Efficacy and safety of clopidogrel pretreatment before percutaneous coronary intervention with and without glycoprotein IIb/IIIa inhibitor use

Platelet glycoprotein IIb/IIIa inhibitor tirofiban in clopidogrel-naïve patients undergoing elective percutaneous coronary intervention

BACKGROUND

The safety of administration of tirofiban, a platelet glycoprotein IIb/IIIa inhibitor, followed by a clopidogrel loading dose in clopidogrel-naïve patients undergoing ad-hoc percutaneous coronary intervention (PCI) is not yet clear.

METHODS

In a retrospective observational cohort analysis, clopidogrel-naïve patients undergoing ad-hoc PCI who received a high-dose bolus of tirofiban (25 μg/kg) followed by a 600-mg clopidogrel loading dose (group 1) were compared with patients undergoing elective PCI who were pretreated with clopidogrel (group 2), between September 2014 and October 2021. The primary outcome was major adverse cardiovascular events (MACE) defined as the composite of death, myocardial infarction, stroke, target-lesion revascularisation and bleeding at 30 days. Secondary outcomes were MACE at 7 days and individual components of the primary outcome at 7 and 30 days.

RESULTS

A total of 1404 patients were included: 432 (31%) in group 1 and 972 (69%) in group 2. Median age was 69 years, and 28% were female. At 7‑day follow-up, MACE occurred in 1.4% in group 1 versus 3.0% in group 2 (p = 0.08). 30-day MACE were observed in 1.9% in group 1 and 4.2% in group 2 (p = 0.03). Secondary outcomes were comparable between the groups. Cox regression analysis, corrected for baseline differences, revealed no significant difference in the primary outcome (hazard ratio: 1.8; 95% confidence interval: 0.8-3.9).

CONCLUSION

Ad-hoc PCI in clopidogrel-naïve patients who were treated with high-dose bolus of tirofiban followed by a clopidogrel loading dose immediately after the procedure appeared to be safe.

Antiplatelet Therapy in Acute Coronary Syndrome

Antiplatelet agents have for decades been used to improve outcomes in patients with acute coronary syndromes and have become increasingly valued, not only for their antithrombotic properties but also for their anti-inflammatory effects. The drug class continues to evolve as novel agents with increasingly efficacious antiplatelet actions are identified. This review will discuss antiplatelet agents, including aspirin, the P2Y₁₂ receptor antagonists and the glycoprotein IIb/IIIa inhibitors, that are currently used to treat patients with unstable angina and myocardial infarction, focusing on their pharmacological properties and the clinical evidence supporting their use.

Impact of glycoprotein IIb/IIIa inhibitors on the efficacy and safety of ticagrelor compared with clopidogrel in patients with acute coronary syndromes: Analysis from the Platelet Inhibition and Patient Outcomes (PLATO) Trial

BACKGROUND

Ticagrelor reduced cardiovascular events compared with clopidogrel in PLATO without increasing overall major bleeding. We evaluated whether the use of glycoprotein IIb/IIIa inhibitor (GPI) impacts the relative efficacy and safety of ticagrelor compared with clopidogrel.

METHODS

PLATO randomized 18,624 subjects with acute coronary syndrome to ticagrelor versus clopidogrel. The primary efficacy end point was cardiovascular death/myocardial infarction/stroke, and the primary safety end point was major bleeding. The use of GPI was at the physician's discretion and open-label. We evaluated outcomes at 30 days stratified by GPI use in the subgroup of 9,983 patients who underwent percutaneous coronary intervention (PCI) within 72 hours.

RESULTS

A total of 4,020 (40%) received a GPI. Those receiving a GPI were more likely to be younger, be male, and undergo multivessel PCI. There was no interaction between treatment and GPI use for the primary efficacy and safety end points. Patients treated without GPI had a lower rate of definite stent thrombosis and higher rate of minor/major bleeding with ticagrelor compared with clopidogrel (P < .05), whereas there was no such difference with GPI (P interaction < .05).

CONCLUSIONS

In patients with acute coronary syndrome undergoing early PCI, the efficacy and safety of ticagrelor as compared with clopidogrel were not modified by GPI use according to the primary efficacy and safety end point of the trial, although there were indications of greater benefit on definite stent thrombosis and more major or minor bleeding with ticagrelor in patients without (vs with) GPI treatment.

