A randomized comparison of high clopidogrel loading doses in patients with non-ST-segment elevation acute coronary syndromes: the ALBION (Assessment of the Best Loading Dose of Clopidogrel to Blunt Platelet Activation, Inflammation and Ongoing Necrosis) trial

Ticagrelor vs Clopidogrel in Clopidogrel-Naive Patients With Chronic Coronary Syndrome

BACKGROUND

Whether ticagrelor may reduce periprocedural myocardial necrosis after elective percutaneous coronary intervention (PCI) in patients with and without chronic clopidogrel therapy is unclear.

OBJECTIVES

This study sought to compare ticagrelor vs clopidogrel in patients with and without chronic clopidogrel therapy before undergoing elective PCI.

METHODS

In this prespecified analysis of the ALPHEUS (Assessment of Loading With the P2Y12 Inhibitor Ticagrelor or Clopidogrel to Halt Ischemic Events in Patients Undergoing Elective Coronary Stenting) trial, patients were defined as clopidogrel(+) and clopidogrel(-) according to the presence and absence of clopidogrel treatment for ≥7 days before PCI, respectively. The primary endpoint was the composite of PCI-related myocardial infarction and major injury as defined by the third and fourth universal definition 48 hours after PCI.

RESULTS

A total of 1,882 patients were included, 805 (42.7%) of whom were clopidogrel(+). These patients were older, had more comorbidities, and had more frequent features of complex PCI. The primary endpoint was less frequently present in clopidogrel(-) compared to clopidogrel(+) patients (32.8% vs 40.0%; OR: 0.73; 95% CI: 0.60-0.88), but no significant differences were reported for the risk of death, myocardial infarction, stroke, or transient ischemic attack at 48 hours or 30 days. Ticagrelor did not reduce periprocedural myocardial necrosis or the risk of adverse outcomes, and there was no significant interaction regarding the presence of chronic clopidogrel treatment.

CONCLUSIONS

Clopidogrel-naive patients presented less periprocedural complications compared to clopidogrel(+) patients, a difference related to a lower risk profile and less complex PCI. The absence of clopidogrel at baseline did not affect the absence of a difference between ticagrelor and clopidogrel in terms of PCI-related complications supporting the use of clopidogrel as the standard of care in elective PCI in patients with or without chronic clopidogrel treatment.

Racial differences in P2Y12 inhibitor responsiveness in patients undergoing neuro-endovascular procedures: A cohort from the Middle East

BACKGROUND

Data on P2Y12 inhibitors responsiveness from the middle east is scarce. We sought to investigate patient responsiveness to P2Y12 inhibitors within a cohort of major races that characterize the UAE population. The secondary objective was to assess risk factors for hyper and hypo-responsiveness in this population.

METHODS

We conducted a cross-sectional study on adults who received either clopidogrel or ticagrelor treatments and had platelet responsiveness testing before undergoing neuro-endovascular interventions at our quaternary care hospital between March 2015 and April 2019.

RESULTS

During the study period, 249 subjects met the inclusion criteria. Overall, 17.3 % were hyper-responsive and 25.7 % were hypo-responsive to P2Y12 inhibitors. When comparing between the P2Y12 inhibitors, rates of hyper-responsiveness were significantly higher to ticagrelor when compared to clopidogrel (11 versus 6 %, p = 0.02 respectively). Contrarily, hypo-responsiveness rates were significantly higher in clopidogrel treated patients compared to their ticagrelor treated counterparts (23 versus 2 %, p < .001 respectively). Patients of Middle-Eastern origin showed a significantly higher rate of hypo-responsiveness to both clopidogrel and ticagrelor when compared to other races (41.1 % and 26.7 %, P < 0.001 respectively). Asians showed the highest rates of hyper-responsiveness for both agents. Multivariate logistic regression analysis showed that proton pump inhibitors and statin combination, (OR: 6.39, 95 %CI [1.60, 25.392]), and Middle East vs. Indian subcontinent patients (OR: 4.67, 95 %CI [1.79-12.14]) were independent predictors of hypo-responsiveness to both P2Y12 inhibitors.

CONCLUSION

This study demonstrated a high rate of hypo-responsiveness to P2Y12 inhibitors in a UAE cohort of patients undergoing neuro-endovascular procedures. In addition, therapeutic responsiveness to P2Y12 inhibitors varied markedly based on the racial background. Future larger studies are needed to evaluate genetic variations that may contribute to this rate of hypo-responsiveness in our population.

P2Y12 Inhibitor Loading Time Before Elective PCI and the Prevention of Myocardial Necrosis

BACKGROUND

There are dated and conflicting data about the optimal timing of initiation of P2Y12 inhibitors in elective percutaneous coronary intervention (PCI). Peri-PCI myocardial necrosis is associated with poor outcomes. We aimed to assess the impact of the P2Y12 inhibitor loading time on periprocedural myocardial necrosis in the population of the randomized Assessment of Loading With the P2Y12 Inhibitor Ticagrelor or Clopidogrel to Halt Ischemic Events in Patients Undergoing Elective Coronary Stenting (ALPHEUS) trial, which compared ticagrelor with clopidogrel in high-risk patients who received elective PCI.

METHODS

The ALPHEUS trial divided 1809 patients into quartiles of loading time. The ALPHEUS primary outcome was used (type 4 [a or b] myocardial infarction or major myocardial injury) as well as the main secondary outcome (type 4 [a or b] myocardial infarction or any type of myocardial injury).

RESULTS

Patients in the first quartile group (Q1) presented higher rates of the primary outcome (P = 0.01). When compared with Q1, incidences of the primary outcome decreased in patients with longer loading times (adjusted odds ratio [adjOR], 0.70 [0.52.-0.95]; P = 0.02 for Q2; adjOR 0.65 [0.48-0.88]; P < 0.01 for Q3; adjOR 0.66 [0.49-0.89]; P < 0.01 for Q4). Concordant results were found for the main secondary outcome. There was no interaction with the study drug allocated by randomization (clopidogrel or ticagrelor). Bleeding complications (any bleeding ranging between 4.9% and 7.3% and only 1 major bleeding at 48 hours) and clinical ischemic events were rare and did not differ among groups.

CONCLUSIONS

In elective PCI, administration of the oral P2Y12 inhibitor at the time of PCI could be associated with more frequent periprocedural myocardial necrosis than an earlier administration. The long-term clinical consequences remain unknown.

