Residual platelet reactivity, bleedings, and adherence to treatment in patients having coronary stent implantation treated with prasugrel

An optimal window of platelet reactivity by LTA assay for patients undergoing percutaneous coronary intervention

Objective

This study was aimed to determine how platelet reactivity (PR) on dual antiplatelet therapy predicts ischemic and bleeding events in patients underwent percutaneous coronary intervention (PCI).

Design

A total of 2768 patients who had received coronary stent implantation and had taken aspirin 100 mg in combination with clopidogrel 75 mg daily for > 5 days were consecutively screened and 1885 were enrolled. The recruited patients were followed-up for 12 months. The primary end-point was the net adverse clinical events (NACE) of cardiovascular death, nonfatal myocardial infarction (MI), target vessel revascularization (TVR), stent thrombosis (ST) and any bleeding.

Result

1709 patients completed the clinical follow-up. By using the receiver operating characteristic (ROC) curve analysis, the optimal cut-off values were found to be 37.5 and 25.5% respectively in predicting ischemic and bleeding events. Patients were classified into 2 groups according to PR: inside the window group (IW) [adenosine diphosphate (ADP) induced platelet aggregation (PL_ADP) 25.5–37.4%)] and outside the window group (OW) (PL_ADP < 25.5% or ≥ 37.5%). The incidence of NACE was 16.8 and 23.1% respectively in the IW and OW group. The hazard ratio of NACE in IW group was significantly lower [0.69 (95% CI, 0.54–0.89, P = 0.004)] than that in the OW group during 12-month follow-up.

Conclusion

An optimal therapeutic window of 25.5–37.4% for PL_ADP predicts the lowest risk of NACE, which could be referred for tailored antiplatelet treatment while using LTA assay.

Trial registration

Trial registration number: ClinicalTrials.govNCT01968499. Registered 18 October 2013 - Retrospectively registered.

No Differences in Gastrointestinal Bleeding Risk among Clopidogrel-, Ticagrelor-, or Prasugrel-Based Dual Antiplatelet Therapy

The risk for gastrointestinal bleeding from dual antiplatelet therapy (DAPT) with new antiplatelets (prasugrel/ticagrelor) compared to clopidogrel is unclear.

AIM

To determine the risk and type of major (gastrointestinal bleeding requiring hospitalization) and minor (anemia and iron deficiency) gastrointestinal events with different types of DAPT.

METHODS

Retrospective observational cohort study of patients who started DAPT after percutaneous coronary intervention. Follow-up was censored after 12 months of DAPT, when a major gastrointestinal event occurred, or when DAPT was discontinued.

RESULTS

Among 1,327 patients (54.03% were treated with clopidogrel-based DAPT, 38.13% with ticagrelor-based DAPT, and 7.84% with prasugrel-based DAPT), 29.5% had at least one gastrointestinal event. Patients taking clopidogrel-DAPT were older, with more comorbidities, and higher gastrointestinal risk compared to those taking other DAPT regimens. Adjusted hazard ratios (HRs) showed no between-group differences in the risk for major (clopidogrel vs. new antiplatelets: HR 0.996; 95% confidence interval 0.497-1.996) and minor (HR 0.920; 0.712-1.189) gastrointestinal events. Most patients received proton pump inhibitors while on DAPT (93.3%) and after withdrawal (83.2%).

CONCLUSION

Prasugrel- or ticagrelor-based DAPT was not associated with increased gastrointestinal bleeding risk when compared to clopidogrel-DAPT. New antiplatelets do not necessarily need to be restricted to patients with low gastrointestinal risk.

Platelet CD40 ligand and bleeding during P2Y12 inhibitor treatment in acute coronary syndrome

Antiplatelet therapy through inhibition of the adenosine diphosphate (ADP)/P2Y12 pathway is commonly used in the treatment of acute coronary syndrome (ACS). Although efficient in preventing platelet activation and thrombus formation, it increases the risk of bleeding complications. In patients with ACS receiving platelet aggregation inhibitors, that is, P2Y12 blockers (n = 923), we investigated the relationship between plasma and platelet-associated CD40L levels and bleeding events (n = 71). Treatment with P2Y12 inhibitors in patients with ACS did not affect plasma-soluble CD40L levels, but decreased platelet CD40L surface expression (pCD40L) and platelet-released CD40L (rCD40L) levels in response to stimulation as compared to healthy controls. In vitro inhibition of the ADP pathway in healthy control platelets reduced both pCD40L and rCD40L levels. In a multivariable analysis, the reduced pCD40L level observed in ACS patients was significantly associated with the risk of bleeding occurrence (adjusted odds ratio = 0.15; 95% confidence interval = 0.034-0.67). P2Y12 inhibitor-treated (ticagrelor) mice exhibited a 2.5-fold increase in tail bleeding duration compared with controls. A significant reduction in bleeding duration was observed on CD40L+/+ but not CD40L-/- platelet infusion. In addition, CD40L blockade in P2Y12 inhibitor-treated blood samples from a healthy human reduced thrombus growth over immobilized collagen under arterial flow. In conclusion, measurement of pCD40L may offer a novel approach to assessing bleeding risk in patients with ACS who are being treated with P2Y12 inhibitors.

Therapeutic Window of Clopidogrel and Ticagrelor in Patients With Critical Limb-Threatening Ischemia

BACKGROUND

Critical limb-threatening ischemia (CLTI) is associated with an increased risk of major adverse limb events and mortality. High on-treatment platelet reactivity (HPR) is associated with an increased risk of ischemic events, while low on-treatment platelet reactivity (LPR) is associated with an increased risk of bleeding. This study investigates the frequency with which patients with CLTI on clopidogrel or ticagrelor achieve a "therapeutic window" (TW) of platelet inhibition.

