Effect of platelet inhibition with cangrelor during PCI on ischemic events

Periprocedural Myocardial Infarction in Contemporary Practice

"Periprocedural myocardial infarction (MI) occurs infrequently in the current era of percutaneous coronary interventions (PCI) and is associated with an increased risk of mortality and morbidity. Periprocedural MI can occur due to acute side branch occlusion, distal embolization, slow flow or no reflow phenomenon, abrupt vessel closure, and nonidentifiable mechanical processes. Therapeutic strategies to reduce the risk of periprocedural MI include dual antiplatelet therapy, intravenous cangrelor in the periprocedural setting, intravenous glycoprotein IIb/IIIa inhibitor in high-risk patients, anticoagulation with unfractionated heparin, low-molecular-weight heparin or bivalirudin, and embolic protection devices during saphenous vein graft interventions."

A study on structural characterization of degradation products of cangrelor using LC/QTOF/MS/MS and NMR

A complete degradation study was performed on cangrelor drug substance as per the ICH guidelines. The study reveals that a total of six degradation products (DP-1 to DP-6) were found and out of these, three unknown degradation products (DP-1, DP-5 and DP-6) were not reported in the literature. Based on the degradation study, the drug substance cangrelor was found to be sensitive towards acidic, basic and oxidative conditions. Besides, it was stable under thermal and photolytic stress conditions. The degradation products were characterized by using advanced LC/QTOF and MS/MS analysis. Further, the structures were characterized by NMR studies. The identified degradation products of cangrelor are valuable for cangrelor manufacturing process and quality control.

Switching between P2Y12 inhibitors: Rationale, methods, and expected consequences

The pharmacological and clinical differences of the three recommended oral P2Y₁₂ inhibitors (clopidogrel, prasugrel, ticagrelor) enable physicians to switch from one agent to another that it is considered more appropriate in the specific clinical setting. Moreover, the recent availability of cangrelor, the only intravenous P2Y₁₂ inhibitor with a rapid onset and offset of its antiplatelet action, makes it necessary to switch from this agent to an oral P2Y₁₂ inhibitor for a continued platelet inhibition after percutaneous coronary intervention. Several pharmacodynamic studies have provided information on how to change drug, in terms of timing and dosage, without running the risk of a temporary impairment of platelet inhibition. In addition, several studies have assessed the impact of the switching between P2Y₁₂ inhibitors on clinical outcomes. Overall, these evidences have prompted the development of an extensive expert consensus document, have set the basis for recent practice guidelines recommendations, and have stimulated several systematic overviews. The present article provides a brief and schematic summary on the topic of switching between P2Y₁₂ inhibitors, focusing on three main practical issues: why and how to switch therapies and what are the clinical consequences of such strategy.

Use of Cangrelor as a Bridge to Left Ventricular Assist Device Implantation in a Patient with a Recent Drug-Eluting Stent Who Developed Acute Tirofiban-Related Thrombocytopenia

Current guidelines emphasize the need for at least 6-12 months of oral dual antiplatelet therapy consisting of aspirin and a P2Y12 inhibitor following drug-eluting coronary artery stent implantation. In patients with recently implanted coronary artery stents who require urgent cardiac or noncardiac surgery, the benefits of maintaining oral dual antiplatelet therapy must be carefully weighed against the risks of excessive bleeding, and current practice is largely guided by individual surgeon preferences. When the effects of a second oral antiplatelet agent are undesirable during the perioperative period, the use of a short-acting intravenous antiplatelet agent as "bridge" therapy that can be discontinued shortly before surgery is associated with a reduced occurrence of adverse clinical events in patients with recently implanted coronary stents requiring urgent coronary artery bypass graft surgery. Cangrelor is an intravenous adenosine triphosphate analog P2Y12 receptor antagonist with a short plasma half-life that has been used off label in patients with recent coronary stents as a bridge to invasive procedures with excessive bleeding risk. To our knowledge, this is the first case report to demonstrate the safe and effective use of cangrelor as a bridge to left ventricular assist device implantation in a patient with a recently implanted drug-eluting coronary artery stent who developed acute thrombocytopenia following reexposure to tirofiban, a glycoprotein IIb/IIIa inhibitor.

Effect of morphine use on oral P2Y12 platelet inhibitors in acute myocardial infarction: Meta-analysis

BACKGROUND

Morphine is the recommended analgesic in acute myocardial infarction (AMI). This recommendation has come under scrutiny because of possible slow uptake of oral antiplatelet agents.

OBJECTIVE

We performed a meta-analysis of all available studies in AMI patients treated with prasugrel or ticagrelor (P2Y12 inhibitors) that reported use of morphine prior to loading the antiplatelet agents to critically assess the safety of co-administration of morphine and the newer P2Y12 inhibitors.

METHODS

Several sources were searched from inception to December 2017 with inclusion of eight studies, largely observational. Mean difference (MD) was calculated for continuous variables, and standardized mean difference (SMD) for platelet function was assessed by the various platelet assays, 2 h after the loading dose of oral P2Y12 inhibitors.