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

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

Effectiveness of Pretreatment With Dual Oral Antiplatelet Therapy

Several observational studies, randomized controlled trials, and meta-analyses suggested that pretreatment with clopidogrel in addition to aspirin could reduce the rate of ischemic events, especially in the setting of acute coronary syndromes. Newer P2Y12 inhibitors like prasugrel and ticagrelor, which provide faster and stronger platelet inhibition compared with clopidogrel, would enhance the benefits of pretreatment. However, 2 recent randomized trials, A Comparison of Prasugrel at PCI or Time of Diagnosis of Non-ST Elevation Myocardial Infarction and the Administration of Ticagrelor in the Cath Lab or in the Ambulance for New ST Elevation Myocardial Infarction to Open the Coronary Artery studies, aimed at assessing the effects of the timing of administration of novel P2Y12 inhibitors in acute coronary syndromes, failed to meet their primary end points. In this report, we review clinical data on pretreatment with dual oral antiplatelet therapy and comment on some criticisms raised from recent trials.

A pharmacodynamic comparison of 5 anti-platelet protocols in patients with ST-elevation myocardial infarction undergoing primary PCI

Background

Despite advances in anti-platelet treatments, there still exists an early increase in both ischemic as well as bleeding events following primary PCI in patients with ST-elevation myocardial infarction (STEMI). Platelet inhibition data of different anti-platelet treatments in the acute phase of a myocardial infarction might offer some insight into these problems. The aim of this study was to evaluate the pharmacodynamic profile of 5 different anti-platelet treatments in the acute phase of STEMI in patients undergoing primary PCI.

Methods

A total of 223 STEMI patients undergoing primary PCI were prospectively included. Patients received either pre-hospital clopidogrel only, pre-hospital clopidogrel followed by prasugrel switch in the cath lab, prasugrel treatment only, pre-hospital clopidogrel followed by ticagrelor switch in the cath lab or pre-hospital ticagrelor only. Platelet reactivity was measured serially using vasodilator-stimulated phosphoprotein (VASP).

Results

Patients receiving pre-hospital clopidogrel followed by prasugrel switch showed similar platelet inhibition data as patients receiving prasugrel only, with more than 90% being good responders the day after PCI. Average time from prasugrel administration to a VASP value of <50% was 1.5 hours. In patients receiving pre-hospital ticagrelor, 50% were good responders at completion of PCI and average time to a VASP-value of <50% was 2.3 hours. Only 32% of patients receiving clopidogrel only were responders the day after PCI.

Conclusions

Switching from an upstream bolus dose of clopidogrel to prasugrel at the time of PCI, appeared as a safe and feasible option with no tendency for overshoot or attenuation of platelet inhibition. Pre-hospital administration of ticagrelor was associated with a 50% good responder rate at completion of PCI.

Dual antiplatelet therapy with prasugrel or ticagrelor versus clopidogrel in interventional cardiology

For several years, clopidogrel plus aspirin has been the dual antiplatelet therapy (DAPT) of choice for patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) with stent implantation. More recently, prasugrel and ticagrelor have demonstrated greater efficacy than clopidogrel. In TRITON-TIMI 38, the risk of TIMI major bleeding unrelated to coronary artery bypass graft (CABG) surgery was similar for prasugrel and clopidogrel after excluding subgroups with increased bleeding risk (previous stroke or transient ischemic event; age ≥75 years; weight <60 kg). In the PLATO trial, rates of TIMI major bleeding were similar for ticagrelor and clopidogrel, but ticagrelor was associated with a significantly higher rate of non-CABG-related TIMI major bleeding. Current evidence suggests that prasugrel or ticagrelor plus aspirin should be the DAPT of choice in patients with ACS undergoing PCI unless they are at particularly high risk of bleeding. No studies have yet compared prasugrel and ticagrelor in ACS patients, however prasugrel and ticagrelor have different side effect profiles, and the choice of agent should be made either as a default choice and/or on an individual patient basis. Ongoing trials in ACS patients will increase the evidence base for new P2Y(12) receptor inhibitors and help to establish the most effective DAPT regimens.