A Systematic Review of Clopidogrel Resistance in Vascular Surgery: Current Perspectives and Future Directions

BACKGROUND

Clopidogrel resistance is a well-described phenomenon that has been linked to adverse cardiovascular events in patients with coronary artery disease. The impact of clopidogrel resistance in patient outcomes after vascular and endovascular surgery is not well-established.

METHODS

Using preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, a literature review with the medical subject headings (MeSH) terms "(clopidogrel resistance) and (vascular)", "(clopidogrel resistance) and (vascular surgery)", "(clopidogrel resistance) and (endovascular)", and "(clopidogrel resistance) and (endovascular surgery)" was performed in PubMed and Cochrane databases, to identify all peer-reviewed studies performed on clopidogrel resistance in vascular and endovascular surgery. Studies written in the English language from inception to 2022 were included. Case reports, studies with limited information, nonhuman studies, and studies not pertaining to vascular or endovascular surgery were excluded from analysis. Each study was independently reviewed by 2 qualified researchers to assess eligibility.

RESULTS

Of the 691 studies identified through the MeSH strategy, 16 studies met the inclusion criteria and were reviewed and summarized. These studies focused on extracranial cerebrovascular disease (n = 5) and peripheral arterial disease (PAD, n = 11), encompassing a total of 1,716 patients. The prevalence of clopidogrel resistance ranged from 0% to 83.3%, depending on the diagnostic assay and cutoff values used. In cerebrovascular disease, clopidogrel resistance may be associated with cerebral embolization, ischemic neurologic events, and vascular-related mortality. In PAD, clopidogrel resistance has been linked to recurrent stent thrombosis, target lesion revascularization, amputation-free survival, and all-cause mortality.

CONCLUSIONS

This systematic review provides an up-to-date summary of clopidogrel resistance in vascular and endovascular surgery. The impact of clopidogrel resistance remains incompletely investigated, and future studies are needed to clarify the role of resistance testing in patients with vascular disease.

Clopidogrel resistance is common in patients undergoing vascular and coronary interventions

OBJECTIVES

"Clopidogrel resistance," also defined as heightened platelet reactivity (HPR) while on clopidogrel therapy, may lead to a sub-optimal antiplatelet effect and a potential thrombotic event. There is limited literature addressing the prevalence of HPR in a large cohort of patients receiving either coronary or endovascular interventions.

METHODS

In a large integrated healthcare system, patients with a P2Y12 reaction units (PRU) test were identified. HPR was defined as a PRU ≥ 200 during clopidogrel therapy. Vascular and coronary interventions were identified utilizing CPT codes, HPR prevalence was calculated, and Fischer's exact test was used to determine significance.

RESULTS

From an initial cohort of 2,405,957 patients (October 2014 to January 2020), we identified 3301 patients with PRU tests administered. Of these, 1789 tests had a PRU ≥ 200 (HPR overall prevalence, 54%). We then identified 1195 patients who underwent either an endovascular or coronary procedure and had a PRU measurement. This corresponded to 935 coronary and 260 endovascular interventions. In the coronary cohort, the HPR prevalence was 54% (503/935). In the vascular cohort, the HPR prevalence was 53% (137/260); there was no difference between cohorts in HPR prevalence (p = 0.78).

CONCLUSION

"Clopidogrel resistance" or HPR was found to be present in nearly half of patients with cardiovascular disease undergoing intervention. Our data suggest HPR is more common in the cardiovascular patient population than previously appreciated. Evaluating patients for HPR is both inexpensive ($25) and rapid (< 10 min). Future randomized studies are warranted to determine whether HPR has a clinically detectable effect on revascularization outcomes.

[Acute coronary syndrome in the prehospital phase and in the emergency department]

Acute coronary syndrome is the most common reason for the deployment of emergency medical services in Germany. Approximately 20-25% of all medical emergencies result from the indications for the suspicion of acute coronary syndrome. A substantial proportion of the total mortality rate is observed in the preclinical phase. Consequently, targeted diagnostics and treatment are of particular importance in this early phase. This article provides recommendations for the approach to patients with acute coronary syndrome in the prehospital phase and in the emergency department.

Clopidogrel Bolus is Inferior to Sustained Clopidogrel Pretreatment in Patients Undergoing Carotid Artery Stent Placement

BACKGROUND

Clopidogrel bolus is an option used before carotid artery stent (CAS) placement when sustained clopidogrel pretreatment is not used.

OBJECTIVE

To compare the effect of clopidogrel bolus (450 mg administered ≥4 hours) with sustained clopidogrel pretreatment (48 hours or greater) before CAS among patients recruited in the Carotid Revascularization Endarterectomy versus Stenting Trial.

METHODS

We compared the rates of primary end point (either any stroke, myocardial infarction, or death during the periprocedural period or any ipsilateral stroke within 4 years) between patients who received clopidogrel bolus and those who received sustained clopidogrel pretreatment using Cox proportional hazards analysis after adjusting for age, sex, symptomatic status, and initial severity of stenosis (≥70% vs <70%) over 4 years.

RESULTS

The rate of periprocedural stroke (7.3% vs 3.4%, P = .03) and primary end point (11.3% vs 5.9%, P = .02) was significantly higher among patients who received clopidogrel bolus. The risk of primary end point was significantly higher in patients who received clopidogrel bolus (hazards ratio 1.9, 95% CI 1.1-3.4, P = .02) after adjusting for potential confounders. The overall mean (±standard deviation) primary end point-free survival based on Kaplan-Meier analysis was 7.0 ± 0.2 years for patients who received clopidogrel bolus and 8.9 ± 0.1 years for those who received sustained clopidogrel pretreatment (log-rank test P = .011).

CONCLUSION

Clopidogrel bolus was associated with higher rates of adverse outcomes compared with sustained clopidogrel pretreatment in patients who underwent CAS. Therefore, clopidogrel bolus may not be equivalent to sustained clopidogrel pretreatment.