RESULTS

Higher platelet activity was noted among morphine group [SMD = 0.8, 95% confidence interval (CI) = 0.4-1.1, p < 0.01]. Morphine use caused higher odds of "high residual platelet reactivity" at 2 h (odds = 3.3, 95 %CI = 2.2-5.1, p < 0.01). Ticagrelor reached a lower plasma concentration in morphine group (MD = -481.8 ng/ml, 95% CI = -841.2 to -122.4 ng/ml, p < 0.01) with a higher vomiting rate (odds = 5.3, 95% CI = 2.5-11.1, p < 0.01). However, the composite of in-hospital mortality, stroke, and re-infarction was not significantly different between the groups (p = 0.83).

CONCLUSION

Co-administration of morphine with P2Y12 inhibitors possibly decreases their efficacy in platelet inhibition. However, this did not translate into higher adverse outcomes because of low event rates, inadequate for analysis. A large randomized study is needed to evaluate the narcotic-P2Y12 interaction.

Cangrelor in cardiogenic shock and after cardiopulmonary resuscitation: A global, multicenter, matched pair analysis with oral P2Y12 inhibition from the IABP-SHOCK II trial

AIMS

Cangrelor has a potentially favorable pharmacodynamic profile in cardiogenic shock (CS). We aimed to evaluate the clinical course of CS patients undergoing percutaneous coronary intervention (PCI) treated with cangrelor.

METHODS AND RESULTS

We retrospectively identified 136 CS patients treated with cangrelor. Patients were 1:1 matched to CS patients from the IABP-SHOCK II trial not receiving cangrelor by age, sex, cardiac arrest, type of myocardial infarction, culprit lesion, glycoprotein IIb/IIIa inhibitor, and oral P2Y₁₂-receptor inhibitor and followed-up for 12 months. The study cohort consisted of 88 matched pairs. Thirty-day and 12-month mortality was 29.5% and 34.1% in cangrelor-treated patients and 36.4% and 47.1% in control group (P = 0.34 and P = 0.08, respectively). The rate of definite acute stent thrombosis was 2.3% in both groups. Moderate and severe bleeding events occurred in 21.6% in the cangrelor and 19.3% in the control group (P = 0.71). Patients treated with cangrelor more frequently experienced ≥1 TIMI flow grade improvement during PCI (92.9% vs. 81.2%, P = 0.02).

CONCLUSION

Cangrelor treatment was associated with similar bleeding risk and significantly better TIMI flow improvement compared with oral P2Y₁₂ inhibitors in CS patients undergoing PCI. The use of cangrelor in CS offers a potentially safe and effective antiplatelet option and should be evaluated in randomized trials.

A randomised, investigator-initiated, clinical trial of the effects of fentanyl on P2Y12-receptor inhibition in patients with ST-elevation myocardial infarction who are pre-treated with crushed ticagrelor: rationale and design of the Opioids aNd crushed Ticagrelor In Myocardial infarction Evaluation (ON-TIME 3) trial

Background

Fast and accurate platelet inhibition is an important therapeutic goal in the acute treatment of patients with ST-elevation myocardial infarction (STEMI). Platelet inhibitory effects induced by oral P2Y12-receptor antagonists are delayed in STEMI patients undergoing primary percutaneous coronary intervention (PCI) due to haemodynamic changes and delayed gastro-intestinal absorption. Concomitant use of opioids, although recommended in the American College of Cardiology/American Heart Association and European Society of Cardiology STEMI guidelines, further delays gastro-intestinal absorption. To date, trials investigating alternative analgesics in STEMI patients have been scarce. This trial aims to assess the feasibility of a novel drug strategy for treatment of STEMI patients with crushed ticagrelor in combination with paracetamol (acetaminophen) instead of opioids.

Hypothesis

STEMI patients who are pre-treated with crushed ticagrelor and paracetamol have a higher level of platelet inhibition after primary PCI than patients pre-treated with crushed ticagrelor and fentanyl.

Study design

The Opioids aNd crushed Ticagrelor In Myocardial infarction Evaluation (ON-TIME 3) trial is a randomised controlled trial designed to examine whether administration of paracetamol instead of fentanyl can optimise platelet inhibition in STEMI patients who are pre-treated with crushed ticagrelor in the ambulance. One hundred and ninety patients with STEMI will be randomised (1:1 fashion) to intravenous (IV) fentanyl or IV paracetamol. The primary endpoint is the level of platelet reactivity units measured immediately after primary PCI.

Summary

The ON-TIME 3 trial (NCT03400267) aims to achieve optimal platelet inhibition and pain relief in STEMI patients receiving crushed ticagrelor in the ambulance by investigating IV fentanyl and IV paracetamol as analgesics.