METHODS

Data from the "Switch To Ticagrelor in Critical Limb Ischemia Anti-Platelet Study" were assessed retrospectively to determine the incidence of TW of on-treatment platelet reactivity in 50 consecutive patients with CLTI (mean age: 65.2 ± 10.5 years, 54% male). The data included 4 measurements of patients' platelet reactivity using the VerifyNow P2Y12 Assay: baseline and steady state platelet reactivity on clopidogrel 75 mg daily and on ticagrelor 90 mg twice daily.

RESULTS

At baseline, 46% of patients on clopidogrel were within TW of on-treatment platelet reactivity compared to 10% of patients on ticagrelor (P < .0001). At steady state, 42% of patients on clopidogrel were within the TW compared to 10% of patients on ticagrelor (P < .0001). Patients on ticagrelor exhibited higher rates of LPR compared to those on clopidogrel at baseline as well as at steady state (baseline 88% vs 18%, steady state 88% vs 28%; P < .0001).

CONCLUSION

Although ticagrelor has been proposed as an alternative for patients with HPR on clopidogrel, the current study observes an excess of platelet inhibition with ticagrelor in most patients with CLTI at a dose of 90 mg twice daily.

Comparison of lower loading dose of prasugrel with conventional loading dose of prasugrel in Indian patients undergoing percutaneous coronary interventions

Background

Although conventional 60 mg of prasugrel allows for rapid and potent platelet inhibition within 30 min after loading dose, the efficacy and safety of lower doses of prasugrel in Indian patients has not yet been investigated.

Objective

The study sought to compare the efficacy of a lower loading dose of prasugrel with conventional loading dose of prasugrel in Indian patients.

Material and methods

Three hundred thirty-two Indian patients undergoing elective percutaneous coronary intervention (PCI) were enrolled in the study. Participants were randomly administered loading doses of prasugrel 60 mg (group A, n = 166) or 30 mg (group B, n = 166) before undergoing elective PCI in a 1:1 manner. Primary efficacy end point was composite of in-hospital death and stent thrombosis at 96 h, while safety end point was in-hospital bleeding.

Results

The two groups did not differ in their baseline characteristics. The primary efficacy end point was 0.6% in both the conventional 60 mg loading dose (LD) and lower 30 mg LD groups (p = not significant). Minor bleeding was significantly less in group B [Bleeding Academic Research Consortium 1, A = 6.63% vs B = 1.81%, odds ratio (OR) = 3.86, 95% confidence interval (CI) = 1.06–14.08, P = 0.05]. Major bleeding was higher in group A (A = 3.61%, vs B = 1.81%, OR = 2.04, 95% CI = 0.50–8.29, P = 0.50).

Conclusion

In Indian patients, 30 mg of prasugrel loading is as effective as 60 mg of prasugrel with significantly less minor bleeding.

Systematic review with meta-analysis: the risk of gastrointestinal bleeding in patients taking third-generation P2Y12 inhibitors compared with clopidogrel

BACKGROUND

Ticagrelor and prasugrel are third-generation oral P2Y₁₂ receptor antagonists with rapid onset and pronounced platelet inhibition. However, higher overall bleeding rates have been reported for these agents when compared with clopidogrel.

AIM

To compare the risk of gastrointestinal bleeding (GIB) among users of third-generation P2Y₁₂ inhibitors with clopidogrel.

METHODS

We systematically searched for published randomised controlled trials of ticagrelor or prasugrel versus clopidogrel until September 2018. The primary outcome was the risk of GIB among users of third-generation P2Y₁₂ inhibitors when compared to clopidogrel, expressed as risk ratio (RR) and 95% confidence interval (CI). The rates of non-coronary artery bypass graft (CABG) major bleeding, life-threatening bleeding, fatal bleeding, and intracranial bleeding were analysed as secondary outcomes.

RESULTS

Forty-one studies were included in the analysis of non-CABG major bleeding, of which 12 were included in the analysis of GIB including 58 678 patients. Third-generation P2Y₁₂ inhibitors were associated with higher risk of GIB as compared with clopidogrel (RR 1.28, 95% CI 1.13-1.46). The findings were consistent for upper (RR 1.32, 95% CI 1.05-1.67) and unspecified GIB (RR 1.25, 95% CI 1.01-1.53), but not lower GIB (RR 1.25, 95% CI 0.95-1.65). Subgroup analysis showed higher GIB risk in prasugrel studies (RR 1.40, 95% CI 1.10-1.77) than in ticagrelor studies (RR 1.15, 95% CI 0.94-1.39). Third-generation P2Y₁₂ inhibitors also increased the risk of non-CABG major bleeding (RR 1.18, 95% CI 1.08-1.28).

CONCLUSION

Third-generation P2Y₁₂ inhibitors were associated with increased risk of GIB and non-CABG major bleeding when compared with clopidogrel.

Current Role of Platelet Function Testing in Percutaneous Coronary Intervention and Coronary Artery Bypass Grafting

There is interindividual variability in the pharmacodynamic response to antiplatelet medications. High on-treatment platelet reactivity, reflecting a failure to achieve adequate platelet inhibition, is associated with a higher risk for thrombotic events. Low on-treatment platelet reactivity, or an enhanced response to antiplatelet medications, has been linked to a higher risk for bleeding. There is evidence for the prognostic value of platelet function testing for risk prediction. This review presents the current evidence regarding platelet function testing in patients undergoing percutaneous cardiac intervention and coronary artery bypass grafting. The possible role of platelet function testing for individualized antiplatelet treatment is highlighted.