P2Y12 inhibition in acute coronary syndromes treated with percutaneous intervention - Understanding the debate on Prasugrel or Ticagrelor

After more than 10 years of routine clinical use, a debate about the preference of prasugrel over ticagrelor has been unveiled following publication of the ISAR-REACT 5 trial, an investigator-initiated trial directly comparing both substances as part of dual anti-platelet therapy following interventional treatment in patients with acute coronary syndromes (ACS). Both substances had been tested in trials, approved by authorities and subsequently recommended by guidelines according to the strategy applied in the respective approval trial. This resulted in prasugrel tested in TRITON only be given after diagnostic coronary angiography in the absence of ST-segment elevations (NSTE-ACS) and ticagrelor tested in PLATO being administered even before diagnostic coronary angiography in all forms of acute coronary syndromes. Whichever way was safest and most efficient, had never been clarified before. ISAR-REACT 5 showed superior efficacy of prasugrel over ticagrelor in general, and of deferred administration of prasugrel over pre-treatment with ticagrelor in NSTE-ACS patients undergoing percutaneous coronary interventions. Subsequently, in 2020 the European guidelines for NSTE-ACS adopted both positions in recommending the respective preference. Afterwards, a confrontational debate erupted between those favouring the ISAR-REACT 5 results and their implementation in guidelines and others still preferring the generalized interpretation of the overall study results from PLATO. In this review, we reflect the history leading to trial design of TRITON and PLATO and the way this subsequently impacted on clinical practice and guideline recommendations.

Evaluation of a Clinically Relevant Drug-Drug Interaction Between Rosuvastatin and Clopidogrel and the Risk of Hepatotoxicity

Purpose: The combination therapy of rosuvastatin (RSV) and the platelet inhibitor clopidogrel (CP) is widely accepted in the management of cardiovascular diseases. The objective of the present study was to identify the mechanism of RSV–CP DDI and evaluate the risk of hepatotoxicity associated with the concomitant use of CP.

Methods: We first studied the effect of CP and its major circulating metabolite, carboxylic acid metabolite (CPC), on RSV transport by overexpressing cells and membrane vesicles. Second, we investigated whether a rat model could replicate this DDI and then be used to conduct mechanistic studies and assess the risk of hepatotoxicity. Then, cytotoxicity assay in hepatocytes, biochemical examination, and histopathology were performed to measure the magnitude of liver injury in the presence and absence of DDI.

Results: CP inhibited OATP1B1-mediated transport of RSV with an IC₅₀ value of 27.39 μM. CP and CPC inhibited BCRP-mediated RSV transport with IC₅₀ values of <0.001 and 5.96 μM, respectively. The CP cocktail (0.001 μM CP plus 2 μM CPC) significantly inhibited BCRP-mediated transport of RSV by 26.28%. Multiple p.o. doses of CP significantly increased intravenous RSV plasma AUC_0-infinity by 76.29% and decreased intravenous RSV CL by 42.62%. Similarly, multiple p.o. doses of CP significantly increased p.o. RSV plasma AUC_0-infinity by 87.48% and decreased p.o. RSV CL by 43.27%. CP had no effect on cell viability, while RSV exhibited dose-dependent cytotoxicity after 96 h incubation. Co-incubation of 100 μM CP and RSV for 96 h significantly increased intracellular concentrations and cell-to-medium concentration ratios of RSV and reduced hepatocyte viability. Histological evaluation of liver specimens showed patterns of drug-induced liver injury. Cholestasis was found in rats in the presence of DDI.

Conclusion: CP is not a clinically relevant inhibitor for OATP1B1 and OATP1B3. The primary mechanism of RSV–CP DDI can be attributed to the inhibition of intestinal BCRP by CP combined with the inhibition of hepatic BCRP by CPC. The latter is likely to be more clinically relevant and be a contributing factor for increased hepatotoxicity in the presence of DDI.

Residual platelet reactivity, thrombus burden and myocardial reperfusion in patients treated by PCI after successful pre-hospital fibrinolysis compared to primary PCI

We compared residual platelet reactivity and post PCI atherothrombotic burden using OFDI in patients successfully treated by primary PCI versus pharmacoinvasive approach (PI) defined as PCI after successful pre-hospital fibrinolysis. Despite pre-hospital P2Y12-inhibitor loading dose, high rates of high on-treatment platelet reactivity were found at the time of PCI in both groups. Primary PCI patients had higher post stenting thrombus burden and lower rates of final normal myocardial blush grade compared to PI. These findings support the use of a pharmacoinvasive reperfusion strategy especially when primary PCI cannot be timely performed.

Is platelet function testing at the acute phase under P2Y12 inhibitors helpful in predicting bleeding in real-life patients with acute coronary syndrome? The AVALANCHE study

BACKGROUND

In patients with acute coronary syndrome (ACS), current international guidelines recommend newer potent and predictable P2Y₁₂ inhibitors as first-line treatment despite a greater bleeding risk compared with clopidogrel.

AIM

To determine if platelet function testing can predict bleeding in real-life patients with ACS treated with newer P2Y₁₂ inhibitors.

METHODS

In this retrospective study, all consecutive adults admitted to the Lariboisière University Hospital for ACS, whatever the P2Y₁₂ inhibitor prescribed, who had platelet function testing (vasodilator-stimulated phosphoprotein phosphorylation [VASP] index and aggregation tests) during the initial hospital stay were included. Follow-up was performed to record bleeding events according to the Bleeding Academic Research Consortium (BARC) classification.

RESULTS

A total of 364 patients were included, treated with ticagrelor (n=123), prasugrel (n=105) or clopidogrel (n=136); 42.3% after an ST-segment elevation myocardial infarction, 27.1% after a non-ST-segment elevation myocardial infarction and 30.6% with unstable angina. Mean age was 64±11 years. Median VASP index was significantly lower with the newer P2Y₁₂ inhibitors (14% under ticagrelor, 14% under prasugrel) than with clopidogrel (42%). Despite these differences in the degree of platelet inhibition, the occurrence of bleeding (BARC 2-5) during follow-up was 7.7% overall, and was similar for all P2Y₁₂ inhibitors (ticagrelor 8.9%; prasugrel 6.6%; clopidogrel 7.4%). For each P2Y₁₂ inhibitor, it was impossible to determine a VASP index threshold under which bleeding was significantly greater during follow-up. Similarly, ADP-induced aggregation was more profoundly inhibited by ticagrelor and prasugrel than by clopidogrel, but this did not allow a threshold to be set for increased haemorrhagic risk.

CONCLUSIONS

Despite the substantial occurrence of bleeding in patients with ACS during follow-up, neither the VASP index nor platelet aggregation test results measured at the acute phase were helpful in predicting bleeding risk. Whether platelet function testing could be helpful later in the course of treatment remains to be evaluated.