Metabolic Alterations in Cardiopulmonary Vascular Dysfunction

Cardiovascular diseases (CVD) are the leading cause of death worldwide. CVD comprise a range of diseases affecting the functionality of the heart and blood vessels, including acute myocardial infarction (AMI) and pulmonary hypertension (PH). Despite their different causative mechanisms, both AMI and PH involve narrowed or blocked blood vessels, hypoxia, and tissue infarction. The endothelium plays a pivotal role in the development of CVD. Disruption of the normal homeostasis of endothelia, alterations in the blood vessel structure, and abnormal functionality are essential factors in the onset and progression of both AMI and PH. An emerging theory proposes that pathological blood vessel responses and endothelial dysfunction develop as a result of an abnormal endothelial metabolism. It has been suggested that, in CVD, endothelial cell metabolism switches to higher glycolysis, rather than oxidative phosphorylation, as the main source of ATP, a process designated as the Warburg effect. The evidence of these alterations suggests that understanding endothelial metabolism and mitochondrial function may be central to unveiling fundamental mechanisms underlying cardiovascular pathogenesis and to identifying novel critical metabolic biomarkers and therapeutic targets. Here, we review the role of the endothelium in the regulation of vascular homeostasis and we detail key aspects of endothelial cell metabolism. We also describe recent findings concerning metabolic endothelial cell alterations in acute myocardial infarction and pulmonary hypertension, their relationship with disease pathogenesis and we discuss the future potential of pharmacological modulation of cellular metabolism in the treatment of cardiopulmonary vascular dysfunction. Although targeting endothelial cell metabolism is still in its infancy, it is a promising strategy to restore normal endothelial functions and thus forestall or revert the development of CVD in personalized multi-hit interventions at the metabolic level.

Perioperative Bridging With Glycoprotein IIb/IIIa Inhibitors Versus Cangrelor: Balancing Efficacy and Safety

OBJECTIVE

To review the efficacy and safety of perioperative administration of intravenous (IV) antiplatelet agents as a substitute for oral P2Y₁₂ inhibitors and to provide clinicians guidance on optimal and cost-effective use of these medications.

DATA SOURCES

A MEDLINE literature search (1950 to November 2018) was performed using the key search terms abciximab, bridging, cangrelor, cardiac surgery, coronary artery bypass surgery, eptifibatide, intravenous antiplatelet agent, and tirofiban. Additional references were identified from a review of literature citations.

STUDY SELECTION AND DATA EXTRACTION

In all, 18 original research reports and case reports/series were included in the review.

DATA SYNTHESIS

Prevention of postoperative bleeding is critical to decrease morbidity and mortality after cardiac surgery. IV antiplatelet medications have short half-lives and are frequently used to substitute for oral P2Y₁₂ inhibitors to allow platelet function recovery before procedures. Functional recovery of platelets is delayed after abciximab discontinuation and increases postoperative bleeding risk. Eptifibatide and tirofiban have similar pharmacokinetic/pharmacodynamic properties and comparable efficacy and safety in the setting of perioperative bridging. Cangrelor may be considered in patients with renal insufficiency as decreased clearance of eptifibatide or tirofiban may increase the risk of postoperative bleeding. Relevance to Patient Care and Clinical Practice: Comparative studies of IV antiplatelet medications have not been published. Appropriate use of IV antiplatelet medications can prevent perioperative ischemic events and bleeding.

CONCLUSIONS

Eptifibatide, tirofiban, and cangrelor are preferred over abciximab as a perioperative bridge. The choice of agent should be tailored to clinical characteristics of the patient and institutional acquisition costs.

Intravenous antiplatelet therapies (glycoprotein IIb/IIIa receptor inhibitors and cangrelor) in percutaneous coronary intervention: from pharmacology to indications for clinical use

Oral antiplatelet drugs are crucially important for patients with acute coronary syndrome or stable coronary artery disease undergoing percutaneous coronary intervention (PCI). In recent decades, several clinical trials have focused on reducing periprocedural ischemic events in patients undergoing PCI by means of more rapid platelet inhibition with the use of intravenous antiplatelet drugs. Glycoprotein IIb/IIIa receptor inhibitors (GPIs) block the final common pathway of platelet aggregation and enable potent inhibition in the peri-PCI period. In recent years, however, the use of GPIs has decreased due to bleeding concerns and the availability of more potent oral P2Y12 inhibitors. Cangrelor is an intravenous P2Y12 receptor antagonist. In a large-scale regulatory trial, cangrelor administration during PCI allowed for rapid, potent and rapidly reversible inhibition of platelet aggregation, with an anti-ischemic benefit and no increase in major bleeding. This article aims to provide an overview of general pharmacology, supporting evidence and current status of intravenous antiplatelet therapies (GPIs and cangrelor), with a focus on contemporary indications for their clinical use.

Do We Need Potent Intravenous Antiplatelet Inhibition at the Time of Reperfusion During ST-Segment Elevation Myocardial Infarction?

