A direct comparison of tirofiban and abciximab during percutaneous coronary revascularization and stent placement: rationale and design of the TARGET study

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet agents may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the benefits and harms of antiplatelet agents in people with any form of CKD, including those with CKD not receiving renal replacement therapy, patients receiving any form of dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 13 July 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet agents versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data were pooled using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 113 studies, enrolling 51,959 participants; 90 studies (40,597 CKD participants) compared an antiplatelet agent with placebo or no treatment, and 29 studies (11,805 CKD participants) directly compared one antiplatelet agent with another. Fifty-six new studies were added to this 2021 update. Seven studies originally excluded from the 2013 review were included, although they had a follow-up lower than two months. Random sequence generation and allocation concealment were at low risk of bias in 16 and 22 studies, respectively. Sixty-four studies reported low-risk methods for blinding of participants and investigators; outcome assessment was blinded in 41 studies. Forty-one studies were at low risk of attrition bias, 50 studies were at low risk of selective reporting bias, and 57 studies were at low risk of other potential sources of bias. Compared to placebo or no treatment, antiplatelet agents probably reduces myocardial infarction (18 studies, 15,289 participants: RR 0.88, 95% CI 0.79 to 0.99, I² = 0%; moderate certainty). Antiplatelet agents has uncertain effects on fatal or nonfatal stroke (12 studies, 10.382 participants: RR 1.01, 95% CI 0.64 to 1.59, I² = 37%; very low certainty) and may have little or no effect on death from any cause (35 studies, 18,241 participants: RR 0.94, 95 % CI 0.84 to 1.06, I² = 14%; low certainty). Antiplatelet therapy probably increases major bleeding in people with CKD and those treated with haemodialysis (HD) (29 studies, 16,194 participants: RR 1.35, 95% CI 1.10 to 1.65, I² = 12%; moderate certainty). In addition, antiplatelet therapy may increase minor bleeding in people with CKD and those treated with HD (21 studies, 13,218 participants: RR 1.55, 95% CI 1.27 to 1.90, I² = 58%; low certainty). Antiplatelet treatment may reduce early dialysis vascular access thrombosis (8 studies, 1525 participants) RR 0.52, 95% CI 0.38 to 0.70; low certainty). Antiplatelet agents may reduce doubling of serum creatinine in CKD (3 studies, 217 participants: RR 0.39, 95% CI 0.17 to 0.86, I² = 8%; low certainty). The treatment effects of antiplatelet agents on stroke, cardiovascular death, kidney failure, kidney transplant graft loss, transplant rejection, creatinine clearance, proteinuria, dialysis access failure, loss of primary unassisted patency, failure to attain suitability for dialysis, need of intervention and cardiovascular hospitalisation were uncertain. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, including prasugrel, ticagrelor, different doses of clopidogrel, abciximab, defibrotide, sarpogrelate and beraprost.

AUTHORS' CONCLUSIONS

Antiplatelet agents probably reduced myocardial infarction and increased major bleeding, but do not appear to reduce all-cause and cardiovascular death among people with CKD and those treated with dialysis. The treatment effects of antiplatelet agents compared with each other are uncertain.

Early Thrombosuction and Tirofiban Use in Knee and Below-Knee Arterial Thrombosis

BACKGROUND Acute limb ischemia (ALI) is a clinical entity with a high rate of morbidity and mortality. Despite advances and variety of its management, there is still no criterion standard treatment. The goal of this study was to evaluate the effect of tirofiban use on the early and 6-month prognosis of patients with knee and below-knee arterial thrombosis who were treated with percutaneous thrombosuction (PT) within 24 h. MATERIAL AND METHODS Data of consecutive ALI patients who were diagnosed with popliteal and infra-popliteal arterial thrombosis and underwent PT procedure within 24 h between January 2010 and September 2015 were evaluated retrospectively. Patients were separated into 2 groups according to tirofiban usage. RESULTS A total of 105 patients (mean age 67±16; 53% men) were included in the study. Atrial fibrillation (n 64, 61%) and hypertension (n 60, 57%) were the most frequent comorbidities in patients with thromboembolic events. A significantly higher rate of distal embolization (6% vs. 16%; p=0.01) and slow-flow (17% vs. 30%; p<0.01) developed in patients who were not treated with tirofiban after the PT procedure. Although major and minor bleeding were more frequent in the tirofiban group, only the rate minor bleeding was statistically significant (29% vs. 9%, p=0.001). Reverse embolic event ratio was similar in both groups. Although there was a higher rate of amputation in patients not treated with tirofiban, the difference was not significant. CONCLUSIONS Adding tirofiban to PT reduces angiographic thromboembolic complications. Usage of tirofiban in patients prone to thromboembolic events may be useful for improving success of the PT procedure, with a reasonable bleeding ratio.