Tackling the gap in platelet inhibition with oral antiplatelet agents in high-risk patients undergoing percutaneous coronary intervention

Introduction: Oral P2Y₁₂ inhibitors represent the mainstay therapy for the prevention of thrombotic complications in patients presenting with an acute coronary syndrome and/or undergoing percutaneous coronary intervention (PCI). However, the onset of antiplatelet action of the oral P2Y₁₂ inhibitors is affected by their need to be absorbed in the gastrointestinal (GI) tract before becoming systemically available.Areas covered: Following oral intake of P2Y₁₂ inhibitors, the timeframe required for GI absorption leads to a window of inadequate antiplatelet protection during which patients are at increased thrombotic risk. The onset of action of the oral P2Y₁₂ inhibitors is even further delayed in high-risk patients, underscoring the need to define strategies to bridge the gap in platelet inhibitory effects following their intake.Expert opinion: Multiple mechanisms may impair GI absorption leading to a delay in the onset of action of oral P2Y₁₂ inhibitors. Several strategies have been tested to overcome the gap in platelet inhibition in high-risk patients undergoing PCI. These include administration of crushed or chewed tablets to improve the dissolution rate and use of opioid receptor antagonists or metoclopramide to counteract impairment of gastric motility induced by opioids. However, intravenous antiplatelet therapies represent the most effective strategy to bridge such gap in platelet inhibition.

The Role of Genetic Polymorphism and Other Factors on Clopidogrel Resistance (CR) in an Asian Population with Coronary Heart Disease (CHD)

Clopidogrel is a widely-used antiplatelet drug. It is important for the treatment and prevention of coronary heart disease. Clopidogrel can effectively reduce platelet activity and therefore reduce stent thrombosis. However, some patients still have ischemic events despite taking the clopidogrel due to the alteration in clopidogrel metabolism attributable to various genetic and non-genetic factors. This review aims to summarise the mechanisms and causes of clopidogrel resistance (CR) and potential strategies to overcome it. This review summarised the possible effects of genetic polymorphism on CR among the Asian population, especially CYP2C19 *2 / *3 / *17, where the prevalence rate among Asians was 23.00%, 4.61%, 15.18%, respectively. The review also studied the effects of other factors and appropriate strategies used to overcome CR. Generally, CR among the Asian population was estimated at 17.2-81.6%. Therefore, our overview provides valuable insight into the causes of RC. In conclusion, understanding the prevalence of drug metabolism-related genetic polymorphism, especially CYP2C19 alleles, will enhance clinical understanding of racial differences in drug reactions, contributing to the development of personalised medicine in Asia.

Infarct size following loading with Ticagrelor/Prasugrel versus Clopidogrel in ST-segment elevation myocardial infarction

BACKGROUND

Treatment with newer direct-acting anti-platelet drugs (Ticagrelor and Prasugrel) prior to primary percutaneous coronary intervention (PCI) is associated with improved outcome in patients with ST-segment elevation myocardial infarction (STEMI) when compared with Clopidogrel. We compared infarct size following treatment with Ticagrelor/Prasugrel versus Clopidogrel in the DANish trial in Acute Myocardial Infarction (DANAMI-3) population of STEMI patients treated with primary PCI.

METHODS AND RESULTS

Patients were loaded with Clopidogrel, Ticagrelor or Prasugrel in the ambulance before primary PCI. Infarct size and myocardial salvage index were calculated using cardiac magnetic resonance (CMR) during index admission and at three-month follow-up. Six-hundred-and-ninety-three patients were included in this analysis. Clopidogrel was given to 351 patients and Ticagrelor/Prasugrel to 342 patients. The groups were generally comparable in terms of baseline and procedural characteristics. Median infarct size at three-month follow-up was 12.9% vs 10.0%, in patients treated with Clopidogrel and Ticagrelor/ Prasugrel respectively (p < 0.001), and myocardial salvage index was 66% vs 71% (p < 0.001). Results remained significant in a multiple regression model (p < 0.001).

CONCLUSIONS

Pre-hospital loading with Ticagrelor or Prasugrel compared to Clopidogrel, was associated with smaller infarct size and larger myocardial salvage index at three-month follow-up in patients with STEMI treated with primary PCI.

Meta-analysis Comparing Outcomes of Type 2 Myocardial Infarction and Type 1 Myocardial Infarction With a Focus on Dual Antiplatelet Therapy

BACKGROUND

There are important knowledge gaps in type 2 myocardial infarction (T2MI). Our primary objective was to compare the outcomes of patients with T2MI with those of patients with type 1 myocardial infarction (T1MI). Our secondary objective was to determine whether randomized controlled trials (RCTs) evaluating dual antiplatelets (DAPTs) have explicitly included patients with T2MI.

METHODS

We performed a meta-analysis comparing outcomes of patients with T2MI with patients with T1MI and a separate systematic review to evaluate the inclusion of T2MI in RCTs evaluating DAPT. There were 19 cohorts enrolling 48,829 patients (40,604 with T1MI and 5361 with T2MI) and 51 RCTs enrolling 188,132 patients with acute coronary syndrome.

RESULTS

Patients with T2MI had approximately 2-fold increases in unadjusted odds of long-term mortality compared with patients with T1MI (odds ratio, 2.47; 95% confidence interval, 2.06-2.96; P < 0.0001) and a 45% increase in adjusted odds of long-term mortality (odds ratio, 1.45; 95% confidence interval, 1.25-1.69; P < 0.0001, respectively). There was no published evaluation of efficacy, effectiveness, and safety of DAPT in patients with T2MI.

CONCLUSION

Patients with T2MI are at increased risk of adjusted all-cause long-term mortality compared with patients with T1MI. The role of DAPT remains unclear in T2MI.

Cangrelor in clinical use

Inadequate antiplatelet effects can result in substantial morbidity and mortality in patients with acute coronary syndrome and percutaneous coronary intervention (PCI). Cangrelor is a rapid onset and potent intravenous P2Y12 inhibitor that has been shown in large randomized controlled trials to reduce periprocedural complications for PCI compared with clopidogrel, the most commonly used P2Y12 inhibitor. Cangrelor should be considered in the setting of PCI to reduce the risk of periprocedural complications such as myocardial infarction, repeat coronary revascularization and stent thrombosis in patients not yet treated with another P2Y12 inhibitor or glycoprotein IIb/IIIa inhibitor. In this review, the importance of adequate P2Y12 inhibition, cangrelor's pharmacology and clinical profiles, and future directions for the cangrelor are discussed.

What Are Optimal P2Y12 Inhibitor and Schedule of Administration in Patients With Acute Coronary Syndrome?