Management of antiplatelet therapy in patients undergoing neuroendovascular procedures

Neuroendovascular techniques for treating cerebral aneurysms and other cerebrovascular pathology are increasingly becoming the standard of care. Intraluminal stents, aneurysm coils, and other flow diversion devices typically require concomitant antiplatelet therapy to reduce thromboembolic complications. The variability inherent with the pharmacodynamic response to common antiplatelet agents such as aspirin and clopidogrel complicates optimal selection of antiplatelet agents by clinicians. This review serves to discuss the literature related to antiplatelet use in neuroendovascular procedures and provides recommendations for clinicians on how to approach patients with variable response to antiplatelet agents, particularly clopidogrel.

Antiplatelet Therapy Bridging With Cangrelor in Patients With Coronary Stents: A Case Series

BACKGROUND

Cangrelor is an intravenous P2Y₁₂ receptor antagonist approved for use during percutaneous coronary intervention (PCI) to reduce ischemic events associated with new stent placement and has been used off-label at reduced doses guided by platelet function testing as a "bridge" from discontinuation of oral P2Y₁₂ receptor antagonists to surgical procedures when the long-term effects of oral agents are undesirable.

OBJECTIVE

To describe the dosing, laboratory monitoring, and clinical outcomes of a series of patients who received cangrelor as a "bridging" antiplatelet agent.

METHODS

This study is a retrospective analysis of all patients within the study center with coronary stents who received cangrelor as a bridge to surgical procedure and had VerifyNow monitoring during treatment.

RESULTS

A total of 11 patients were identified for inclusion. The median cangrelor dose was 0.5 µg/kg/min (interquartile range = 0.5-0.5) and was maintained in 7 of 11 patients. Doses ranged from 0.25 to 2 µg/kg/min during therapy, and 81.6% of VerifyNow results assessed were within goal range (⩽208 P2Y₁₂ reaction units). Bleeding complications during therapy occurred in 3 patients, all of whom were receiving concomitant heparin infusions, and no stent thrombosis was reported. Conclusion and Relevance: Low-dose cangrelor may represent an effective option for bridging antiplatelet therapy in patients with coronary stents. This study demonstrated that the majority of patients received adequate platelet inhibition without any incidence of stent thrombosis on 0.5 µg/kg/min using the VerifyNow assay to monitor platelet inhibition, which represents a lower dose than previously reported in the literature.

On-Treatment Platelet Reactivity is a Predictor of Adverse Events in Peripheral Artery Disease Patients Undergoing Percutaneous Angioplasty

OBJECTIVES

Few data are available on the association between a different entity of platelet inhibition on antiplatelet treatment and clinical outcomes in patients with peripheral artery disease (PAD). The aim of this study was to evaluate the degree of on-treatment platelet reactivity, and its association with ischaemic and haemorrhagic adverse events at follow up in PAD patients undergoing percutaneous transluminal angioplasty (PTA).

METHODS

In this observational, prospective, single centre study, 177 consecutive patients with PAD undergoing PTA were enrolled, and treated with dual antiplatelet therapy with aspirin and a P2Y12 inhibitor. Platelet function was assessed on blood samples obtained within 24 h from PTA by light transmission aggregometry (LTA) using arachidonic acid (AA) and adenosine diphosphate (ADP) as agonists of platelet aggregation. High on-treatment platelet reactivity (HPR) was defined by LTA ≥ 20% if induced by AA, and LTA ≥ 70% if induced by ADP. Follow up was performed to record outcomes (death, major amputation, target vessel re-intervention, acute myocardial infarction and/or myocardial revascularisation, stroke/TIA, and bleeding).

RESULTS

HPR by AA and HPR by ADP were found in 45% and 32% of patients, respectively. During follow up (median duration 23 months) 23 deaths (13%) were recorded; 27 patients (17.5%) underwent target limb revascularisation (TLR), two (1.3%) amputation, and six (3.9%) myocardial revascularisation. Twenty-four patients (15.6%) experienced minor bleeding. On multivariable analysis, HPR by AA and HPR by ADP were independent predictors of death [HR 3.8 (1.2-11.7), p = .023 and HR 4.8 (1.6-14.5), p = .006, respectively]. The median value of LTA by ADP was significantly lower in patients with bleeding complications than in those without [26.5% (22-39.2) vs. 62% (44.5-74), p < .001). LTA by ADP ≤ 41% was independently associated with bleeding HR 14.6 (2.6-24.0), p = .001] on multivariable analysis.

CONCLUSIONS

In this study a high prevalence of on-clopidogrel and aspirin high platelet reactivity was found, which was significantly associated with the risk of death. Conversely, a low on-clopidogrel platelet reactivity was associated with a higher risk of bleeding. These results document that the entity of platelet inhibition is associated with both thrombotic and bleeding complications in PAD patients.

Antiplatelet Therapy in ACS Patients: Comparing Appropriate P2Y12 Inhibition by Clopidogrel to the Use of New P2Y12 Inhibitors

AIM

In percutaneous coronary intervention (PCI)-treated acute coronary syndrome (ACS) patients on clopidogrel therapy, high on-treatment platelet adenosine diphosphate (ADP) reactivity was observed in numerous studies, with significant increases in non-fatal myocardial infarction, definite/probable stent thrombosis, or cardiovascular mortality. Compared to clopidogrel, prasugrel and ticagrelor provide more potent platelet inhibition. Whether new P2Y12 inhibitors reduce thrombotic events in a similar manner compared to the rate observed with appropriate P2Y12 inhibition by clopidogrel must still be determined. This study sought to compare long-term outcomes between clopidogrel responders (platelet reactivity index [PRI] vasodilator-stimulated phosphoprotein [VASP] ＜61%) and patients under prasugrel or ticagrelor therapy following PCI-treated ACS.