Clinical outcomes, health resource use, and cost in patients with early versus late dual or triple anti-platelet treatment for acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS) guidelines recommend early dual anti-platelet therapy (thienopyridines + acetylsalicylic acid [aspirin]). However, triple therapy (thienopyridines + aspirin + glycoprotein IIb/IIIa receptor inhibitors [GRIs]) has shown benefit in clinical trials.

OBJECTIVE

This study assessed real-world ACS treatment patterns and outcomes in the acute care setting.

STUDY DESIGN

A retrospective analysis of patients admitted to hospital with ACS (index event) from January 2007 to December 2009 was conducted (Thomson's MarketScan Hospital Drug Database).

PATIENTS

Eligible patients were ≥18 years of age, of either sex, and had primary admission and discharge diagnoses of ACS.

OUTCOME MEASURES

Cohorts were defined by anti-platelet treatment and then by the timing of treatment initiation (early initiation: within ≤2 days of admission; late initiation: ≥2 days post-admission). Patient characteristics, clinical outcomes, resource utilization, and costs were assessed using descriptive statistics.

RESULTS

A total of 249,907 eligible patients were placed into four treatment cohorts (aspirin assumed for all patients): aspirin only; clopidogrel only (dual therapy); GRI only (dual therapy); and clopidogrel + GRI (triple therapy). Patients in the 'clopidogrel-only' cohort were more likely to be older, female, and have more co-morbidities than those in other cohorts; stroke (6.2 %) and re-hospitalization (15.4 %) rates were higher than in the 'GRI-only' and 'triple therapy' cohorts. The GRI-only cohort had higher major bleeding rates (3.3 %), mortality (7.6 %), and costs ($US21,975 [year 2010 values]) than the clopidogrel-only and triple-therapy cohorts. Late initiation cohorts were more likely to be older, female, and have more co-morbidities than early initiation cohorts. Major bleeding was more likely with GRI-only patients (regardless of initiation timing) than with other cohorts. Late-treated clopidogrel-only patients had higher rates of stroke (6.9 %), ACS-related re-admissions (6.1 %), and all-cause re-admissions (15.9 %) than other cohorts. Late treatment was associated with longer length of stay and significantly higher costs.

CONCLUSIONS

Real-world anti-platelet treatment patterns are consistent with ACS guidelines recommending early initiation and selective GRI use. In contrast to recommendations, some outcomes were improved with triple therapy compared with dual therapy.

ED administration of thienopyridines in non-ST-segment elevation myocardial infarction: results from the NCDR

OBJECTIVE

American Heart Association/American College of Cardiology guidelines recommend that patients with definite unstable angina or non-ST-segment elevation myocardial infarction (NSTEMI) receive dual antiplatelet therapy on presentation to the hospital when undergoing early invasive management or "as soon as possible" after admission when being managed conservatively. The guidelines do not specify whether these medications should be administered in the emergency department (ED). Our aim was to determine whether ED administration of a thienopyridine was associated with clinical outcomes among patients with NSTEMI.

METHODS

We examined thienopyridine use in 39454 patients with NSTEMI who received a thienopyridine within 24 hours of presentation in the National Cardiovascular Data Registry's Acute Coronary Treatment and Intervention Outcomes Network-Get With The Guidelines Registry from January 2007 to June 2010. Patients who were not seen initially in the ED, were transferred in, or were missing time data were excluded. We analyzed the association between ED administration of thienopyridines and outcomes and patient demographics.

RESULTS

Of the cohort receiving a thienopyridine within 24 hours, 9534 (24.2%) received it in the ED. Emergency department administration of a thienopyridine was not associated with in-hospital major bleeding (multivariable adjusted odds ratio, 0.99; 95% confidence interval, 0.91-1.09) or in-hospital mortality (adjusted 1.02; 95% confidence interval, 0.86-1.20). Independent predictors most strongly associated with ED thienopyridine administration were elevated troponin, ED length of stay, prior percutaneous coronary intervention, and initial electrocardiogram showing ischemic changes.

CONCLUSIONS

There was no association between ED thienopyridine administration and in-hospital major bleeding or mortality. Emergency department length of stay, electrocardiographic changes, and elevated troponin were associated with ED thienopyridine administration.