Guidelines recommend treatment with a P2Y12 platelet adenosine diphosphate receptor inhibitor in patients undergoing elective or urgent percutaneous coronary intervention (PCI), but the optimal agent or timing of administration is still not clearly specified. The P2Y12 inhibitor was initially used for its platelet anti-aggregatory action to block thrombosis of the recanalized coronary artery or deployed stent. It is now recognized that these agents also offer potent cardioprotection against a reperfusion injury that occurs in the first minutes of reperfusion if platelet aggregation is blocked at the time of reperfusion. But this is difficult to achieve with oral agents which are slowly absorbed and often require time-consuming metabolic activation. Patients with ST-segment elevation myocardial infarction who usually have a large mass of myocardium at risk of infarction seldom have sufficient time for upstream-administered oral agents to achieve a therapeutic P2Y12 level of inhibition by the time of balloon inflation. However, optimal treatment could be assured by initiating an IV cangrelor infusion shortly prior to stenting followed by subsequent post-PCI transition to an oral agent, that is, ticagrelor, once success of the recanalization and absence of need for surgical intervention are confirmed. Not only should this sequence provide optimal protection against infarction, it should also negate bleeding if coronary artery bypass grafting should be required since stopping the cangrelor infusion at any time will quickly restore platelet reactivity. It is anticipated that cangrelor-induced myocardial salvage will help preserve myocardial function and significantly diminish postinfarction heart failure.

Pharmacokinetics and competitive pharmacodynamics of ADP-induced platelet activation after oral administration of clopidogrel to horses

OBJECTIVE

To determine pharmacokinetics and pharmacodynamics after oral administration of a single dose of clopidogrel to horses.

ANIMALS

6 healthy adult horses.

PROCEDURES

Blood samples were collected before and at various times up to 24 hours after oral administration of clopidogrel (2 mg/kg). Reactivity of platelets from each blood sample was determined by optical aggregometry and phosphorylation of vasodilator-stimulated phosphoprotein (VASP). Concentrations of clopidogrel and the clopidogrel active metabolite derivative (CAMD) were measured in each blood sample by use of liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were determined with a noncompartmental model.

RESULTS

Compared with results for preadministration samples, platelet aggregation in response to 12.5μM ADP decreased significantly within 4 hours after clopidogrel administration for 5 of 6 horses. After 24 hours, platelet aggregation was identical to that measured before administration. Platelet aggregation in response to 25μM ADP was identical between samples obtained before and after administration. Phosphorylation of VASP in response to ADP (20μM) and prostaglandin E₁ (3.3μM) was also unchanged by administration of clopidogrel. Time to maximum concentration of clopidogrel and CAMD was 0.54 and 0.71 hours, respectively, and calculated terminal-phase half-life of clopidogrel and CAMD was 1.81 and 0.97 hours, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Clopidogrel or CAMD caused competitive inhibition of ADP-induced platelet aggregation during the first 24 hours after clopidogrel administration. Because CAMD was rapidly eliminated from horses, clopidogrel administration may be needed more frequently than in other species in which clopidogrel causes irreversible platelet inhibition. (Am J Vet Res 2019;80:505-512).

Is ticagrelor worth its high cost and side-effects?

Ticagrelor is a reversible P2Y₁₂ receptor antagonist that is more potent than clopidogrel. When used in combination with aspirin, it reduces cardiovascular events in patients with acute coronary syndrome. However, unbiased review of 5 randomised controlled trials indicates that although statistically significant, the clinical superiority of ticagrelor over clopidogrel is modest. Thus, identification of patients who benefit the most from ticagrelor is a priority. Besides bleeding issues, ticagrelor can frequently cause bouts of dyspnoea, which requires ticagrelor replacement by another P2Y₁₂ receptor antagonist, with a loading dose.

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.

Clinical safety profile of ticagrelor compared to clopidogrel in 1208 patients: Real world evidence

Introduction

Dual antiplatelet treatment is recommended by current clinical practice guidelines for patients undergoing PCI. The PLATO trial showed superiority of ticagrelor to clopidogrel in reducing the rate of death from vascular causes, myocardial infarction and stroke without increase in the rate of overall major bleeding in ACS patients. However, real world evidence in Indian patients is limited. The objective of this study is to compare safety profile of ticagrelor with clopidogrel in real world settings.

Methodology

In this single centered retrospective observational study, a total of 1208 serial patient records undergoing PCI (ACS and stable angina patients as well) treated with Ticagrelor or Clopidogrel were collected and analyzed to look into in hospital outcomes. We excluded the patient’s data that were incomplete.

Results

In total of 1208 patients, 604 patients received ticagrelor and similarly 604 patient received clopidogrel. No significant differences in the rates of major life threatening bleeding and any major bleeding were observed between ticagrelor and clopidogrel group (0.2% (n = 1) vs. 0.7% (n = 4), p = 0.18 and 2.8% (n = 17) vs. 3% (n = 18), p = 0.86 respectively). There was increase in minor bleeding rate with ticagrelor compared to clopidogrel (21.4% & 13.6%, p = 0.00).

Conclusion

In the real world settings, patients undergoing PCI treated with ticagrelor showed similar safety profile compared to clopidogrel but with increase in minor bleeding rate. The observed results were in alignment with PLATO clinical trial.

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.

Switching From Ticagrelor or Prasugrel to Clopidogrel

Ticagrelor and prasugrel are newer antiplatelet drugs which, like clopidogrel, block the P2Y12 platelet receptor to inhibit platelet aggregation. Compared with clopidogrel, both ticagrelor and prasugrel have greater clinical efficacy but also have a higher risk of bleeding and are much more costly. Therefore, some institutions and providers switch patients from ticagrelor or prasugrel to clopidogrel in an effort to lower bleeding risk, stem costs, or otherwise ensure that patients can safely adhere to long-term P2Y12 inhibitor therapy. From a pharmacodynamic perspective, switching patients from ticagrelor or prasugrel to clopidogrel comes at a cost of less antiplatelet efficacy. However, it is unclear if antiplatelet efficacy is diminished enough to affect clinical outcomes. This is because clinical trial data investigating such a switch is scant, leaving the clinician unsure as to the acceptability of this practice. Current clinical trial data have thus far not shown any clinical detriment from switching from ticagrelor or prasugrel to clopidogrel, but there are many limitations to these investigations. So although a large-scale switch of patients from ticagrelor or prasugrel to clopidogrel is not recommended, if the patient is unable to adhere to long-term ticagrelor or prasugrel therapy, switching him/her to clopidogrel seems to be a reasonable practice to maintain chronic suppression of platelet aggregation and minimize the risk of ischemic events.

Association between baseline platelet count and severe adverse outcomes following percutaneous coronary intervention

Objective

The aim is to evaluate the association between baseline platelet count (PC) and severe adverse outcomes following percutaneous coronary intervention (PCI) in current real-world practice.