METHODS

730 ACS patients undergoing urgent PCI were prospectively enrolled into two groups: clopidogrel responders (n=448) and those under ticagrelor or prasugrel therapy (n=282). The primary endpoint was a composite of cardiovascular death, myocardial infarction, stent thrombosis, and stroke; the secondary endpoint comprised major hemorrhagic events.

RESULTS

The median follow-up was 260±186 days. Clopidogrel patients were older and more likely to present non-ST segment elevation myocardial infarction, cardiovascular risk factors, atrial fibrillation, or prior vascular disease. After propensity score matching, the primary endpoint was met in 7.1% of the clopidogrel group and 4.1% of the prasugrel/ticagrelor group (p=0.43). Minor bleeding events were significantly reduced in the clopidogrel group (1.1% vs. 3%; p=0.03). In a multivariate analysis, the antiplatelet treatment strategy was not an independent primary endpoint predictor.

CONCLUSION

In PCI-treated ACS patients, clopidogrel therapy and PRI VASP ＜61% were not associated with increased risks of thrombotic events compared to prasugrel or ticagrelor therapy.

How to improve the concept of individualised antiplatelet therapy with P2Y12 receptor inhibitors – is an algorithm the answer?

Within the past decade, high on-treatment platelet reactivity (HTPR) on clopidogrel and its clinical implications have been frequently discussed. Although it has been previously assumed that HTPR is a phenomenon occurring only in patients treated with clopidogrel, recent data show that HTPR might also occur during treatment with prasugrel or ticagrelor in the acute phase of ST-elevation myocardial infarction. Moreover, it has been postulated that there is a therapeutic window for P2Y12 receptor blockers, thus indicating that HTPR is associated with thrombotic events whereas low on-treatment platelet reactivity (LTPR) is associated with bleeding events. The current paper focuses on tools to identify risk factors for HTPR (pharmacogenomic testing, clinical scoring and drug-drug interactions) and on the use of platelet function testing in order to identify patients who might not respond adequately to clopidogrel. The majority of recent clinical randomised trials have not supported the hypothesis that platelet function testing and tailored antiplatelet therapy are providing a favourable clinical outcome. These trials, mainly performed in low-to-moderate risk patients, will be reviewed and discussed. Finally, an algorithm based on current knowledge is suggested, which might be of use for design of clinical trials.

Assessment of bleeding risk in patients with coronary artery disease on dual antiplatelet therapy

Patients with coronary artery disease are usually treated with dual antiplatelet therapy (DAPT) after percutaneous coronary intervention. Patients on DAPT are at risk of both ischaemic and bleeding events. Although side-lined for a long time, real-life studies have shown that both the incidence and the associated morbidity and mortality of outof-hospital bleeding are high. This indicates that prevention of (postinterventional) bleeding is as important as prevention of ischaemia. For this purpose it is crucial to reliably identify patients with a high bleeding risk. In order to postulate an algorithm, which could help identifying these patients, we performed a systematic review to determine the value of previously proposed prognostic modalities for bleeding. We searched and appraised the following tools: platelet function tests, genetic tests, bleeding scores and questionnaires and haemostatic tests. Most studies indicated that low on-treatment platelet reactivity (LTPR), as measured by several platelet function tests, and the carriage of CYP2C19*17 allele were independent risk factors for bleeding. A bleeding score also proved to be helpful in identifying patients at risk. No studies on haemostatic tests were retrieved. Several patient characteristics were also identified as independent predictors of bleeding, such as older age, female sex and renal failure. Combining these risk factors we propose an algorithm that would hypothetically facilitate identification of those patients at highest risk, warranting prevention measures for bleeding. This could be a starting point for further research concerning the topic.

Platelet Aggregometry Testing: Molecular Mechanisms, Techniques and Clinical Implications

Platelets play a fundamental role in normal hemostasis, while their inherited or acquired dysfunctions are involved in a variety of bleeding disorders or thrombotic events. Several laboratory methodologies or point-of-care testing methods are currently available for clinical and experimental settings. These methods describe different aspects of platelet function based on platelet aggregation, platelet adhesion, the viscoelastic properties during clot formation, the evaluation of thromboxane metabolism or certain flow cytometry techniques. Platelet aggregometry is applied in different clinical settings as monitoring response to antiplatelet therapies, the assessment of perioperative bleeding risk, the diagnosis of inherited bleeding disorders or in transfusion medicine. The rationale for platelet function-driven antiplatelet therapy was based on the result of several studies on patients undergoing percutaneous coronary intervention (PCI), where an association between high platelet reactivity despite P2Y12 inhibition and ischemic events as stent thrombosis or cardiovascular death was found. However, recent large scale randomized, controlled trials have consistently failed to demonstrate a benefit of personalised antiplatelet therapy based on platelet function testing.