Acute myocardial infarction (MI) is still a large source of morbidity and mortality worldwide. Although early reperfusion therapy has been prioritized in the modern era of percutaneous coronary intervention and thrombolysis, attempts at incremental improvements in clinical outcomes by reducing MI size have not been successful so far. Herein, we review the studies that have evaluated immediate-onset antiplatelet therapy as attempts to improve meaningful clinical outcomes in ST-segment elevation MI (STEMI). Unfortunately, many of the adjunctive pharmacotherapies have proven to be disappointing. Recent studies performed in the background of routine oral administration of P2Y₁₂ adenosine receptor inhibitors, which may take several hours to take full effect, and aspirin have largely shown no improvement in outcomes, despite an earlier onset of antiplatelet activity of the investigative agents. Further progress in improving outcomes during STEMI may depend on exploring therapeutics that modulate the pathophysiology of microvascular damage during ischemia-reperfusion injury, a phenomenon whose effects evolve over hours to days. We speculate that the dynamic nature of the no-reflow phenomenon may be an explanation for these disappointing results with the intravenous antiplatelet agents. We hope that appreciation for what has not worked in this domain may direct future research efforts to focus on novel pathways. Myocardial ischemia and reperfusion injury are very much still a lingering issue. Despite significant improvements in door-to-balloon times, rates of in-hospital mortality for STEMI remain unchanged. Outcomes following successfully reperfused STEMI are likely determined by the initial size of myocardial necrosis (ie, cardiomyocyte death during the period of ongoing ischemia), patency of the infarct-related epicardial coronary artery, possible reperfusion injury, the microvascular no-reflow phenomenon, and adverse remodeling after infarction.

Platelet inhibition to target reperfusion injury trial: Rationale and study design

BACKGROUND

In ST-segment elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PPCI), current oral P2Y12 platelet inhibitors do not provide maximal platelet inhibition at the time of reperfusion. Furthermore, administration of cangrelor prior to reperfusion has been shown in pre-clinical studies to reduce myocardial infarct (MI) size. Therefore, we hypothesize that cangrelor administered prior to reperfusion in STEMI patients will reduce the incidence of microvascular obstruction (MVO) and limit MI size in STEMI patients treated with PPCI.

METHODS

The platelet inhibition to target reperfusion injury (PITRI) trial, is a phase 2A, multi-center, double-blinded, randomized controlled trial, in which 210 STEMI patients will be randomized to receive either an intravenous (IV) bolus of cangrelor (30 μg/kg) followed by a 120-minute infusion (4 μg/kg/min) or matching saline placebo, initiated prior to reperfusion (NCT03102723).

RESULTS

The study started in October 2017 and the anticipated end date would be July 2020. The primary end-point will be MI size quantified by cardiovascular magnetic resonance (CMR) on day 3 post-PPCI. Secondary endpoints will include markers of reperfusion, incidence of MVO, MI size, and adverse left ventricular remodeling at 6 months, and major adverse cardiac and cerebrovascular events.

SUMMARY

The aim of the PITRI trial is to assess whether cangrelor administered prior to reperfusion would reduce acute MI size and MVO, as assessed by CMR.

Safety and efficacy of cangrelor in acute stenting for the treatment of cerebrovascular pathology: preliminary experience in a single-center pilot study

BACKGROUND

Treatment of acute cerebrovascular pathology, such as acute ischemic stroke or intracranial aneurysms, presents a challenge if an extracranial or intracranial stent is required; immediate platelet inhibition is vital. To date, there is no standardized approach for antiplatelet inhibition in an acute setting.

OBJECTIVE

To report our preliminary experience and lessons learnt using cangrelor in acute neurointervention.

METHODS

A single-arm pilot study was performed to assess the safety and efficacy of cangrelor plus aspirin for platelet inhibition in patients who require acute stenting in the setting of neuroendovascular treatment.

RESULTS

Eight patients were enrolled between October 2017 and August 2018. Median age was 71 years (53-86). Seven patients were treated in an acute setting according to the stroke protocol at our institution, while one patient was treated for a symptomatic, unruptured aneurysm with flow diversion and coiling. At admission, the median National Institutes of Health Stroke Scale score for the patients with stroke was 12.5 (range 2-22.3). Cangrelor was infused and all patients achieved adequate platelet inhibition (<200 PRU (P2Y12 reaction units)). Six of seven patients with ischemic stroke had a carotid stent placed and one had an intracranial stent deployed in the middle cerebral artery. None of the patients experienced intraprocedural thromboembolic complications, intraprocedural in-stent thrombosis, hemorrhagic complications, or stroke within 24 hours after the intervention. The majority of patients (6/8) had a good clinical outcome at discharge (modified Rankin Scale score 0-2).

CONCLUSIONS

Our findings suggest that cangrelor is a promising alternative in acute stenting for the treatment of cerebrovascular pathology. However, further studies with larger samples are required to accurately elucidate its safety and effectiveness in neuroendovascular procedures.

The promise of effective P2Y12 platelet receptor pretreatment: Not crushed yet

Pre-treatment with intact oral clopidogrel and prasugrel tablets in a representative observational study is not associated with altered ischemic or bleeding outcomes in acute coronary syndrome (ACS) patients. Limited by cost, cangrelor, a rapidly acting intravenous P2Y₁₂ platelet receptor inhibitor, achieved meaningful reductions in major adverse cardiovascular events (MACE) and stent thrombosis (ST) compared to oral clopidogrel pretreatment. Crushed prasugrel and ticagrelor (CP&T) administered orally achieve accepted thresholds of therapeutic platelet inhibition in one hour in approximately 2/3rds of patients compared to 1/3rd with intact oral tablets. A large, simple randomized trial should test whether CP&T pre-treatment could capture some of the potential outcome benefit of rapid P2Y₁₂ inhibition at no incremental risk and cost.