Methods

A total of 18,788 patients underwent PCI with drug-eluting stents constituted the study population. Patients were categorized as having low (< 150 × 1000/µL), normal (150–300 × 1000/µL), and high (≥ 300 × 1000/µL) baseline PC. The primary endpoints included in-hospital and follow-up all-cause mortality. The secondary endpoint was major bleeding requiring a blood transfusion.

Results

In-hospital mortality rates for patients with low, normal, and high baseline PC were 0.6%, 0.4%, and 0.4%, respectively (P = 0.259). Similarly, mortality rates during long-term follow-up (median 23.8 months) for patients with low, normal, and high baseline PC were 0.9%, 0.6%, and 0.7%, respectively (P = 0.079). After multivariate adjustment, patients with low or high baseline PC tended to have similar risks for both in-hospital and follow-up mortality compared with the normal group. Subgroup analyses failed to demonstrate an independent prognostic value of baseline PC in specific population groups except patients who undwent transfemoral PCI. There was also no significant difference in the incidence of major bleeding requiring a blood transfusion in the low, normal, and high groups (0.5%, 0.3%, and 0.3%, respectively; P = 0.320). After multivariate adjustment, low or high baseline PC did not significantly increase the risk of major bleeding.

Conclusion

There is no significant association between baseline PC and severe adverse outcomes following PCI in current real-world practice.

Potent effect of prasugrel on acute phase resolution of intra-stent athero-thrombotic burden after percutaneous intervention to acute coronary syndrome

BACKGROUND

Recent studies suggested protruding thrombus and atheroma after stent placement could be a substrate for subsequent adverse ischemic events. Although protruded atherothrombotic burden can be assessed as intra-stent tissue (IST) by optical coherence tomography (OCT), the effects of potent antiplatelet therapy on the acute phase resolution of IST in patients with acute coronary syndrome (ACS) was unknown.

METHODS

Ninety-six consecutive ACS patients with multi-vessel disease were enrolled in this prospective registry. In combination with aspirin, either clopidogrel or prasugrel was selected according to the date of enrolment. OCT examination was done immediately after percutaneous coronary intervention (post-PCI) and 10 days after index PCI (follow-up acute phase) to calculate averaged IST score as semi-quantitative measures of IST. High residual platelet reactivity (HRPR) was defined as platelet reactivity units (PRU)≥240 by VerifyNow P2Y12 assay (Accumetrics Inc., San Diego, CA, USA).

RESULTS

Thirty two patients (38 stents) were enrolled in the prasugrel group and sixty four patients (72 stents) in the clopidogrel group. Averaged IST scores post-PCI were similar between the two groups (0.68±0.41 vs. 0.68±0.40, p=0.99), which decreased in all of the prasugrel group and in 87.5% of the clopidogrel group (p=0.02). Consequently, changes in averaged IST score (delta averaged IST score) were significantly greater in the prasugrel group compared to those in the clopidogrel group (-0.411±0.288 vs. -0.299±0.270, p=0.045). The frequency of HRPR was significantly lower in the prasugrel group (10.0% vs 32.4%, p=0.028).

CONCLUSIONS

Prasugrel plus aspirin achieved greater acute phase reduction of IST than clopidogrel plus aspirin, which might underlie the clinical benefit of potent antiplatelet therapy in ACS. (UMIN000018751).

P2Y12 receptor inhibitors: an evolution in drug design to prevent arterial thrombosis

INTRODUCTION

P2Y12 inhibitors are a critical component of dual antiplatelet therapy (DAPT), which is the superior strategy to prevent arterialthrombosis in patients with acute coronary syndromes (ACS) and undergoing stent implantation.. Areas covered: Basic science articles, clinical studies, and reviews from 1992-2017 were searched using Pubmed library to collet impactful literature. After an introduction to the purinergic receptor biology, this review summarizes current knowledge on P2Y12 receptor inhibitors. Furthermore, we describe the subsequent improvements of next-generation P2Y12 receptor inhibitors facing the ambivalent problem of bleeding events versus prevention of arterial thrombosis in a variety of clinical settings. Therefore, we summarize data from relevant preclinical and clinical trials of currently approved P2Y12 receptor inhibitors (clopidogrel, prasugrel, ticagrelor, cangrelor) and provide strategies of drug switching and management of bleeding events. Expert opinion: An enormous amount of pharmacologic and clinical data is available for the application of P2Y12 receptor inhibitors. Today prasugrel, ticagrelor and clopidogrel are the standard of care drugs during dual antiplatelet therapy for ACS patients, but have considerable rates of bleeding. Recent and future clinical trials will provide evidence for subsequent escalation and de-escalation strategies of P2Y12 receptor inhibition. These data may pave the way for an evidence-based, individualized P2Y12 receptor inhibitor therapy.

High-sensitive C-reactive protein and dual antiplatelet in intracranial arterial stenosis

Objective

To determine the relationship of high-sensitive C-reactive protein (hsCRP) and the efficacy and safety of dual antiplatelet therapy in patients with and without intracranial arterial stenosis (ICAS) in the Clopidogrel in High-Risk Patients with Acute Non-disabling Cerebrovascular Events (CHANCE) trial.

Methods

A subgroup of 807 patients with both magnetic resonance angiography images and hsCRP measurement was analyzed. Cox proportional hazards models were used to assess the interaction of hsCRP levels with the effects of dual and single antiplatelet therapy.

Results

A total of 358 (44.4%) patients had ICAS and 449 (55.6%) did not. The proportion of patients with elevated hsCRP levels was higher in the ICAS group than in the non-ICAS group (40.2% vs 30.1%, p = 0.003). There was significant interaction between hsCRP and the 2 antiplatelet therapy groups in their effects on recurrent stroke after adjustment for confounding factors in the patients with ICAS (p = 0.012), but not in those without (p = 0.256). Compared with aspirin alone, clopidogrel plus aspirin significantly reduced the risk of recurrent stroke only in the patients with ICAS and nonelevated hsCRP levels (adjusted hazard ratio 0.27; 95% confidence interval 0.11 to 0.69; p = 0.006). Similar results were observed for composite vascular events. No significant difference in bleeding was found.

Conclusions

Presence of both ICAS and nonelevated hsCRP levels may predict better response to dual antiplatelet therapy in reducing new stroke and composite vascular events in minor stroke or high-risk TIA patients. Further large-scale randomized and controlled clinical trials are needed to confirm this finding.