Outcome of multivessel coronary intervention in the contemporary percutaneous revascularization era

Clinical outcomes after multivessel versus single-vessel percutaneous coronary intervention (PCI) in the era of stents, glycoprotein IIb/IIIa inhibitors, and clopidogrel pretreatment have not been well studied. Thus, we compared outcomes from the Do Tirofiban and ReoPro Give Similar Efficacy Outcome Trial (TARGET) for patients who underwent multivessel versus single-vessel PCI and separately considered the effect of acute coronary syndromes on the results. Composite clinical outcomes (death, myocardial infarction, and target vessel revascularization) were evaluated at 30 days and 6 months and mortality at 1 year. Safety analysis included in-patient major and minor bleeding. Despite similar baseline characteristics, patients who underwent multivessel PCI (n = 775) had significantly higher 30-day and 6-month composite event rates than did those who were treated in a single coronary artery territory (n = 3,969). This association remained significant at 30 days (hazard ratio 1.57, 95% confidence interval 1.06 to 2.33, p = 0.025) after using propensity matching to minimize confounding factors. The higher event rate was primarily due to an increase in periprocedural myocardial infarction. However, there were no significant differences in propensity-matched ischemic outcomes at 6 months and 1 year or in bleeding. In addition, in a propensity-matched analysis that included 810 patients with acute coronary syndrome, multivessel stenting resulted in numerically more ischemic events than did single-vessel stenting, although this did not reach statistical significance (hazard ratio 1.32, 95% confidence interval 0.85 to 2.05, p = 0.221). In conclusion, multivessel PCI was more often associated with periprocedural myocardial infarction than single-vessel intervention, although this did not translate into higher 1-year mortality. A randomized trial comparing multivessel PCI with staged or surgical revascularization is warranted.

Choice of delta: requirements and reality--results of a systematic review

An essential problem in planning clinical non-inferiority or equivalence studies is the specification of the 'irrelevant difference' (irrelevance margin; delta). This quantifies the amount of non-inferiority or difference, respectively, between a new test therapy and an established standard treatment which is to be considered as tolerable. In the past, most recommendations and guidelines for clinical non-inferiority and equivalence studies contained only general statements and formulations concerning the specification of delta. The current unsatisfactory situation was the reason for performing a systematic review of published clinical non-inferiority and equivalence studies. It was the aim to gain an overview on the irrelevance margins used in such studies, and on reasons for choosing the particular margins. For the sake of comparability, the irrelevance margins were converted into standardized differences and odds ratios. Overall, there were 332 non-inferiority or equivalence trials obtained by means of an extensive literature search. The results of the systematic review show that current requirements on the choice of delta and the reality of recent clinical non-inferiority and equivalence trials differ substantially. In about one half of the trials a difference of 0.5 standard deviations or more was regarded as 'irrelevant' explicitly or implicitly. Estimates of standard-placebo differences formed the basis of the irrelevance margin in less than every tenth trial. Reasons for this very low proportion might be (1) the possibly resulting very small irrelevance margins, and (2) unsolved problems of the requirements themselves. Overall, it seems that a more global definition of 'irrelevance' might be warranted.

The relationship of obesity to ischemic outcomes following coronary stent placement in contemporary practice

OBJECTIVES

We analyzed the relationship of obesity, determined by body mass index (BMI), to short- and long-term outcomes in the TARGET trial.

