed low on treatment platelet reactivity (LTPR; prasugrel: 69%; ticagrelor: 64%). The pharmacodynamic effect was similar in patients treated with prasugrel and ticagrelor: the median level of ADP-induced platelet aggregation was 15U (interquartile range IQR 9-21U) under prasugrel treatment and 17U (IQR 8-24U) under ticagrelor treatment (p=0.370). In conclusion, our study suggests that there is some degree of variability in ADP-induced platelet aggregation under treatment with prasugrel and ticagrelor.

Ticagrelor: Pharmacokinetic, Pharmacodynamic and Pharmacogenetic Profile: An Update

Despite advancements in treatments for acute coronary syndromes over the last 10 years, they continue to be life-threatening disorders. Currently, the standard of treatment includes dual antiplatelet therapy consisting of aspirin plus a P2Y12 receptor antagonist. The thienopyridine class of P2Y12 receptor antagonists, clopidogrel and prasugrel, have demonstrated efficacy. However, their use is associated with several limitations, including the need for metabolic activation and irreversible P2Y12 receptor binding causing prolonged recovery of platelet function. In addition, response to clopidogrel is variable and efficacy is reduced in patients with certain genotypes. Although prasugrel is a more consistent inhibitor of platelet aggregation than clopidogrel, it is associated with an increased risk of life-threatening and fatal bleeding. Ticagrelor is an oral antiplatelet agent of the cyclopentyltriazolopyrimidine class and also acts through the P2Y12 receptor. In contrast to clopidogrel and prasugrel, ticagrelor does not require metabolic activation and binds rapidly and reversibly to the P2Y12 receptor. In light of new data, this review provides an update on the pharmacokinetic, pharmacodynamic and pharmacogenetic profiles of ticagrelor in different study populations. Recent studies report that no dose adjustment for ticagrelor is required on the basis of age, gender, ethnicity, severe renal impairment or mild hepatic impairment. The non-P2Y12 actions of ticagrelor are reviewed, showing indirect positive effects on cellular adenosine concentration and biological activity, by inhibition of equilibrative nucleoside transporter-1 independently of the P2Y12 receptor. CYP2C19 and ABCB1 genotypes do not appear to influence ticagrelor pharmacodynamics. A summary of drug interactions is also presented.