Prasugrel hydrochloride for the treatment of acute coronary syndrome patients

INTRODUCTION

Dual antiplatelet therapy (DAPT) with aspirin combined with either a thienopyridine (clopidogrel or prasugrel) or acyclopentyl-triazolo-pyrimidine (ticagrelor) plays a vital role in the management of acute coronary syndrome (ACS) especially in those undergoing percutaneous coronary intervention (PCI) but even those being managed medically. Observational studies and some formal studies have shown patients on the standard dual antiplatelet regimen (clopidogrel and aspirin) continue to have further ischemic events and can suffer stent thrombosis. It has been demonstrated that clopidogrel is associated with a delayed onset of action with a considerable inter-individual variation to treatment thus making it difficult to achieve an optimal level of platelet inhibition. Areas covered: This article will review the current evidence that is available regarding the effectiveness and safety of prasugrel in ACS patients undergoing percutaneous coronary intervention (PCI). Expert commentary: Prasugrel is an oral third-generation inhibitor of platelet activation and aggregation. Laboratory studies and early phase clinical trials show prasugrel has a faster onset of action, is more potent and has reduced inter-patient response variability compared to clopidogrel. The published studies so far demonstrated that prasugrel when compared to clopidogrel also shows a higher degree of effectiveness in the prevention of platelet-initiated thrombotic events in patients with ACS undergoing PCI, however these benefits are offset somewhat by an increased bleeding risk.

Parathyroid Hormone Levels and High-Residual Platelet Reactivity in Patients Receiving Dual Antiplatelet Therapy With Acetylsalicylic Acid and Clopidogrel or Ticagrelor

BACKGROUND

High-residual-on-treatment platelet reactivity still represents a challenging issue, potentially vanishing the benefits of dual antiplatelet treatment in patients with coronary artery disease. However, very few is known on the determinants of suboptimal response to antiplatelet agents. Recent interests have emerged on the potential prothrombotic effect of parathyroid hormone (PTH). Therefore, the aim of the present study was to assess the impact of parathyroid hormone (PTH) on platelet reactivity in patients receiving DAPT after an acute coronary syndrome or PCI.

METHODS

Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30- to 90-days postdischarge. By whole blood impedance aggregometry, HRPR was considered for ASPI test >862 AU*min (for ASA) and ADP test values ≥417 AU*min (for ADP antagonists).

RESULTS

We included 362 patients on DAPT, 125 (34.5%) receiving clopidogrel, and 237 (65.5%) on ticagrelor. Patients were divided according to PTH quartiles values (<45.8; 45.8-60.3; 60.4-88; ≥88.1 pg/mL). Higher PTH was associated with older age (P = 0.001); renal failure (P < 0.001), higher HDL cholesterol (P = 0.006) and creatinine (P < 0.001) and lower 25-OH cholecalciferol (P < 0.001). Suboptimal response to ASA was infrequent (2.8%), and not influenced by the levels of PTH (P = 0.57). ADP-mediated platelet aggregation was significantly increased in patients with higher PTH (P = 0.03), with an absolute increase in the prevalence of HRPR to ADP antagonists for higher PTH (24.7% vs. 40%, P = 0.007 for 4th vs. 1-3rd quartiles, adjusted OR[95%CI] = 2.04[1.14-3.64], P = 0.02). By the use of the ROC curve, we identified PTH levels above 96.7 pg/mL as the best predictor of HRPR with ADP antagonists (adjusted OR[95%CI] = 2.52[1.31-4.87], P = 0.006). Higher rate of HRPR was confirmed for PTH >96.7 pg/mL among the subgroup of patients on clopidogrel (51.5 vs. 85.7%, P = 0.001; adjusted OR[95%CI] = 12.5[2.6-60.9], P = 0.002), but not among ticagrelor-treated patients (11.3 vs. 16.7%, P = 0.31; adjusted OR[95%CI] = 1.55[0.56-4.6], P = 0.42).

CONCLUSION

In patients receiving dual antiplatelet therapy for coronary artery disease, higher PTH levels are associated with an increased ADP-mediated platelet reactivity and suboptimal response to clopidogrel, especially for values above 96.7 pg/mL, while not influencing the effectiveness of ASA and ticagrelor.

Bleeding events and maintenance dose of prasugrel: BLESS pilot study

Objective

To evaluate changes in residual platelet reactivity (RPR) over time, and bleeding and ischaemic events rate using 5 vs 10 mg maintenance dose (MD) regimens of prasugrel 1 month after acute coronary syndrome (ACS).

Background

The optimal level of RPR with prasugrel may change over time after an ACS.

Methods

After 60 mg loading dose of prasugrel (T0) followed by 10 mg/day for 1 month, patients were randomised to receive prasugrel 10 mg/day (n=95, group A) or 5 mg/day MD (n=98, group B) up to 1 year. RPR was assessed at T0, 37 (T1) and 180 days (T2). The primary end point was Bleeding Academic Research Consortium (BARC) bleeding events ≥2 between 1 and 12 months, and the secondary composite end point was cardiac death, myocardial infarction, stroke and definite/probable stent thrombosis.

Results

From T0 to T1, RPR significantly increased in both groups A and B and the increase was higher for group B (δ ADP 10 µmol: 13.8%±14.7% vs 23.5%±19.2%, p=0.001). At T2 a lower rate of high RPR patients were found in group A (2.6% vs13.3%; p=0.014). The BARC type ≥2 bleeding occurred in 12.6% of group A versus 4.1% of group B (OR 0.29, 95% CI 0.09 to 0.94) and secondary end point in 2.1% vs 1.0% (p=0.542), respectively, without stent thrombosis.

Conclusions

RPR increases shifting from 60 mg loading dose to 10 mg/day prasugrel MD with a further increase of RPR reducing prasugrel MD to 5 mg 1 month after ACS. Clinical value of these pharmacodynamic findings should be proved in larger clinical trials.

Trial registration number

NCT01790854.