Integrin αIIbβ3: from discovery to efficacious therapeutic target

From the initial description of platelets in 1882, their propensity to aggregate and to contribute to thrombosis was apparent. Indeed, excessive platelet aggregation is associated with myocardial infarction and other thrombotic diseases whereas Glanzmann thrombasthenia, in which platelet aggregation is reduced, is a bleeding syndrome. Over the last half of the 20th century, many investigators have provided insights into the cellular and molecular basis for platelet aggregation. The major membrane protein on platelets, integrin αIIbβ3, mediates this response by rapidly transiting from its resting to an activated state in which it serves as a receptor for ligands that can bridge platelets together. Monoclonal antibodies, natural products, and small peptides were all shown to inhibit αIIbβ3 dependent platelet aggregation, and these inhibitors became the forerunners of antagonists that proceeded through preclinical testing and into large patient trials to treat acute coronary syndromes, particularly in the context of percutaneous coronary interventions. Three such αIIbβ3 antagonists, abciximab, eptifibatide, and tirofiban, received Food and Drug Administration approval. Over the past 15 years, millions of patients have been treated with these αIIbβ3 antagonists and many lives have been saved by their administration. With the side effect of increased bleeding and the development of new antithrombotic drugs, the use of αIIbβ3 antagonists is waning. Nevertheless, they are still widely used for the prevention of periprocedural thrombosis during percutaneous coronary interventions. This review focuses on the biology of αIIbβ3, the development of its antagonists, and some of the triumphs and shortcomings of αIIbβ3 antagonism.

Combination of cilostazol and clopidogrel attenuates rat critical limb ischemia

BACKGROUND AND AIM

Procedural failure and untoward clinical outcomes after surgery remain problematic in critical limb ischemia (CLI) patients. This study tested a clopidogrel-cilostazol combination treatment compared with either treatment alone in attenuating CLI and improving CLI-region blood flow in rats.

METHODS

Male Sprague-Dawley rats (n = 40) were equally divided into five groups: control, CLI induction only, CL I + cilostazol (12.0 mg/day/kg), CLI + clopidogrel (8.0 mg/kg/day) and CLI + combined cilostazol-clopidogrel. After treatment for 21 days, Laser Doppler imaging was performed.

RESULTS

On day 21, the untreated CLI group had the lowest ratio of ischemic/normal blood flow (p < 0.001). Inflammation measured by VCAM-1 protein expression; oxidative stress; PAI-1, MMP-9 and TNF-α mRNA expressions; and immunofluorescence staining (IF) of CD68+ cells was lower with combined treatment than with the other treatments, and lower in the two single-treatment groups than the untreated CLI group (all p < 0.01). Anti-inflammatory mRNA expression of interleukin-10, and eNOS showed a reverse pattern among these groups. Apoptosis measured by Bax, caspase-3 and PARP; and muscle damage measured by cytosolic cytochrome-C, and serum and muscle micro-RNA-206 were all lowest with combination treatment, and the two single-treatment groups showed lower values than the untreated group (all p < 0.001). Angiogenesis measured by eNOS, IF staining of CD31+ and vWF + cells; and number of vessels in CLI region were highest with combination treatment and higher in the single-treatment groups than the untreated group (all p < 0.001).

CONCLUSION

Combined cilostazol-clopidogrel therapy is superior to either agent alone in improving ischemia in rodent CLI.

P2Y12 antagonists in acute coronary syndrome: in whom should they be started, and when?

Acute coronary syndromes reflect a spectrum of disease related, most commonly, to the sudden reduction in blood flow to a portion of myocardium. The underlying pathogenesis of the reduction in coronary flow is related to the sudden rupture of an atherosclerotic plaque, with subsequent thrombus formation leading to either vascular occlusion or microembolization. Clinicians combat this process with antithrombotic therapy, which typically includes both anticoagulant and antiplatelet therapy, and mechanical therapies, such as percutaneous coronary interventions, nearly always using stents. This review focuses on P2Y12 antagonists as one component of our armamentarium of antiplatelet therapies, specifically on data addressing in whom, when, which agent, and in what dose such agents should be administered.