Effect of P2Y12 inhibitors on thrombus stability and endogenous fibrinolysis

Although used routinely to reduce thrombotic events in patients with coronary disease, the effects of P2Y₁₂ inhibitors on thrombus stability and endogenous fibrinolysis are largely unknown. Blood taken from patients pre- and post-aspirin (n = 20) and on aspirin alone and on dual antiplatelet therapy comprising aspirin plus clopidogrel (n = 20), ticagrelor (n = 20) or cangrelor (n = 20), was tested using the Global Thrombosis Test. The number of "rebleeds" or drops (D) after early platelet-rich thrombus formation (occlusion time, OT), and before final lasting occlusion, was used as an inverse measure of thrombus stability. Whilst clopidogrel had no effect, ticagrelor and cangrelor both increased D significantly, reflecting increased thrombus instability [D pre- and post-clopidogrel 4.3 ± 1.6 vs. 4.5 ± 1.4, p = 0.833; pre- and post-ticagrelor 4.1 ± 2.4 vs. 6.8 ± 5.1, p = 0.048; pre- and post-cangrelor 3.6 ± 2.0 vs. 7.9 ± 8.9, p = 0.046]. Platelet reactivity was reduced by all P2Y₁₂ inhibitors, demonstrated by OT prolongation (clopidogrel 378 ± 87 s vs. 491 ± 93 s, p < 0.001; ticagrelor 416 ± 122 s vs. 549 ± 121 s, p < 0.001; cangrelor 381 ± 146 s vs. 613 ± 210 s, p < 0.001). The magnitude of OT prolongation compared to baseline (ΔOT) was significantly greater for cangrelor compared to clopidogrel and ticagrelor. Cangrelor was the only agent to enhance fibrinolysis (lysis time pre- and post-cangrelor 1622[1240-2048]s vs. 1388[960-1634]s, p = 0.005). We demonstrate the ability to assess the effect of pharmacotherapy on thrombus stability in vitro and show that P2Y₁₂ inhibitors potentiate thrombus instability at high shear. Cangrelor, and to a lesser extent ticagrelor, de-stabilised thrombus formation and cangrelor also enhanced fibrinolysis. Potentiation of thrombus instability could become a new pharmacological target, that may be particularly important in acute coronary syndromes.

Characteristics and outcomes of patients requiring bailout use of glycoprotein IIb/IIIa inhibitors for thrombotic complications of percutaneous coronary intervention: An analysis from the CHAMPION PHOENIX trial

AIMS

To describe the characteristics and outcomes of patients receiving bailout glycoprotein IIb/IIIa inhibitors (GPI) for thrombotic complications of percutaneous coronary intervention (PCI) in a large, contemporary trial.

METHODS AND RESULTS

In the CHAMPION PHOENIX trial, the use of GPI was restricted to bailout for thrombotic complications. We describe the characteristics and outcomes of patients requiring bailout GPI compared to patients not receiving GPIs, with adjustment through propensity-score. A multivariable model was constructed to identify independent correlates associated with bailout GPI use. A total of 380 out of 10,942 patients received GPI (3.5%); GPI patients were younger, more frequently male, more likely to present with ST segment elevation myocardial infarction and less frequently treated with cangrelor. At 48 h, GPI patients experienced higher rates of the primary composite outcome of death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis (ST) (19.2% vs 4.8%; adjusted OR: 5.65(4.08, 7.82), p < 0.0001) and a higher rate of GUSTO severe or moderate bleeding (2.6% vs 0.4% adjusted OR: 4.90 (1.98, 12.18), p = 0.0006) compared with non GPI patients. Independent correlates of GPI use were STEMI, use of unfractionated heparin, drug-eluting stents and longer procedure duration.

CONCLUSIONS

In a large contemporary trial, patients receiving bailout GPI for thrombotic complications of PCI experienced very high risks of both ischemic and bleeding complications, suggesting that prevention of periprocedural complications rather than bailout GPI may be preferable.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov identifier: NCT01156571.

Switching P2Y12 Receptor Inhibiting Therapies

Antiplatelet therapy with aspirin and a P2Y₁₂ receptor inhibitor is the cornerstone of treatment of patients with atherothrombotic disease manifestations. Switching between P2Y₁₂ inhibitors occurs commonly in clinical practice for a variety of reasons, including safety, efficacy, adherence, and economic considerations. There are concerns about the optimal approach for switching because of potential drug interactions, which may lead to ineffective platelet inhibition and thrombotic complications, or potential overdosing due to overlap in drug therapy, which might cause excessive platelet inhibition and increased bleeding. This review provides practical considerations of switching based on pharmacodynamic and clinical data available from the literature.