Adherence to antiplatelet treatment with P2Y12 receptor inhibitors. Is there anything we can do to improve it? A systematic review of randomized trials

Antiplatelet therapy is the cornerstone of treatment for patients with acute coronary syndromes (ACS) and/or undergoing percutaneous coronary interventions. Non-adherence to medication after ACS may lead to increased morbidity, mortality, and costs to the healthcare system due to elevated risk of stent thrombosis, myocardial infarction or death. Medication adherence is an issue of growing concern regarding the improvement of health system performance. Promoting medication adherence offers a rare opportunity to simultaneously improve health outcomes while reducing costs of treatment in patients with coronary artery disease (CAD). The aim of this systematic review was to critically discuss adherence to antiplatelet treatment with P2Y12 receptor inhibitors in CAD patients. After a systematic investigation of the literature in databases including PubMed, CENTRAL and Google Scholar, using appropriate keywords, and considering clinical randomized, prospective observational and retrospective studies, reporting on adherence to treatment with inhibitors of P2Y12 platelet receptors or educational interventions aimed to improve medication adherence in patients with CAD, seven articles were considered eligible for inclusion in this systematic review. Reported adherence to clopidogrel, despite catastrophic consequences of its premature discontinuation, is low. We identified several determinants of low adherence and early discontinuation of clopidogrel. We also present data on the usefulness, utilization and credibility of different methods of medication adherence assessment, and suggest and critically discuss available interventions aimed at improvement of adherence to clopidogrel, still showing the need for innovative approaches to achieve enhanced medication adherence and improve health outcomes after acute myocardial infarction.

One-year incidence and clinical impact of bleeding events in patients treated with prasugrel or clopidogrel after ST-segment elevation myocardial infarction

BACKGROUND

Little information is available on the long-term incidence of bleeding events after ST-segment elevation myocardial infarction (STEMI) with the current antithrombotic strategy.

AIMS

To evaluate the effect of bleedings for up to 12months on clinical events and therapeutic compliance in unselected STEMI patients treated with prasugrel or clopidogrel.

METHODS

Patients were treated with clopidogrel or prasugrel according to guidelines. The primary endpoint was first occurrence of a bleeding event from hospital discharge to 12months, assessed by the Bleeding Academic Research Consortium (BARC) classification using a dedicated questionnaire. Topography of bleedings, causes of premature cessation and ischaemic events were compared between clopidogrel- and prasugrel-treated patients.

RESULTS

A total of 390 patients were enrolled (211 in the prasugrel group, 179 in the clopidogrel group). Elderly, female and low-body weight patients were more likely to receive clopidogrel. At 12months, the incidence of major bleedings (BARC 3) was lower with prasugrel (1% vs 6%; P=0.02), mainly due to fewer transfusions. Elderly age was a risk factor for severe bleeding. Premature treatment cessation was related to ischaemic complications (P=0.03), and occurred more frequently with prasugrel (P=0.001). One-year mortality was very low (1.9 per 100 person-years, 95% confidence interval 0.9-4.0), and was higher in the clopidogrel group (P=0.03).

CONCLUSIONS

In this unselected STEMI population, the rate of major bleedings with prasugrel at 12months was low, but nuisance bleedings were frequent and led to more premature cessations than with clopidogrel. Prevention of bleeding complications, even minor, is necessary to prevent disruption of antithrombotic medication.

Adherence to antiplatelet therapy after percutaneous coronary intervention: a population study in a region of Italy

AIMS

We evaluated adherence to dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) for patients in the Lazio region of Italy and the impact of discharge ward type on therapy discontinuation.

METHODS

From the Hospital Information System, we selected patients who underwent PCI from 2006 to 2007 and obtained Regional Drug Dispense Registry data for antiplatelet drugs prescribed for 12 months after discharge. Appropriate therapy was defined as DAPT with prescribed daily doses for each drug covering at least 75% of each individual follow-up period. The association between discharge ward type and antiplatelet therapy adherence at 12 months post discharge was estimated using multilevel logistic regression analysis.

RESULTS

A total of 11 186 patients with PCI were included, and fewer than half (4984; 44.56%) were on adequate DAPT. Only 2930 of 5390 patients (54.36%) with DAPT in the first 6 months post discharge continued DAPT in the second 6 months. Patients discharged from cardiology units or intensive coronary care units were more likely (odds ratio = 1.26; P = 0.003) to receive appropriate antiplatelet therapy, and elderly patients were less likely (odds ratio = 0.65; P < 0.001) to do so.

CONCLUSION

The proportion of PCI patients receiving appropriate DAPT after discharge is suboptimal in this region, and elderly patients are less likely to receive appropriate therapy. These findings could be important for improving patient management and ensuring adherence to clinical guidelines and indicate the need for a systematic evaluation of the appropriateness of postdischarge therapy.

On-treatment platelet reactivity: State of the art and perspectives

High on-clopidogrel platelet reactivity (HcPR) during dual-antiplatelet therapy is a marker of vascular risk, in particular stent thrombosis, in patients with acute coronary syndromes (ACS). Genetic determinants (CYP2C19*2 polymorphism), advanced age, female gender, diabetes and reduced ventricular function are related to a higher risk to develop HcPR. In addition, inflammation and increased platelet turnover, as revealed by the elevated percentage of reticulated platelets in patients' blood, that characterize the acute phase of acute coronary syndromes, are associated with HcPR. To overcome the limitation of clopidogrel, new antiplatelet agents (prasugrel and ticagrelor) were developed and the demonstration of their superiority over clopidogrel was obtained in the two randomized trials, TRITON TIMI 38 and PLATO. Emerging evidence is accumulating on the role of high-on aspirin platelet reactivity (HaPR), especially in the clinical context of diabetes. Finally, the presence of new, potent antiplatelet drugs has shifted the focus from thrombotic to bleeding risk. Recent data document that low on-treatment platelet reactivity (LPR) is associated with a significantly higher bleeding risk. Due to the current possibility to choose between multiple antiplatelet strategies, the future perspective is to include in the management of ACS, in addition to clinical data and classical risk factors, the definition of platelet function during treatment in order to set a tailored therapy.