Effect of clopidogrel pretreatment on ischemic complications of percutaneous coronary intervention among bivalirudin-treated patients (from the EVENT registry)

Although clopidogrel pretreatment benefits patients undergoing percutaneous coronary intervention (PCI) for acute coronary syndromes, these benefits are less well established among patients undergoing elective PCI--in particular, when they are treated with the direct thrombin inhibitor, bivalirudin. We used data from the multicenter Evaluation of Drug Eluting stents and ischemic Events registry to assess the association between clopidogrel pretreatment and PCI-related complications among patients undergoing elective PCI with bivalirudin as the antithrombotic regimen. The primary end point was the composite of in-hospital death or myocardial infarction. From January 2005 and December 2007, 4,681 patients underwent elective PCI at 55 United States centers, and 1,913 (41%) received bivalirudin as the planned anticoagulant. Clopidogrel pretreatment was used in 923 patients (48%). The incidence of in-hospital death or myocardial infarction was similar among patients who did and did not receive clopidogrel pretreatment (5.5% vs 5.8%, p = 0.83). This result was unchanged in propensity-adjusted analyses (adjusted odds ratio for pretreatment 0.91, 95% confidence interval 0.60 to 1.39, p = 0.66). Also, no differences were seen in the in-hospital bleeding events (1.0% vs 1.0%, p = 0.94) or 1-year ischemic complications between the 2 treatment groups (7.5% vs 8.3%, p = 0.26). In conclusion, among unselected patients undergoing elective PCI with bivalirudin as the planned anticoagulant, clopidogrel pretreatment was common but was not associated with a reduced risk of ischemic complications.

[Myocardial infarction: Role of new antiplatelet agents]

Thienopyridines have become the cornerstone of treatment of percutaneous coronary intervention although no survival benefit has ever been shown with clopidogrel despite increasing loading doses. Newly developed P2Y(12) inhibitors are more potent, more predictable and have a faster onset of action than clopidogrel, characteristics that make them particularly attractive for high-risk PCI. Four new P2Y(12) inhibitors have been tested each of them having particular individual properties. Prasugrel is an oral prodrug leading to irreversible blockade of the P2Y(12) receptor and is approved worldwide for ACS PCI. Ticagrelor is a direct-acting and reversible inhibitor of the P2Y(12) receptor with potentially more pleiotropic effects. Cangrelor is an intravenous direct and reversible inhibitor of the P2Y(12) receptor providing the highest level of inhibition and elinogrel is an intravenous and oral P2Y(12) antagonist with a direct and reversible action. Both prasugrel and ticagrelor, opposed to clopidogrel, have shown that stronger P2Y(12) inhibition led respectively to significant 19 % and 16 % relative risk reduction of a similar primary endpoint combining cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. Both drugs showed a significant 0.6 % absolute excess of TIMI major bleeding not related to CABG surgery. The effect of these new compounds is prompt, predictable and powerful as compared to clopidogrel. Their net benefit is particularly marked in PCI for STEMI patients, in which there is no significant increase in major bleeding when compared with clopidogrel. However, because in clinical trials patients perceived to be at higher risk for bleeding usually are excluded, the risk of major and even fatal bleeding might even be higher in a "real-world" setting i.e. in the elderly patient with comorbidities.

A comparison of prasugrel at the time of percutaneous coronary intervention or as pretreatment at the time of diagnosis in patients with non-ST-segment elevation myocardial infarction: design and rationale for the ACCOAST study

BACKGROUND

The precise risk/benefit of thienopyridine pretreatment and the optimal dosage and timing of a thienopyridine loading dose (LD) for patients presenting with non-ST-segment elevation (NSTE) acute coronary syndromes are still being debated. Prasugrel, a novel thienopyridine, is an appropriate drug to address this issue as it provides predictably high and rapid inhibition of platelet aggregation.