Identification of poor response to P2Y12 inhibitors in ACS patients with a new ELISA-based vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation assay

A new ELISA technique has been developed to measure the vasodilator-associated stimulated phosphoprotein (VASP) platelet reactivity index (PRI) in clopidogrel-treated patients. This technique has not been evaluated in acute coronary syndrome (ACS) patients or in prasugrel-treated patients. We assessed the accuracy of ELISA-VASP to identify high on-treatment platelet reactivity (HPR) in ACS patients in comparison with established platelet function tests. Platelet reactivity was measured in 240 ACS patients treated with clopidogrel (75 or 150 mg) or prasugrel (5 or 10 mg) using flow cytometry (FC-VASP) and the ELISA-VASP technique, light transmission aggregometry (LTA) and VerifyNow-P2Y12 assay (VN-P2Y12). When using the ELISA-VASP PRI, the rate of patients with HPR in the overall ACS population was 15.5%, including a 27% rate in clopidogrel-treated patients and a 4% rate in prasugrel-treated patients. There was a strong correlation between ELISA-VASP PRI and FC-VASP PRI (r = 0.83, r2 = 0.68 p < 0.0001) with an area under the receiver-operating characteristics (ROC) curve to identify HPR (VASP-PRI >50% with FC-VASP) of 0.94, p<0.0001. The threshold of 60% for ELISA-VASP PRI provided the best accuracy (likelihood ratio= 23.67) to identify patients with HPR when compared to FC-VASP, LTA or VN-P2Y12 assays. In conclusion, ELISA-VASP is a fast, easy-to-use and specific test to identify HPR in ACS patients on thienopyridines. A 60% threshold value displays the best accuracy to identify HPR in these patients.

Platelets, inflammation and anti-inflammatory effects of antiplatelet drugs in ACS and CAD

Platelets play a pivotal role in chronic inflammation leading to progression of atherosclerosis and acute coronary events. Recent discoveries on novel mechanisms and platelet-dependent inflammatory targets underpin the role of platelets to maintain a chronic inflammatory condition in cardiovascular disease. There is strong and clinically relevant crosslink between chronic inflammation and platelet activation. Antiplatelet therapy is a cornerstone in the prevention and treatment of acute cardiovascular events. The benefit of antiplatelet agents has mainly been attributed to their direct anti-aggregatory impact. Some anti-inflammatory off-target effects have also been described. However, it is unclear whether these effects are secondary due to inhibition of platelet activation or are caused by direct distinct mechanisms interfering with inflammatory pathways. This article will highlight novel platelet associated targets that contribute to inflammation in cardiovascular disease and elucidate mechanisms by which currently available antiplatelet agents evolve anti-inflammatory capacities, in particular by carving out the differential mechanisms directly or indirectly affecting platelet mediated inflammation. It will further illustrate the prognostic impact of antiplatelet therapies by reducing inflammatory marker release in recent cardiovascular trials.

Pharmacodynamic effects of standard dose prasugrel versus high dose clopidogrel in non-diabetic obese patients with coronary artery disease

Increased body weight is independently associated with impaired clopidogrel pharmacodynamic (PD) response. Prasugrel has more potent PD effects compared with clopidogrel, although its PD effects in obese patients are unknown. The aim of this prospective, randomised, study was to compare the PD effects of standard-dose prasugrel [60 mg loading dose (LD)/10 mg daily maintenance dose (MD)] with highdose clopidogrel (900 mg LD/150 mg daily MD) in non-diabetic obese [body mass index (BMI) ≥30 kg/m2] patients, with coronary artery disease (CAD) on aspirin therapy. PD assessments (baseline, 2 hours post-LD and 6 ± 2 days after MD) were conducted using four platelet function assays, and the platelet reactivity index (PRI) assessed by VASP was used for sample size estimation. A total of 42 patients with a BMI of 36.42 ± 5.6 kg/m2 completed the study. There were no differences in baseline PD measures between groups. At 2 hours post-LD, prasugrel was associated with lower PRI compared with clopidogrel (24.3 ± 5.5 vs 58.7 ± 5.7, p≤0.001), with consistent findings for all assays. At one-week, PRI values on prasugrel MD were lower than clopidogrel MD without reaching statistical significance (34.7 ± 5.8 vs 42.9 ± 5.8, p=0.32), with consistent findings for all assays. Accordingly, rates of high on-treatment platelet reactivity were markedly reduced after prasugrel LD, but not after MD. In conclusion, in non-diabetic obese patients with CAD, standard prasugrel dosing achieved more potent PD effects than high-dose clopidogrel in the acute phase of treatment, but this was not sustained during maintenance phase treatment. Whether an intensified prasugrel regimen is required in obese patients warrants investigation.

Early ambulance initiation versus in-hospital initiation of high dose clopidogrel in ST-segment elevation myocardial infarction

Pre-hospital infarct diagnosis gives the opportunity to start anti-platelet and anti-thrombotic agents before arrival at the PCI centre. However, more evidence is necessary to demonstrate whether high dose (HD) clopidogrel (600 mg) administered in the ambulance is associated with improved initial patency of the infarct related vessel (IRV) and/or clinical outcome compared to in-hospital initiation of HD clopidogrel. From 2001 until 2009 all consecutive ST-Segment Elevation Myocardial Infarction (STEMI) patients who underwent pre-hospital diagnosis and therapy in the ambulance were prospectively included in our single-centre cohort study. We compared initial patency of the IRV and clinical outcome in patients treated from 2001 until June 2006 (in-hospital HD clopidogrel) with patients treated from July 2006 until 2009 (ambulance HD clopidogrel). A total of 2,475 patients with STEMI were registered; of these 1,110 (44.8%) received in-hospital HD clopidogrel and 1,365 (55.2%) received ambulance HD clopidogrel. Ambulance HD clopidogrel was not independently associated with initial patency (TIMI-2/3-flow pre-PCI (odds ratio: 1.18, 95% confidence interval [CI] 0.96–1.44); however, it was associated with fewer recurrent myocardial infarctions at 30 days (hazard ratio [HR]: 0.45, 95% CI 0.22–0.93) and at one year (HR: 0.45, 95% CI 0.25–0.80). No difference in TIMI 2/3 flow post-PCI, major bleeding, mortality, MACE – and the combination of mortality and recurrent myocardial infarction at 30-days and at one year was present between the two groups. In conclusion, early in-ambulance as compared to in-hospital initiation of HD clopidogrel in STEMI patients did not improve initial patency of the IRV or clinical outcome, except for a reduction of recurrent myocardial infarction. Therefore, early administration of HD clopidogrel seems to have net clinical benefit for these patients .