BACKGROUND

: Previous studies have conflicting findings regarding the relationship of BMI to outcomes following percutaneous coronary intervention (PCI).

METHODS

The TARGET trial studied the use of glycoprotein (GP) IIb/IIIa inhibition in patients undergoing planned coronary stent placement.

RESULTS

Eighty-one percent of all patients were overweight (BMI > 25), 36% were obese (BMI > 30), and United States patients were more frequently obese (38.7% vs. 25.8%, P < 0.001). Obese patients had a similar 30-day ischemic event rate compared with nonobese patients, but less major bleeding (0.4% vs. 1.1%, P = 0.013). Six-month death and myocardial infarction rates were similar in obese and nonobese patients. There was a J-shaped relationship between 6-month target vessel revascularization (TVR) and BMI with the lowest incidence of TVR at BMI 27.5. Six-month TVR was higher in the morbidly (BMI > 35) obese (12.4% vs 8.7%, P < 0.05). In extremely (BMI > 32) obese patients, this relationship was more significant (TVR 11.3% vs. 8.5%, P = 0.007), particularly in patients <65 years of age (TVR 12.3% vs. 8.4%, P = 0.003).

CONCLUSION

The majority of patients undergoing PCI are overweight, especially in the United States. Extreme obesity is associated with a significant increase in TVR following intent-to-stent PCI, especially in patients <65 years of age. With routine use of GP IIb/IIIa inhibitors, other long- and short-term ischemic events are similar in obese and nonobese patients. However, obese patients have significantly less major bleeding.

Mortality at 1 year for the direct comparison of tirofiban and abciximab during percutaneous coronary revascularization: do tirofiban and ReoPro give similar efficacy outcomes at trial 1-year follow-up

AIMS

Compared with placebo, abciximab has been associated with mortality reduction at late follow-up. The TARGET trial was performed to test whether tirofiban and abciximab provide similar efficacy outcomes among patients undergoing non-emergent, stent-based percutaneous coronary intervention. We report here the 1-year mortality of the study population.

METHODS AND RESULTS

In 18 countries at 149 hospitals, 4,809 patients undergoing elective or urgent stent implantation were randomly assigned a bolus and infusion of tirofiban or abciximab. Ischaemic events were assessed at 30 days and 6 months and mortality was assessed at 1 year. We previously reported that abciximab was superior to tirofiban considering the composite rate of death or myocardial infarction at 30 days among all patients and at 6 months among those with an acute coronary syndrome (ACS). At 1-year follow-up death occurred in 46 (1.9%) patients who received tirofiban and 42 (1.7%) patients who received abciximab (hazard ratio 1.10, 95% CI 0.72-1.67; P=0.660). Mortality rates for patients with ACS were 2.3% with tirofiban vs. 2.2% with abciximab (hazard ratio 1.03, 95% CI 0.64-1.67; P=0.897) and those without ACS were 1.4 vs. 1.0% (hazard ratio 1.32, 95% CI 0.56-3.13; P=0.530).

CONCLUSION

At 1 year, tirofiban provided a similar level of survival benefit compared with abciximab.

The relation of renal function to ischemic and bleeding outcomes with 2 different glycoprotein IIb/IIIa inhibitors: the do Tirofiban and ReoPro Give Similar Efficacy Outcome (TARGET) trial

BACKGROUND

Renal function significantly impacts morbidity and mortality after a percutaneous coronary intervention. Platelet glycoprotein (GP) IIb/IIIa inhibitors reduce ischemic complications during percutaneous coronary intervention; little is known of whether their safety and efficacy are influenced by renal function. In particular, whether outcome differences exist between agents that are renally excreted (tirofiban) or not (abciximab) in patients with mild renal impairment is not known.

METHODS

The TARGET trial randomized 4623 patients to tirofiban or abciximab. In this analysis, patients were grouped in creatinine clearance quartiles (<70, 70-90, 90-114, >114 mL/min) and analyzed for efficacy and bleeding risk. Univariate and multivariate analyses were performed to identify interactions between GP IIb/IIIa inhibitor used and creatinine clearance with respect to ischemic outcomes and bleeding.