Safety of prasugrel in real-world patients with ST-segment elevation myocardial infarction: 1-year results from a prospective observational study (Bleeding and Myocardial Infarction Study)

BACKGROUND

Antiplatelet therapies, including prasugrel, are a cornerstone in the treatment of ST-segment elevation myocardial infarction (STEMI), but are associated with a bleeding risk. This risk has been evaluated in randomized trials, but few data on real-world patients are available.

AIM

To evaluate prasugrel safety in real-world patients with STEMI.

METHODS

Consecutive patients with STEMI were recruited over 1 year. Follow-up was done at 3 months and 1 year to evaluate prasugrel safety from hospital discharge to the STEMI anniversary date. The primary outcome was occurrence of any major bleeding according to the Bleeding Academic Research Consortium (BARC) 3 or 5 definitions, or minor bleeding according to the BARC 2 definition.

RESULTS

Overall, 1083 patients were recruited. Compared to patients treated with aspirin+clopidogrel, patients treated with aspirin+prasugrel had fewer BARC 3 or 5 bleedings (two [0.4%] patients vs. nine [1.8%] patients; P=0.04), but more BARC 2 bleedings (45 [9.3%] patients vs. 20 [4.0%] patients; P<0.001). The baseline characteristics of prasugrel- and clopidogrel-treated patients differed because the former were carefully selected (younger, higher body mass index, less frequent history of stroke). In the overall population, rates of in-hospital and out-of-hospital major bleeding were 2.6% (n=28) and 1.3% (n=13), respectively.

CONCLUSION

The rate of major bleeding, particularly out-of-hospital bleeding, in patients treated with prasugrel is low within 1 year after a STEMI. Accurate selection of patient candidates for prasugrel is likely to have reduced the risk of bleeding.

Mean platelet volume and high-residual platelet reactivity in patients receiving dual antiplatelet therapy with clopidogrel or ticagrelor

OBJECTIVE

High on-treatment platelet reactivity (HRPR) is associated with a two- to ninefold increased risk of recurrent ischemic events among patients receiving dual antiplatelet therapy (DAPT) for coronary artery disease. However, its determinants are still poorly understood. The aim of the present study was to assess the impact of mean platelet volume (MPV) on platelet reactivity in patients receiving DAPT after an acute coronary syndrome or PCI.

METHODS

Patients treated with DAPT (acetylsalicylic acid [ASA] and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30 - 90 days post-discharge. By whole blood impedance aggregometry, HRPR was considered for ASPI test > 862 aggregation units (AU)*min (for ASA) and ADP test values ≥ 417 AU*min (for ADP-antagonists).

RESULTS

Our population is represented by a total of 487 patients on DAPT, divided according to MPV tertiles (< 10.4 fl; 10.4 - 11.29 fl; ≥ 11.3 fl). Larger-sized platelets were associated with use of statins (p < 0.001) and beta-blockers (p = 0.03), higher hemoglobin levels (p = 0.002) and lower platelets count (p < 0.001). Higher platelet reactivity was observed at ASPI test in patients with higher MPV (r = 0.12, p = 0.008), but not for ADP-mediated aggregation (r = -0.007, p = 0.88). However, a low prevalence of HRPR was observed with ASA, with no impact of MPV tertiles (1.2 vs 1.1 vs 1.6%, p = 0.70, adjusted OR [95% CI] = 1.05 [0.51 - 1.77], p = 0.87). MPV did not influence the prevalence of HRPR for ADP-antagonists (25.9 vs 1 vs 26.5%, p = 0.89; adjusted OR [95% CI] = 1.1 [0.84 - 1.45], p = 0.50) with similar results among the 259 patients receiving clopidogrel (adjusted OR [95% CI] = 1.15 [0.82 - 1.62], p = 0.43) and the 228 patients on ticagrelor (adjusted OR [95% CI] = 1.46 [0.84 - 2.55], p = 0.18).

CONCLUSION

In patients receiving DAPT, MPV does not affect the response to major antiplatelet therapies. In fact, MPV elevation does not influence the risk of HRPR with clopidogrel, ticagrelor or ASA.

Personalized antiplatelet therapy with P2Y12 receptor inhibitors: benefits and pitfalls

Antiplatelet therapy with P2Y₁₂ receptor inhibitors has become the cornerstone of medical treatment in patients with acute coronary syndrome, after percutaneous coronary intervention and in secondary prevention of atherothrombotic events. Clopidogrel used to be the most broadly prescribed P2Y₁₂ receptor inhibitor with undisputable benefits especially in combination with aspirin, but a considerable number of clopidogrel-treated patients experience adverse thrombotic events in whom insufficient P2Y₁₂-inhibition and a consequential high on-treatment platelet reactivity is a common finding. This clinically relevant limitation of clopidogrel has driven the increased use of new antiplatelet agents. Prasugrel (a third generation thienopyridine) and ticagrelor (a cyclopentyl-triazolo-pyrimidine) feature more potent and predictable P2Y₁₂-inhibition compared to clopidogrel, which translates into improved ischemic outcomes. However, excessive platelet inhibition and consequential low on-treatment platelet reactivity comes at the price of increased risk of major bleeding. The majority of randomized clinical trials failed to demonstrate improved clinical outcomes with platelet function testing and tailored antiplatelet therapy, but results of all recent trials of potent antiplatelets and prolonged antiplatelet durations point towards a need for individualized antiplatelet approach in order to decrease thrombotic events without increasing bleeding. This review focuses on potential strategies for personalizing antiplatelet treatment.