Baseline platelet parameters for predicting early platelet response and clinical outcomes in patients with non-cardioembolic ischemic stroke treated with clopidogrel

Purpose

The present study investigated whether routine baseline platelet parameters(BPPs) detected before clopidogrel therapy in acute non-cardioembolic ischemic stroke(NCIS) could predict early platelet response and future clinical outcomes.

Results

The CYP2C19 polymorphisms constituted independent risk factors for LCR. The number of female patients, the incidence of diabetes mellitus (DM), the level of low-density lipoprotein(LDL) cholesterol, and the neutrophil-to-lymphocyte ratio(NLR) were significantly high in the clinical clopidogrel resistance (CCR) group. However, none of the BPPs had a significant association with laboratory clopidogrel resistance (LCR) or discriminated with the cut-off values regarding LCR or CCR. The patients were divided into two groups according to the average mean platelet volume(MPV) or platelet count(PC). We found that the HbA1c level, the number of female patients, and the CCR were higher in the groups with elevated MPV (≥ 10.6fL) and PC (≥ 235 × 10⁹/L); the LCR, the NIHSS score at discharge, and elevated MPV and PC were risk predictors for CCR.

Materials and Methods

This study included 196 patients with acute NCIS who underwent routine blood tests upon admission, were treated with clopidogrel, and were followed up for 6 months. Early platelet response was assessed and the CYP2C19 genetic variants were screened for. All participants were categorized into either laboratory clopidogrel resistance(LCR) or clinical clopidogrel resistance (CCR) groups.

Conclusions

Elevated baseline MPV and PC before clopidogrel therapy, as well as CYP2C19 gene variants, should be included in a risk algorithm for NCIS. Furthermore, other nongenetic clinical risk factors should be assessed for optimal prediction of the risk for thrombotic events because of individual variability in platelet response to clopidogrel.

Thienopyridines in Acute Coronary Syndrome

OBJECTIVE:

To evaluate the safety and efficacy of the thienopyridines in order to identify their current place in therapy for the treatment of acute coronary syndrome (ACS).

DATA SOURCES:

Literature was accessed through MEDLINE (1966-October 2010 week 1), EMBASE (1980–2010 week 40), and a bibliographic review of published articles using the search terms acute coronary syndrome, clopidogrel, and prasugrel. Articles were limited to clinical trials conducted in humans and published in the English language.

STUDY SELECTION AND DATA EXTRACTION:

Head-to-head clinical trials evaluating the safety and efficacy of the thienopyridines in patients with ACS were critically reviewed. Trials evaluating ticlopidine were excluded due to its limited clinical use.

DATA SYNTHESIS:

Thienopyridines are an integral part of the treatment of ACS. Prior to the approval of prasugrel, clopidogrel was considered the agent of choice due to safety concerns associated with ticlopidine. A randomized controlled trial comparing prasugrel and clopidogrel has demonstrated superior efficacy with prasugrel, and post hoc analyses suggest additional benefit with prasugrel is derived in patients with ST-segment elevation myocardial infarction and patients with diabetes. However, safety concerns exist linking prasugrel with an increased risk of bleeding, which diminishes its advantage in elderly patients, underweight patients, and those with a history of stroke. Pharmacokinetic and pharmacodynamic studies discussing differences in response variability, platelet inhibition, interactions with proton pump inhibitors, and genetic factors between the thienopyridines are numerous, although more clinical data are needed to determine clinical implications.

CONCLUSIONS:

Clinical trial data have suggested prasugrel is superior to clopidogrel at preventing ischemic events in patients with ACS undergoing percutaneous coronary intervention. However, this coincides with an increased risk of bleeding. Clinicians must carefully interpret the current evidence, including limitations in study design and pharmacologic differences between agents, in order to balance the risks and benefits as new data become available.

Pretreatment with Antiplatelet Agents in the Setting of Percutaneous Coronary Intervention: When and Which Drugs?

Administering antiplatelet agents before coronary angiography to patients referred to elective or urgent percutaneous coronary intervention (PCI) requires a careful evaluation of advantages and disadvantages associated with platelet inhibition to avoid overtreatment on one side and undertreatment on the other. The delicate balance between ischemic protection and bleeding demands the ability to undertake risk stratification and individualized decisions, which is particularly challenging in the setting of ad hoc PCI and urgent procedures. This review analyzes the current evidence on pretreatment with oral and intravenous P2Y₁₂ inhibitors in patients undergoing coronary angiography with intent to undergo PCI.

High-Sensitive C-Reactive Protein Predicts Recurrent Stroke and Poor Functional Outcome: Subanalysis of the Clopidogrel in High-Risk Patients With Acute Nondisabling Cerebrovascular Events Trial

BACKGROUND AND PURPOSE

Minor stroke and transient ischemic attack are common disorders with high rate of subsequent disabling stroke. We aim to investigate the role of high-sensitive C-reactive protein (hsCRP) in predicting recurrent stroke and poor functional outcome.

METHODS

In the Clopidogrel in High-Risk Patients With Acute Nondisabling Cerebrovascular Events (CHANCE) trial, 3044 (59%) consecutive patients from 73 (64%) prespecified centers had hsCRP levels measured. The primary outcome was any stroke within 90 days. The secondary outcome included combined vascular events and dependence or death defined as modified Rankin Scale score of 2 to 6 at 90 days and a new vascular event during 1-year follow-up. The associations of hsCRP with recurrent stroke and functional outcome were analyzed by using Cox proportional hazards and logistic regression models.

RESULTS

Elevated hsCRP (>3.0 mg/L) was observed in 32% of the study population. Patients with hsCRP >3 mg/L had an increased risk of recurrent stroke (adjusted hazard ratio, 1.46; 95% confidence interval, 1.08-1.98; P=0.039), ischemic stroke and combined vascular events, and poor functional outcome (adjusted odds ratio, 1.68; 95% confidence interval, 1.22-2.32; P=0.002) compared with those with hsCRP <1 mg/L within 90-day follow-up period. High hsCRP levels also independently predicted recurrent stroke during 1-year follow-up. There was no interaction of hsCRP levels with randomized antiplatelet therapy.

CONCLUSIONS

High hsCRP levels predict recurrent stroke and poor functional outcome in acute patients with minor stroke or transient ischemic attack.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00979589.

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

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

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

BACKGROUND

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

OBJECTIVE

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

METHODOLOGY

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01860105.