RESULTS

Using unadjusted logistic regression tests for trend, 30-day death/myocardial infarction/urgent target vessel revascularization was greater in patients with lower creatinine clearances (7.3%, 8.5%, 5.1%, and 5.8%, P = .005), as were both major and minor bleeding. There was no interaction between assigned GP IIb/IIIa inhibitor, creatinine clearance and ischemic outcome, major bleeding or minor bleeding.

CONCLUSIONS

Both ischemic and bleeding complications are highest in the lowest creatinine clearance quartile of patients treated with GP IIb/IIIa inhibitors. Although tirofiban is renally cleared and abciximab is not, there was no interaction between these GP IIb/IIIa inhibitors and creatinine clearance regarding ischemic or bleeding events.

Platelet glycoprotein IIb/IIIa inhibitors

Glycoprotein (GP) IIb/IIIa inhibitors including abciximab, eptifibatide and tirofiban have been studied extensively as short-term adjuncts to short-term heparin and indefinite aspirin in patients with acute coronary syndrome or undergoing percutaneous coronary interventions on native vessels. The drugs provide a small advantage in the composite endpoint of death, myocardial infarction, and need for revascularization at 30 days (1-2% of treated patients) at the expense of an increase in major and potentially fatal bleeding complications (1% of treated patients over heparin plus aspirin alone). Highest-risk patients appear to benefit the most; clopidogrel should also be considered in these patients. Patients undergoing percutaneous interventions on bypass grafts do not benefit. Whether one GP IIb/IIIa inhibitor is superior to another is incompletely clarified. Abciximab causes severe immune-mediated thrombocytopenia (<20,000/microl) in 0.7% of cases; this is more often than eptifibatide or tirofiban (0.2%). Pseudothrombocytopenia should be differentiated. Effective use of GP IIb/IIIa inhibitors for acute coronary syndrome and percutaneous coronary interventions requires discerning clinical judgment. The value of GP IIb/IIIa inhibitors is not established in other forms of vascular disease.

Triple antiplatelet therapy does not increase femoral access bleeding with vascular closure devices

BACKGROUND

The use of arteriotomy closure devices (CDs) to achieve hemostasis after femoral artery access in percutaneous coronary intervention is steadily increasing. However, the safety information with these devices in the era of triple antiplatelet therapy is limited.

METHODS

We reviewed prospectively collected data from the Do Tirofiban and ReoPro Give Similar Efficacy Outcomes Trial (TARGET), where all patients received aspirin, clopidogrel, and glycoprotein IIb/IIIa inhibitor therapy. At the treating physician's discretion, manual compression (MC) or a vascular hemostasis device was selected following femoral angiography. Patients receiving MC were to have sheaths removed 2 to 6 hours postprocedure when the activated clotting time was < or = 175 seconds.

RESULTS

Of 4809 patients, 4736 had femoral access, and 985 of these had a CD (Perclose 47%, Angio-Seal 43%, VasoSeal 5%, and other 5%). The MC and CD groups were similar regarding most demographic characteristics, including age, systolic blood pressure, and weight, but those with MC were more often female, diabetic, and had history of peripheral vascular disease. Patients with a CD had a lower ischemic event rate suggesting they were a lower risk cohort overall. There were no differences in major bleeding at the access site (0.4% vs 0.5%, P =.588), minor bleeding at the access site (1.9% vs. 3.1%, P =.142) or transfusions (0.8% vs 1.0%, P =.513) between the MC and CD groups, respectively.

CONCLUSIONS

In contemporary percutaneous coronary intervention practice, with appropriate patient selection, a CD can be safely utilized despite aggressive polypharmacy for procedural anticoagulation.

Triple antiplatelet therapy during percutaneous coronary intervention is associated with improved outcomes including one-year survival: results from the Do Tirofiban and ReoProGive Similar Efficacy Outcome Trial (TARGET)

OBJECTIVE

We sought to examine if clopidogrel treatment initiated before coronary stenting improved clinical outcomes among patients receiving aspirin and a glycoprotein (GP) IIb/IIIa inhibitor.

BACKGROUND

Antiplatelet therapy plays a pivotal role in contemporary percutaneous coronary interventions (PCI).