Cangrelor: Pharmacology, Clinical Data, and Role in Percutaneous Coronary Intervention

In clinical trials that assessed the safety and efficacy of cangrelor during percutaneous coronary intervention (PCI), cangrelor was administered as a 30-μg/kg bolus followed by a 4-μg/kg/min infusion for at least 2 hours or the duration of the PCI, whichever was longer. Cangrelor is currently indicated as an adjunct to PCI to reduce the risk of myocardial infarction, repeat coronary revascularization, and stent thrombosis in patients who have not been treated with a P2Y₁₂ platelet inhibitor and are not being given a glycoprotein IIb/IIIa inhibitor.

The Range and Scientific Value of Randomized Trials

BACKGROUND

The randomized, controlled trial (RCT) is the gold standard of scientific evidence for the attribution of clinical effects (benefits and harms) to medical interventions. Many different designs for RCTs have been developed in order to counter legitimate critical objections and to better adapt the trials to the continually changing challenges that face clinical research.

METHODS

The diversity and adaptability of randomized trial designs are presented and discussed on the basis of a selective literature review and specific illustrative examples.

RESULTS

A wide range of RCT designs enables adaptation to special research tasks and clinical framework conditions. These include (among others) crossover trials, n=1 trials, factorial RCT designs, and cluster-randomized trials. In addition, adaptive designs such as modern platform trials and pragmatic RCTs with simplified clinical questions and less severely restricted patient groups make broad recruitment of patients possible even in routine clinical practice.

CONCLUSION

Only the randomized allocation of subjects to the treatment and control groups, which is the defining property of RCTs, can adequately ensure that traits of the subjects which might disturb or bias a comparison of two or more medical interventions, will be evenly distributed across groups, regardless of whether these traits are known or unknown. The methodological variants and further elaborations of the RCT that are discussed here will help protect patients by enabling the assessment of the benefits and harms of medical methods and products on the basis of robust evidence even in the present era of rapid innovation.

Bivalirudin versus heparin monotherapy in non-ST-segment elevation myocardial infarction

BACKGROUND

The optimal anti-coagulation strategy for patients with non-ST-elevation myocardial infarction treated with percutaneous coronary intervention is unclear in contemporary clinical practice of radial access and potent P2Y12-inhibitors. The aim of this study was to investigate whether bivalirudin was superior to heparin monotherapy in patients with non-ST-elevation myocardial infarction without routine glycoprotein IIb/IIIa inhibitor use.

METHODS

In a large pre-specified subgroup of the multicentre, prospective, randomised, registry-based, open-label clinical VALIDATE-SWEDEHEART trial we randomised patients with non-ST-elevation myocardial infarction undergoing percutaneous coronary intervention, treated with ticagrelor or prasugrel, to bivalirudin or heparin monotherapy with no planned use of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention. The primary endpoint was the rate of a composite of all-cause death, myocardial infarction or major bleeding within 180 days.

RESULTS

A total of 3001 patients with non-ST-elevation myocardial infarction, were enrolled. The primary endpoint occurred in 12.1% (182 of 1503) and 12.5% (187 of 1498) of patients in the bivalirudin and heparin groups, respectively (hazard ratio of bivalirudin compared to heparin treatment 0.96, 95% confidence interval 0.78-1.18, p=0.69). The results were consistent in all major subgroups. All-cause death occurred in 2.0% versus 1.7% (hazard ratio 1.15, 0.68-1.94, p=0.61), myocardial infarction in 2.3% versus 2.5% (hazard ratio 0.91, 0.58-1.45, p=0.70), major bleeding in 8.9% versus 9.1% (hazard ratio 0.97, 0.77-1.24, p=0.82) and definite stent thrombosis in 0.3% versus 0.2% (hazard ratio 1.33, 0.30-5.93, p=0.82).

CONCLUSION

Bivalirudin as compared to heparin during percutaneous coronary intervention for non-ST-elevation myocardial infarction did not reduce the composite of all-cause death, myocardial infarction or major bleeding in non-ST-elevation myocardial infarction patients receiving current recommended treatments with modern P2Y12-inhibitors and predominantly radial access.

Antithrombotic P2Y12 receptor antagonists: recent developments in drug discovery

The P2Y₁₂ receptor is one of eight known P2Y receptor subtypes, and belongs to the G-protein-coupled receptor (GPCR) family. The P2Y₁₂ receptor is highly expressed on blood platelets and in the brain. Potent, selective, peripherally acting antagonists for the P2Y₁₂ receptor are used clinically as antithrombotic drugs. Several different scaffolds have been identified as P2Y₁₂ receptor antagonists, including irreversibly acting thienotetrahydropyridines (prodrugs), and reversible competitive antagonists, including adenine nucleotide analogs, piperazinyl-glutamate-quinolines, -pyridines, and -pyrimidines, and anthraquinone derivatives. Here, we provide an overview of the different scaffolds that have been developed as P2Y₁₂ receptor antagonists, some of which have become important therapeutics.