STUDY DESIGN

ACCOAST is a phase 3, multicenter, parallel-group, double-blind, and event-driven study designed to compare 2 prasugrel LD schedules in patients with NSTE myocardial infarction who are scheduled for coronary angiography/percutaneous coronary intervention (PCI). Approximately 4,100 patients will be randomly assigned to an initial LD of 30 mg of prasugrel after the diagnosis followed by coronary angiography with an additional dose of 30 mg of prasugrel given at the time of PCI (pretreatment) or an LD of 60 mg of prasugrel given to patients undergoing PCI at the time of the procedure (non-pretreatment). All patients undergoing PCI will receive 5 or 10 mg of prasugrel daily. The primary objective is to test the hypothesis that prasugrel pretreatment is superior to prasugrel non-pretreatment as measured by a reduction in the composite end point of cardiovascular death, myocardial infarction, stroke, urgent revascularization, or glycoprotein IIb/IIIa inhibitor bailout through 7 days from randomization. Key safety end points include TIMI (Thrombolysis In Myocardial Infarction) major and minor bleeding risks.

CONCLUSIONS

The ACCOAST study will provide important evidence with regard to the benefits and risks of prasugrel pretreatment compared with administration of prasugrel at the time of PCI in patients with NSTE myocardial infarction.

Timing of thienopyridine loading and outcomes in the TRITON trial: the FDA Prasugrel Action Package outlook

TRial to assess Improvement in Therapeutic Outcomes by optimizing platelet inhibitioN with prasugrel Thrombolysis In Myocardial Infarction 38 (TRITON-TIMI 38) was a Phase 3, randomized, double blind, parallel-group, multinational head-to-head study of prasugrel vs. clopidogrel both on top of aspirin. The primary end point was the rate of cardiovascular death, nonfatal myocardial infarction (MI), or stroke, and was reached in 12.1% of patients treated with clopidogrel and in 9.9% of patients randomized to prasugrel, suggesting impressive vascular outcome benefit of prasugrel over clopidogrel. However, this overoptimistic interpretation of the trial results was challenged by the Food and Drug Administration (FDA) Secondary Review, which revealed several shortcomings with TRITON design and data interpretation including the front-loaded nature of prasugrel benefit. Recently, following approval with black box warning, the FDA posted the complete documentation set (Action Package), revealing additional information including the timing of loading in TRITON, and how it affects vascular outcomes. The detailed FDA communications revealed highly significant correlation of the loading dose delay and primary efficacy outcomes favoring prasugrel. Indeed, when patients in TRITON were loaded early, or pretreated, the benefit of prasugrel was nonexistent. However, the longer it takes during or especially after PCI to load with thienopyridine, the more prasugrel benefit occurs. Considering that pretreatment with clopidogrel was disallowed; that three quarters of patients in TRITON were loaded during or after intervention; and that prasugrel was used at the 60-mg loading dose, which is over three times more potent than 300 mg clopidogrel, the claim of superiority of prasugrel over clopidogrel is not valid due to inappropriate use of clopidogrel.

Prasugrel as antiplatelet therapy in patients with acute coronary syndromes or undergoing percutaneous coronary intervention

The authors provide information on prasugrel, compare and contrast it with clopidogrel, and review the use of prasugrel in patients who require an antiplatelet agent.

Usefulness of pretreatment with high-dose clopidogrel in patients undergoing primary angioplasty for ST-elevation myocardial infarction

We evaluated the effect and optimal dose of clopidogrel pretreatment in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention (PPCI). The study included 383 consecutive patients with ST-elevation myocardial infarction who had undergone PPCI and were prospectively followed up for a prespecified primary end point of recurrent acute coronary syndrome, stent thrombosis, congestive heart failure, and/or death at 30 days. Of these patients, 217 (57%) received clopidogrel loading before and 166 (43%) after PPCI. A similar number received low (300 mg) and high (600 mg) clopidogrel doses before and after PPCI. Clopidogrel loading before, compared with after, PPCI was associated with a lower incidence of the primary end point (21.7% vs 33.7%, p = 0.008). Clopidogrel pretreatment remained a significant predictor of the primary outcome after adjusting for potential confounders (odds ratio 0.54, 95% confidence interval 0.42 to 0.91). When patients were further stratified into 4 groups according to the timing and dosage of clopidogrel loading, the incidence of the primary outcome was 16% and 27% in those receiving 600 and 300 mg before and 28% and 39% in those receiving 600 and 300 mg after PPCI, respectively (p for trend <0.01). In conclusion, both the timing and the dosage of clopidogrel loading are important and affect the outcome in patients with ST-elevation myocardial infarction undergoing PPCI.