METHODS

Outcomes among 4,809 patients randomized to tirofiban or abciximab during PCI with stent placement were compared according to whether they received 300 mg of clopidogrel before PCI (93.1%) versus immediately after the procedure.

RESULTS

The 30-day primary composite end point (death, myocardial infarction [MI], or urgent target vessel revascularization [TVR]) was lower among clopidogrel-pretreated patients (6.6% vs. 10.4%, p = 0.009), mainly because of reduction of MI (6.0% vs. 9.5%, p = 0.012). The benefit of clopidogrel pretreatment was sustained at six months (death, MI, any TVR: 14.6% vs. 19.8%, HR = 0.71, p = 0.010), and this was due mainly to lowering of death and MI (7.8% vs. 13.0%, p = 0.001). At one year, clopidogrel pretreatment was associated with a lower mortality rate (1.7% vs. 3.6%, p = 0.011). Because clopidogrel pretreatment was not randomized, multivariable and propensity analyses were performed. After adjusting for baseline heterogeneity, clopidogrel pretreatment was an independent predictor for death or MI at 30 days (HR = 0.63, p = 0.012) and at six months (HR = 0.61, p = 0.003), and survival at one year (HR = 0.53, p = 0.044). No excess in 30-day bleeding events was noted with clopidogrel pretreatment.

CONCLUSIONS

Among patients undergoing coronary stent placement with aspirin and a GP IIb/IIIa inhibitor, clopidogrel pretreatment is associated with a reduction of death and MI irrespective of the type of GP IIb/IIIa inhibitor used.

Peripheral vascular disease and one-year mortality following percutaneous coronary revascularization

The association between peripheral vascular disease and outcomes after percutaneous coronary intervention was examined in the Do Tirofiban and Reopro Give Similar Efficacy Outcome Trial (TARGET). After adjustments in a multivariate model, a history of peripheral vascular disease was found to be associated with a two- to threefold increase in mortality at 1 year after coronary stent placement.

Angiographic variables predict increased riskfor adverse ischemic events after coronarystenting with glycoprotein IIb/IIIa inhibition

OBJECTIVES

We sought to assess whether pre-procedural angiographic characteristics are associated with adverse clinical outcomes after coronary stenting with glycoprotein IIb/IIIa inhibition.

BACKGROUND

Ischemic complications after balloon angioplasty are associated with pre- and post-procedural angiographic variables. However, in the current era of stenting with IIb/IIIa inhibition, it is unknown whether angiographic features assessed before intervention confer an increased risk of adverse procedural and subsequent clinical outcomes.

METHODS

In the Do Tirofiban and ReoPro Give Similar Efficacy Outcomes? Trial (TARGET), 4,809 patients undergoing planned stenting were randomized to tirofiban or abciximab. Baseline demographic, clinical, and angiographic variables were obtained. Clinical end points were recorded at 30 days and six months. The relationship between angiographic variables and adverse clinical outcomes was assessed.

RESULTS

Patients with the combination of thrombus, lesion eccentricity, and lesion length >20 mm had a 21.4% composite incidence of death, myocardial infarction, or urgent target vessel revascularization (TVR) at 30 days, compared with 4.2% in those patients without these high-risk features (hazard ratio [HR] 3.24, p < 0.001). After adjustment, the risk was independently associated with thrombus (HR 1.40, p = 0.034), eccentricity (HR 1.67, p < 0.001), and lesion length >20 mm (HR 1.89, p < 0.001). The risk of six-month TVR was independently associated with left anterior descending coronary artery lesions (HR 1.46, p < 0.001), restenotic lesions at baseline (HR 1.58, p = 0.006), and lesion length (HR 1.19, p = 0.03).

CONCLUSIONS

Patients with thrombus, eccentric lesions, or lesion length >20 mm are at high risk for ischemic outcomes after coronary stenting, despite IIb/IIIa inhibition. Further research into novel anti-thrombotic therapies or procedural strategies is necessary for these patients.