Lower loading dose of prasugrel compared with conventional loading doses of clopidogrel and prasugrel in korean patients undergoing elective coronary angiography: a randomized controlled study evaluating pharmacodynamic efficacy

Background and Objectives

Although prasugrel allows for rapid and potent platelet inhibition, the efficacy and safety of lower doses of prasugrel for patients of East Asian ethnicity has not yet been investigated. We compared the effect of a lower loading dose (LD) of prasugrel with conventional LDs of clopidogrel and prasugrel in Korean patients.

Subjects and Methods

Forty-three Korean patients undergoing coronary angiography were enrolled in the study. Participants were randomly administered LDs of clopidogrel 600 mg, prasugrel 30 mg or prasugrel 60 mg prior to coronary angiography. Platelet reactivity was assessed at baseline and at the time of peak platelet inhibition using light transmission aggregometry (LTA), the VerifyNow assay, and multiple electrode aggregometry.

Results

Although baseline platelet reactivity between the groups showed no significant differences, at the time of peak platelet inhibition, the prasugrel 30 mg (18.9±10.0%) and 60 mg groups (13.8±10.8%) showed significantly more potent platelet inhibition than the clopidogrel 600 mg group (52.9±15.8%; p<0.001) by LTA. However, there were no significant differences between the prasugrel 30 mg and 60 mg groups (p=0.549).

Conclusion

The loading effect of prasugrel 30 mg was more potent than clopidogrel 600 mg and was not significantly different from prasugrel 60 mg.

Impact of obesity and the metabolic syndrome on response to clopidogrel or prasugrel and bleeding risk in patients treated after coronary stenting

This study aimed to analyze the impact of body mass index (BMI) and the metabolic syndrome (MS) on responses to clopidogrel or prasugrel and bleeding risk after acute coronary syndrome. The study included 1,542 consecutive patients who underwent coronary stenting (287 clopidogrel 75 mg, 868 clopidogrel 150 mg, and 387 prasugrel 10 mg). Platelet reactivity was assessed 1 month after discharge using platelet reactivity index vasodilator stimulated phosphoprotein (PRI VASP). Three hundred thirty-six patients (21.8%) were obese (BMI ≥30), and we observed higher platelet reactivity associated with higher BMI across thienopyridine regimens. Incidence of high on-treatment platelet reactivity (PRI VASP >50%) was higher in obese than nonobese patients (p <0.05 for all regimens). Conversely, incidence of low on-treatment platelet reactivity with prasugrel therapy (PRI VASP <20%) was lower in obese than nonobese patients: 13% (12 of 93) versus 33% (97 of 294); odds ratio 0.30, 95% confidence interval 0.16 to 0.58; p <0.001. Accordingly, incidence of Bleeding Academic Research Consortium bleeding complications was higher in nonobese than in obese patients: 10% (119 of 1,206) versus 6% (20 of 336); odds ratio 1.7, 95% confidence interval 1.1 to 2.8; p = 0.03. This impaired response was only observed in obese patients with the MS, and obese with the MS had significantly higher platelet reactivity than other obese patients with all regimens (p <0.01). Obese patients without the MS had no significant difference in platelet reactivity compared with nonobese patients. In conclusion, the present study confirmed that BMI has a strong impact on response to clopidogrel and prasugrel with higher incidence of high on-treatment platelet reactivity, lower incidence of low on-treatment platelet reactivity, and lower bleeding complication in obese patients. However, among obese patients, the presence of the MS strongly affects response to antiplatelet agents, indicating that the metabolic status might be a better predictor of platelet inhibition than BMI.

The Role of Platelet Function Testing in Risk Stratification and Clinical Decision-Making

Clopidogrel (a widely used second-generation thienopyridine) therapy is associated with an unpredictable pharmacodynamic response whereby approximately 1 in 3 patients will have a high on-treatment platelet reactivity to adenosine diphosphate. High on-treatment platelet reactivity is an established risk factor for ischemic event occurrence in patients undergoing percutaneous coronary intervention. Platelet function testing may have a role in monitoring therapeutic efficacy when clopidogrel is the chosen agent and in safety when more potent drugs are used, especially in patients with high bleeding risk. At this time, it seems most reasonable to assess platelet function in high-risk clopidogrel-treated patients.

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

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

Assessing post-treatment platelet reactivity: a focus on patient selection and setting

Dual antiplatelet therapy is critical to inhibit platelet reactivity in order to prevent ischemic recurrences in stented patients. However, studies have observed a variable blockade of the P2Y12 adenosine diphosphate receptor between patients following clopidogrel intake. This interindividual variability in the biological response is not uncommon with clopidogrel (about 50%) and even prasugrel (20%). High on-treatment platelet reactivity (HTPR) is correlated with thrombotic events following percutaneous coronary intervention. Several studies suggested that tailoring of antiplatelet therapy based on platelet reactivity (PR) monitoring could safely reduce the rate of major adverse cardiovascular events in HTPR patients. In addition, low on-treatment PR was recently associated with bleeding events both in patients treated with prasugrel and clopidogrel. Of importance, bleedings are associated with a poor prognosis in stented patients. Overall, the potential of PR monitoring to individualize antiplatelet therapy might benefit stented patients by reducing both ischemic and bleeding risks. However, such strategies remain to be evaluated in adequately designed large-scale randomized clinical trials.