GLS-409, an Antagonist of Both P2Y1 and P2Y12, Potently Inhibits Canine Coronary Artery Thrombosis and Reversibly Inhibits Human Platelet Activation

Dual antiplatelet therapy with aspirin and an adenosine diphosphate (ADP) P2Y₁₂ receptor antagonist reduces ischemic events in patients with acute coronary syndrome. Previous evidence from our group, obtained in a preclinical model of recurrent platelet-mediated thrombosis, demonstrated that GLS-409, a diadenosine tetraphosphate derivative that inhibits both P2Y₁ and P2Y₁₂ ADP receptors, may be a novel and promising antiplatelet drug candidate. However, the salutary antiplatelet effects of GLS-409 were accompanied by a trend toward an unfavorable increase in bleeding. The goals of this study were to: 1) provide proof-of-concept that the efficacy of GLS-409 may be maintained at lower dose(s), not accompanied by an increased propensity to bleeding; and 2) establish the extent and kinetics of the reversibility of human platelet inhibition by the agent. Lower doses of GLS-409 were identified that inhibited in vivo recurrent coronary thrombosis with no increase in bleeding time. Human platelet inhibition by GLS-409 was reversible, with rapid recovery of platelet reactivity to ADP, as measured by platelet surface activated GPIIb-IIIa and platelet surface P-selectin. These data support the concept that GLS-409 warrants further, larger-scale investigation as a novel, potential therapy in acute coronary syndromes.

Modern Management of ST-Segment Elevation Myocardial Infarction

Disruption of intracoronary plaque with thrombus formation resulting in severe or total occlusion of the culprit coronary artery provides the pathophysiologic foundation for ST-segment elevation myocardial infarction (STEMI). Management of STEMI focuses on timely restoration of coronary blood flow along with antithrombotic therapies and secondary prevention strategies. The purpose of this review is to discuss the epidemiology, pathophysiology, and diagnosis of STEMI. In addition, the review will focus on guideline-directed therapy for these patients and review potential associated complications.

An update on the use of anticoagulant therapy in ST-segment elevation myocardial infarction

INTRODUCTION

Together with antiplatelet therapy, anticoagulants are vital to improve outcomes in patients presenting with ST-segment elevation myocardial infarction. Challenges lie in finding the optimal balance between the risk of bleeding and preventing thrombotic complications such as reinfarction or stent thrombosis. During the last decade, bivalirudin was introduced as a valid alternative to heparin for patients undergoing primary percutaneous coronary intervention. Several trials have been conducted to identify the agent with the best antithrombotic results at the lowest bleeding complication rate. In a rapidly evolving field with changes in vascular access, available P2Y₁₂ inhibitors, and indications for glycoprotein IIb/IIIa inhibitor administration, conflicting evidence became available.

AREAS COVERED

This paper mainly focuses on the evidence above and gives brief discussion to the recent literature on anticoagulation in fibrinolytic therapy and advances in antiplatelet therapy.

EXPERT OPINION

To date, no robust evidence is available challenging unfractionated heparin as the primary choice for anticoagulation in patients presenting with ST-segment elevation myocardial infarction. Further research should include efforts to refine anticoagulation strategies on an individual patient level. For patients undergoing primary percutaneous coronary intervention, bivalirudin could be used as an alternative to unfractionated heparin, while enoxaparin or fondaparinux is an alternative agent for patients treated with fibrinolytic therapy.

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.

Evaluating current and emerging antithrombotic therapy currently available for the treatment of acute coronary syndrome in geriatric populations

INTRODUCTION

Acute coronary syndromes (ACS) represent one of the most perilous presentations of ischemic heart disease. Temporal trends clearly demonstrate that ACS occur later and later in life. Elderly patients with ACS comprise a populous and growing group, with more than half of individuals presenting with myocardial infarction being 75 years or older. Nevertheless, geriatric patients are greatly underrepresented in the landmark ACS trials evaluating innovative pharmacological strategies.

AREAS COVERED

The authors critically summarize recently published research on contemporary and emerging antithrombotic therapy for the treatment of ACS in geriatric patients.

EXPERT OPINION

Elderly ACS patients are characterized by simultaneously increased risk of cardiovascular events and bleeding. Very few studies assessing the efficacy and safety of novel ACS pharmacotherapy in geriatric patients are currently available. Guidelines on the treatment of ACS are based on the overall results of major randomized clinical trials (RCTs), and data supporting the recommended therapy in elderly mainly derive from subanalyses of these RCTs. Properly designed and powered RCTs are necessary to properly evaluate the net effect of current and emerging pharmacotherapy in geriatric patients. Until such data are available, elderly ACS patients should receive treatment according to the general recommendations.