Effect of abciximab versus tirofiban on activated clotting time during percutaneous intervention and its relation to clinical outcomes--observations from the TARGET trial

Previous evidence suggests that the monoclonal antibody abciximab may have a more potent anticoagulant effect than small-molecule glycoprotein (GP) IIb/IIIa inhibitors. We prospectively reviewed collected heparin dose, activated clotting time (ACT), and corresponding clinical outcome data from The Do Tirofiban and ReoPro Give Similar Efficacy Outcome Trial (TARGET), a direct comparison of tirofiban versus abciximab in patients who underwent percutaneous intervention. Of the 4,809 patients enrolled in the trial, 3,739 patients (78%) had an ACT measured after the administration of GP IIb/IIIa and heparin (peak procedural ACT); this formed the population for the present study. Mean total heparin dose was 75 +/- 32 and 76 +/- 31 U/kg in the tirofiban and abciximab groups, respectively. The resultant mean peak ACTs were 296 +/- 91 and 299 +/- 89 seconds (p = 0.09). In a subset of patients with both baseline ACT (before any heparin or GP IIb/IIIa therapy) and peak procedural ACT measurements, the difference in ACT between these time points was 80 +/- 97 vs 82 +/- 101 seconds (p = 0.44) for the tirofiban and abciximab groups, respectively. After adjusting for patients' weight, weight-adjusted heparin dose, and method of ACT measurement in a multiple linear regression analysis, the type of GP IIb/IIIa inhibitor was not predictive of the peak ACT (p = 0.24). When stratified by ACT quartile, no statistically significant difference in bleeding or ischemic end points between the tirofiban and abciximab cohorts was observed. In this large contemporary percutaneous coronary intervention trial, there was no observed difference in the anticoagulant effect of tirofiban and abciximab, as measured by the ACT, or in the incidence of bleeding or ischemic complications in each ACT quartile.

Intravascular ultrasound-guided balloon angioplasty compared with stent: immediate and 6-month results of the multicenter, randomized Balloon Equivalent to Stent Study (BEST)

BACKGROUND

Balloon angioplasty guided by intravascular ultrasound (IVUS) makes it possible to choose the balloon size according to the true vessel diameter and to detect suboptimal results requiring subsequent stent implantation. The Balloon Equivalent to STent (BEST) study aimed to assess whether this strategy would give the same results as systematic stenting.

METHODS AND RESULTS

A total of 132 of 254 patients were randomized to IVUS-guided percutaneous transluminal coronary angioplasty (aggressive PTCA), and 122 were randomized to stenting (stent group). We hypothesized that a difference of <8% in the 6-month angiographic restenosis rate (primary end point) could be considered noninferior. The aggressive PTCA procedure was longer and had a greater use of contrast medium than stenting. In the aggressive PTCA group, crossover to stent was needed in 58 patients (44%). At 6 months, 20 of 119 patients (16.8+/-6.7%) in the aggressive PTCA group and 21 of 116 patients (18.1+/-7.0%) in the stent group had restenosis. The difference was -1.3%, with an upper limit of 95% confidence interval of 7.1% (ie, less than the noninferiority boundary). The in-stent restenosis rate was higher in the stent group (15.5% versus 5%; P=0.02). The differences in minimum lumen diameter, lumen cross-section area, and 1-year event rate were not significant.

CONCLUSIONS

A strategy of IVUS-guided angioplasty with provisional stenting is feasible and safe. At the cost of a more complex procedure, it reduces the stent rate by half, with similar 6-month angiographic IVUS and clinical outcome compared with stent implantation.

Utility of platelet adp receptor antagonism in the emergency department: a review

Emergency physicians are often the first clinicians to evaluate patients with acute atherothrombotic events. Platelet adenosine diphosphate (ADP) receptor antagonists, by specifically and irreversibly blocking ADP-induced platelet activation and aggregation, may reduce the injury associated with this process and can prevent recurrent ischemic events. Their role in the prevention of recurrent vascular events has been well documented. Recently, the CURE Trial showed that the combination of aspirin and clopidogrel improved outcomes in patients with non-ST-segment-elevation acute coronary syndrome (ACS). Familiarity with ADP receptor antagonists and knowledge about their appropriate use is important to the emergency physician in the management of ACS and potentially in that of transient ischemic attacks (TIAs), ischemic strokes, and acute peripheral arterial obstruction. This review addresses the pathophysiology of atherothrombosis and evaluates the potential use of ADP receptor antagonists in the Emergency Department setting.