Influence of timing of clopidogrel treatment on the efficacy and safety of bivalirudin in patients with non-ST-segment elevation acute coronary syndromes undergoing percutaneous coronary intervention: an analysis of the ACUITY (Acute Catheterization and Urgent Intervention Triage strategY) trial

OBJECTIVES

This study sought to determine if the efficacy of bivalirudin alone versus heparin plus a glycoprotein (GP) IIb/IIIa inhibitor is dependent upon the duration of clopidogrel pre-treatment in patients undergoing percutaneous coronary intervention (PCI) in the ACUITY (Acute Catheterization and Urgent Intervention Triage strategY) trial.

BACKGROUND

The administration of a clopidogrel loading dose several hours before PCI reduces the risk of periprocedural thrombotic events.

METHODS

Patients with an acute coronary syndrome were randomized to heparin plus a GP IIb/IIIa inhibitor (control), bivalirudin plus a GP IIb/IIIa inhibitor, or bivalirudin alone. Dose and timing of clopidogrel were left to the investigator's discretion.

RESULTS

Of 13,819 patients randomized, 7,789 underwent PCI. When clopidogrel was initiated at any time before angiography or within 30 min after PCI, randomization to bivalirudin alone (n = 2,284) or control (n = 2,189) was associated with similar ischemic outcomes (8.2% vs. 8.3%, risk ratio: 0.98, 95% confidence interval: 0.81 to 1.20). Those patients who received clopidogrel >30 min after PCI or not at all experienced an increase in ischemic events when randomized to bivalirudin alone (n = 290) versus control (n = 317) (14.1% vs. 8.5%, risk ratio: 1.66, 95% confidence interval: 1.05 to 2.63). Major bleeding was significantly less frequent in patients treated with bivalirudin alone.

CONCLUSIONS

This post-hoc analysis suggests that in acute coronary syndrome patients, as long as clopidogrel is administered before or within 30 min of PCI treatment with bivalirudin alone is similarly effective to heparin plus a GP IIb/IIIa inhibitor in suppressing 30-day ischemic events with significantly less bleeding. If it is anticipated that clopidogrel will be given late or not at all after PCI, bivalirudin alone may be associated with worse ischemic outcomes. (Comparison of Angiomax Versus Heparin in Acute Coronary Syndromes; NCT00093158).

Contemporary issues on clopidogrel therapy

In this paper, data from available studies regarding some contemporary issues on clopidogrel therapy are analyzed. In particular, the following clinical questions have been considered and addressed: (a) Is early clopidogrel treatment needed in patients with acute coronary syndromes treated medically or undergoing percutaneous coronary intervention (PCI)? (b) What is the optimal clopidogrel loading dose in patients undergoing PCI? (c) Is pre-treatment with clopidogrel before PCI needed, or can clopidogrel loading be given in the catheter laboratory before intervention, but after coronary anatomy is known? (d) What is the optimal clopidogrel strategy in patients on chronic clopidogrel therapy undergoing PCI? (e) Does the degree of clopidogrel response influence clinical outcome in patients undergoing PCI?

Use of clopidogrel in the reduction of myocardial damage during percutaneous coronary intervention

It is estimated that approximately a quarter of patients undergoing coronary intervention may have significant post-procedural creatinine (CK)/creatinine kinase myocardial band (CK-MB) elevations and approximately half may have post-procedural troponin elevations. Current data suggest that periprocedural infarction is associated with short-, intermediate-, and long-term adverse outcomes, most notably mortality. This review examines the role of clopidogrel in decreasing periprocedural myonecrosis following percutaneous coronary intervention (PCI). Clopidogrel is an important pharmacologic agent used to reduce myocardial infarction post-coronary intervention as assessed directly by the evaluation of cardiac biomarkers and indirectly by the evaluation of short-term ischemic events. The optimal dose of clopidogrel is considered to be at least 300 mg given 6 to 15 hours prior to PCI but there is considerable evidence to suggest that a loading dose of 600 mg given 2 to 6 hours prior to PCI may be more efficacious in limiting post-coronary intervention events. The benefit obtained from clopidogrel appears independent of and incremental to that of other antiplatelet and antithrombotic agents used during and after coronary intervention.