Cangrelor for the treatment of patients with Arterial Thrombosis

INTRODUCTION

All oral P2Y₁₂ receptor blockers are associated with some degree of delayed onset and offset of pharmacodynamic (PD) effects in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI). Although intravenous glycoprotein IIb/IIIa inhibitors are associated with rapid onset of action, they are also associated with delayed offset and other limitations such as elevated bleeding risk and thrombocytopenia. Areas covered: In this review, the authors focus on cangrelor, an intravenous, reversible P2Y₁₂ receptor blocker with fast onset and offset of effects. The authors also describe the pharmacologic effects of cangrelor and its pharmacologic interaction with other P2Y₁₂ receptor inhibitors. Finally, the authors discuss the large-scale clinical trials that compared the efficacy and safety of cangrelor with clopidogrel. Expert opinion: In ACS patients undergoing PCI, cangrelor is most desirable to effectively prevent periprocedural ischemic events and to avoid excessive bleeding. Indeed, any high-risk patient with ST-segment elevation myocardial infraction or patient who is unable to take oral medications is a potential candidate for intravenous cangrelor therapy. Furthermore, stable patients with coronary artery disease, who are considered for ad hoc PCI following coronary angiography, may be considered for treatment with cangrelor to reduce post-PCI thrombotic events.

Pretreatment with dual antiplatelet therapy in patients with ST-elevation myocardial infarction

BACKGROUND

The optimal time to administer P2Y₁₂ inhibitors in patients with ST-elevation myocardial infarction (STEMI) remains to be defined. We sought to assess whether a pretreatment strategy was associated with improved coronary reperfusion and clinical outcomes.

METHODS

Consecutive patients from the Melbourne Interventional Group registry (2005-2014) who presented with STEMI and underwent primary PCI were included. Those who received any P2Y₁₂ inhibitor prior to arrival in the cardiac catheterisation laboratory were included in the pretreatment group. The primary endpoints were the proportion of patients with initial TIMI flow grade <3 and in-hospital bleeding. The secondary endpoints were 12-month mortality and major adverse cardiovascular events (MACE).

RESULTS

Of the 2,807 patients included, 892(31.8%) received pretreatment. Clopidogrel was the most common P2Y₁₂ inhibitor used (79.6%). Pretreatment was associated with less thromboaspiration and GPIIb/IIIa inhibitor use (both P < 0.01). Pretreatment was not associated with lower rates of TIMI flow <3 on initial angiogram (78.0% vs. 80.7%, P = 0.18) nor with increased in-hospital bleeding (3.6% vs. 3.9%, P = 0.67). Pretreatment was associated with lower 12-month mortality (4.7% vs. 7.0%, P = 0.02) but similar MACE rate (13.0% vs. 14.1%, P = 0.43). Multivariate analysis revealed pretreatment was not an independent predictor of 12-month mortality (OR 0.79; 95% CI 0.5-1.3, P = 0.32).

CONCLUSION

Pretreatment with a P2Y₁₂ inhibitor in patients with STEMI was not routine practice in our Australian cohort and was not associated with improved coronary reperfusion or clinical outcomes. Larger studies are required to definitively ascertain the risk/benefit ratio of dual antiplatelet therapy pretreatment in STEMI.

Antiplatelet and anticoagulation regimen in patients with mechanical valve undergoing PCI - State-of-the-art review

A common clinical dilemma regarding treatment of patients with a mechanical valve is the need for concomitant antiplatelet therapy for a variety of reasons, referred to as triple therapy. Triple therapy is when a patient is prescribed aspirin, a P2Y12 antagonist, and an oral anticoagulant. Based on the totality of the available evidence, best practice in 2017 for patients with mechanical valves undergoing percutaneous coronary intervention (PCI) is unclear. Furthermore, the optimal duration of dual antiplatelet therapy after PCI is evolving. With better valve designs that are less thrombogenic, the thromboembolic risks can be reduced at a lower international normalized ratio target, thus decreasing the bleeding risk. This review will offer an in-depth survey of current guidelines, current evidence, suggested approach for PCI in this cohort, and future studies regarding mechanical valve patients undergoing PCI.

Non-ST-Segment Acute Coronary Syndromes

Acute coronary syndrome (ACS) represents an umbrella of ischemic myocardial disease and diagnoses encompassing unstable angina (UA), non-ST-elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI). UA and NSTEMI for all intents and purposes, share similar pathophysiology, but at increasing severity. This article focuses on the diagnosis, risk stratification, management, and strategies that impact outcomes in NSTEMI.

Novel aspects of antiplatelet therapy in cardiovascular disease

Antiplatelet therapy is a cornerstone in the secondary prophylaxis of adverse cardiovascular events such as myocardial infarction and stroke. The cyclooxygenase inhibitor aspirin remains the most frequently prescribed antiplatelet drug, followed by adenosine diphosphate P2Y12 receptor blockers. Glycoprotein IIb-IIIa antagonists are intravenously available antiplatelet agents preventing platelet-to-platelet aggregation via the fibrinogen receptor. The thrombin receptor inhibitor vorapaxar allows the targeting of yet a third pathway of platelet activation. Despite the advent of novel agents and major advances in antiplatelet treatment over the last decade, atherothrombotic events still impair the prognosis of many patients with cardiovascular disease. Consequently, antiplatelet therapy remains a field of intense research and a large number of studies on its various aspects are published each year. This review article summarizes recent developments in antiplatelet therapy in cardiovascular disease focusing particularly on the duration of dual antiplatelet therapy, new treatment regimens, the role of platelet function testing, and potential future targets of antiplatelet agents.