Outcomes at 6 months for the direct comparison of tirofiban and abciximab during percutaneous coronary revascularisation with stent placement: the TARGET follow-up study

BACKGROUND

Two placebo-controlled trials testing intravenous platelet glycoprotein IIb/IIIa antagonists in the setting of percutaneous coronary revascularisation with intracoronary stents have shown a durable reduction in ischaemic events to 6 months. These trials differed regarding their patient population, IIb/IIIa inhibitor, and reported extent of benefit. Whether a small-molecule agent affecting only the IIb/IIIa receptor would provide a similar outcome for ischaemic events and clinical restenosis at 6 months when directly compared with a monoclonal antibody known to affect several integrin receptors is unknown.

METHODS

In 18 countries at 149 hospitals, 4809 patients undergoing elective or urgent stent implantation were randomly assigned a bolus and infusion of tirofiban or abciximab. Patients were followed for 6 months for the occurrence of death, myocardial infarction, and any target-vessel revascularisation. The results at 30 days have been reported previously.

FINDINGS

At 6 months the composite endpoint of death, myocardial infarction, and target-vessel revascularisation occurred in 356 (14.8%) patients who received tirofiban and 345 (14.3%) patients who received abciximab (hazard ratio 1.04, 95% CI 0.90-1.21; p=0.591). The rates for the individual endpoints were 191 (8.0%) versus 159 (6.6%) for myocardial infarction (hazard ratio 1.21, 95% CI 0.98-1.50; p=0.074), 26 (1.1%) versus 25 (1.0%) for death (1.04, 0.60-1.80; p=0.893), and 194 (8.1%) versus 208 (8.6%) for target-vessel revascularisation (0.93, 0.77-1.14; p=0.495).

INTERPRETATION

At 6 months, tirofiban provided a similar level of overall protection to abciximab against the composite of death, myocardial infarction, and any target-vessel revascularisation.

Impact of different platelet glycoprotein IIb/IIIa receptor inhibitors among diabetic patients undergoing percutaneous coronary intervention: : Do Tirofiban and ReoPro Give Similar Efficacy Outcomes Trial (TARGET) 1-year follow-up

BACKGROUND

The platelet glycoprotein IIb/IIIa receptor inhibitor abciximab, a monoclonal antibody, has been shown to improve early and late outcomes among diabetic patients undergoing percutaneous coronary intervention (PCI). It is unknown whether small-molecule agents confer similar benefits.

METHODS AND RESULTS

In 18 countries, 4809 patients undergoing PCI with stent implantation were randomized to tirofiban or abciximab. At the time of enrollment, patients were stratified according to diabetes status. As compared with non-diabetic patients, patients with diabetes (n=1117) showed similar 30-day ischemic outcomes, an increased incidence of any target vessel revascularization (TVR) at 6 months (10.3% versus 7.8%; P= 0.008), and a trend toward higher 1-year mortality (2.5% versus 1.6%; P=0.056). Among diabetic patients randomized to tirofiban (n=560), the incidence of death, myocardial infarction (MI), or urgent TVR at 30 days was 6.2%, and among those randomized to abciximab (n=557) it was 5.4% (hazard ratio [HR] 1.16; P=0.540). At 6 months, the composite of death, MI, or any TVR occurred in 15.7% and in 16.9% of tirofiban and abciximab patients, respectively (HR 0.93; P=0.610). Any TVR occurred in 9.5% and 11.1%, respectively (HR 0.84; P= 0.366). The 1-year mortality was 2.1% in the tirofiban group and 2.9% in the abciximab group (HR 0.74; P= 0.436).

CONCLUSIONS

Among diabetic patients undergoing PCI, tirofiban and abciximab were associated with comparable event rates, including similar rates of 6-month TVR and 1-year mortality. These findings suggest that the non-glycoprotein IIb/IIIa properties of abciximab do not translate into a discernible long-term clinical benefit among diabetic patients.

Impact of clinical syndrome acuity on the differential response to 2 glycoprotein IIb/IIIa inhibitors in patients undergoing coronary stenting: the TARGET Trial

BACKGROUND

Although glycoprotein IIb/IIIa inhibitors have been shown to reduce periprocedural and late ischemic events in patients undergoing stent implantation, the relative safety and efficacy of different agents in this class is less established. Also unknown is whether the acuity of the presenting clinical syndrome, which may affect the degree of platelet inhibition required or achieved, influences the response to different antiplatelet agents.

METHODS AND RESULTS

A prospective, multicenter, double-blind, randomized trial was performed in which 4809 patients undergoing planned stenting were randomized to receive abciximab or tirofiban. In patients with acute coronary syndromes (ACS; n=3025), abciximab resulted in lower rates of myocardial infarction at 30 days (5.8% versus 8.5%; P=0.004) and 6 months (7.2% versus 9.8%; P=0.013), although 6-month mortality rates were identical (1.39% in both groups; P=0.99). Conversely, in patients without ACS (n=1784), myocardial infarction rates were not significantly lower with tirofiban, survival was similar, and target vessel revascularization was reduced, which translated into a trend toward enhanced 6-month event-free survival with tirofiban (89.7% versus 86.6%; P=0.056).

CONCLUSIONS

In patients with ACS undergoing stent implantation, abciximab use compared with tirofiban results in greater suppression of periprocedural myonecrosis, although a survival benefit has not been demonstrated. Patients with stable coronary syndromes may have equivalent or better outcomes with tirofiban relative to abciximab, with fewer adverse hematologic and hemorrhagic events. These data raise important issues regarding the relative pharmacodynamic inhibition of platelet function required in varying clinical scenarios and have important implications for the cost-effective utilization of glycoprotein IIb/IIIa inhibitors.

Comparison of two platelet glycoprotein IIb/IIIa inhibitors, tirofiban and abciximab, for the prevention of ischemic events with percutaneous coronary revascularization

BACKGROUND

In the setting of percutaneous coronary revascularization, agents in the class known as platelet glycoprotein IIb/IIIa inhibitors have significantly reduced the incidence of death or nonfatal myocardial infarction at 30 days. We assessed whether there are differences in safety or efficacy between two such inhibitors, tirofiban and abciximab.

METHODS

Using a double-blind, double-dummy design at 149 hospitals in 18 countries, we randomly assigned patients to receive either tirofiban or abciximab before undergoing percutaneous coronary revascularization with the intent to perform stenting. The primary end point was a composite of death, nonfatal myocardial infarction, or urgent target-vessel revascularization at 30 days. The trial was designed and statistically powered to demonstrate the noninferiority of tirofiban as compared with abciximab.

RESULTS

The primary end point occurred more frequently among the 2398 patients in the tirofiban group than among the 2411 patients in the abciximab group (7.6 percent vs. 6.0 percent; hazard ratio, 1.26; one-sided 95 percent confidence interval of 1.51, demonstrating lack of equivalence, and two-sided 95 percent confidence interval of 1.01 to 1.57, demonstrating the superiority of abciximab over tirofiban; P=0.038). The magnitude and the direction of the effect were similar for each component of the composite end point (hazard ratio for death, 1.21; hazard ratio for myocardial infarction, 1.27; and hazard ratio for urgent target-vessel revascularization, 1.26), and the difference in the incidence of myocardial infarction between the tirofiban group and the abciximab group was significant (6.9 percent and 5.4 percent, respectively; P=0.04). The relative benefit of abciximab was consistent regardless of age, sex, the presence or absence of diabetes, or the presence or absence of pretreatment with clopidogrel. There were no significant differences in the rates of major bleeding complications or transfusions, but tirofiban was associated with a lower rate of minor bleeding episodes and thrombocytopenia.

CONCLUSIONS

Although the trial was intended to assess the noninferiority of tirofiban as compared with abciximab, the findings demonstrated that tirofiban offered less protection from major ischemic events than did abciximab.