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Antithrombotic Therapy During Percutaneous Coronary Intervention : The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy FREE TO VIEW

Jeffrey J. Popma, MD; Peter Berger, MD; E. Magnus Ohman, MD, FCCP; Robert A. Harrington, MD; Cindy Grines, MD; Jeffrey I. Weitz, MD
Author and Funding Information

Correspondence to: Jeffrey J. Popma, MD, Director, Interventional Cardiology, Brigham and Women’s Hospital, 75 Francis St, Tower 2–3A Room 311, Boston, MA 02115; e-mail: jpopma@partners.org

Chest. 2004;126(3_suppl):576S-599S. doi:10.1378/chest.126.3_suppl.576S
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This chapter about antithrombotic therapy during percutaneous coronary intervention (PCI) is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients’ values may lead to different choices (for a full understanding of the grading, see Guyatt et al, CHEST 2004;126:179S–187S). Among the key recommendations in this chapter are the following: For patients undergoing PCI, we recommend pretreatment with aspirin, 75 to 325 mg (Grade 1A). For long-term treatment after PCI, we recommend aspirin, 75 to 162 mg/d (Grade 1A). For long-term treatment after PCI in patients who receive antithrombotic agents such as clopidogrel or warfarin, we recommend lower-dose aspirin, 75 to 100 mg/d (Grade 1C+). For patients who undergo stent placement, we recommend the combination of aspirin and a thienopyridine derivative (ticlopidine or clopidogrel) over systemic anticoagulation therapy (Grade 1A). We recommend clopidogrel over ticlopidine (Grade 1A). For all patients undergoing PCI, particularly those undergoing primary PCI, or those with refractory unstable angina or other high-risk features, we recommend use of a glycoprotein (GP) IIb-IIIa antagonist (abciximab or eptifibatide) [Grade 1A]. In patients undergoing PCI for ST-segment elevation MI, we recommend abciximab over eptifibatide (Grade 1B). In patients undergoing PCI, we recommend against the use of tirofiban as an alternative to abciximab (Grade 1A). In patients after uncomplicated PCI, we recommend against routine postprocedural infusion of heparin (Grade 1A). For patients undergoing PCI who are not treated with a GP IIb-IIIa antagonist, we recommend bivalirudin over heparin during PCI (Grade 1A). In PCI patients who are at low risk for complications, we recommend bivalirudin as an alternative to heparin as an adjunct to GP IIb-IIIa antagonists (Grade 1B). In PCI patients who are at high risk for bleeding, we recommend that bivalirudin over heparin as an adjunct to GP IIb-IIIa antagonists (Grade 1B). In patients who undergo PCI with no other indication for systemic anticoagulation therapy, we recommend against routine use of vitamin K antagonists after PCI (Grade 1A).

The use of percutaneous coronary intervention (PCI) as an alternative to coronary artery bypass graft surgery (CABG) in patients with ischemic heart disease has expanded dramatically over the past 2 decades. In the United States, it is estimated that PCI was performed in > 900,000 patients in 2003, exceeding the number of patients undergoing CABG. The procedural success, safety, and durability of PCI have improved dramatically since its introduction, reflecting continual technological improvements (eg, drug-eluting stents, distal protection devices), refinements in periprocedural adjunctive pharmacology (eg, glycoprotein [GP] IIb-IIIa inhibitors, alternative thrombin inhibitors), and a better understanding of patient and lesion selection criteria and their relationship to early and late clinical outcomes.

Initially, antithrombotic agents were evaluated based on their capacity to reduce the major ischemic complications associated with balloon angioplasty, including periprocedural death (0 to 1.7%), myocardial infarction (MI) [1.3 to 8.6%], vessel occlusion (immediate or delayed) [6.8 to 8.3%], and the need for early (< 30 days) emergent CABG surgery (1.3 to 3.6%) or repeat PCI (4.5%).15 These complications were caused by arterial thrombus formation at the site of vessel injury, a complication that occurred alone or in association with coronary artery dissection. The introduction of coronary stents reduced the risk of acute complications, thereby lowering the need for emergency CABG surgery to < 1%,67 and reducing the rate of recurrent symptoms due to restenosis. With the availability of new drug-eluting stents, late recurrence rates of < 4% have been reported.8 Because of these results, coronary stents are now used in > 90% of patients undergoing PCI.

Appropriate use of antiplatelet agents (eg, aspirin, clopidogrel, and GP IIb-IIIa inhibitors) and anticoagulants (eg, IV heparin, low molecular weight heparin [LMWH], or bivalirudin) during PCI is aimed at improving early (30-day) clinical outcome, and focuses on preventing complications at the site of intervention. In contrast, extended therapy with antiplatelet drugs may reduce the frequency of thrombotic complications at remote sites. None of the antithrombotic regimens tested to date have had a significant effect on restenosis. In this chapter, the evidence supporting the use of antithrombotic agents in the PCI setting is reviewed and recommendations are provided. Table 1 lists the question definition and eligibility criteria for the studies considered in this review.

1.1 Aspirin

Aspirin irreversibly inhibits cyclooxygenase, thereby blocking platelet synthesis of thromboxane A2, a humeral mediator that promotes platelet aggregation. Initial studies evaluating aspirin in the PCI setting were designed to determine whether aspirin prevented restenosis. Although aspirin had no impact on this end point, these studies also provided information on the effect of aspirin on short-term ischemic complications.910 Many of these early studies used aspirin in conjunction with other antiplatelet drugs, such as dipyridamole or ticlopidine.1011 Nonetheless, these early trials set the stage for aspirin as part of the foundation of antiplatelet drugs used in PCI. Furthermore, because aspirin reduces cardiovascular death, MI, and stroke in patients with coronary artery disease, most patients are administered this medication.

The studies supporting the use of aspirin in PCI are reviewed in Table 2 . In a study of 376 patients randomly assigned to receive aspirin (990 mg/d) plus dipyridamole (225 mg/d) or placebo starting 24 h before angioplasty and continued for 4 to 7 months after the procedure, the frequency of periprocedural MI was significantly lower with combined antiplatelet therapy than with placebo (1.6% and 6.9%, respectively; p = 0.011).9 A second study that has not been published randomized 333 patients undergoing balloon angioplasty to one of three treatment arms; the combination of aspirin (650 mg/d) plus dipyridamole (225 mg/d), to ticlopidine (750 mg/d) or to placebo before the procedure. Immediate procedural complications, such as abrupt occlusion, thrombosis, or major dissection, occurred in 7% of the patients; complications were less frequent in patients treated with aspirin plus dipyridamole or ticlopidine (5% and 2%, respectively) than in those receiving placebo (14%; p < 0.005).9The beneficial effect of aspirin plus dipyridamole in reducing ischemic complications was also documented in a retrospective study10 that included 300 patients undergoing coronary angioplasty. Stepwise logistic regression demonstrated that the lack of antiplatelet therapy at the time of coronary angioplasty was the most important predictor for the development of angiographically and clinically significant periprocedural thrombosis.10

Aspirin alone has been compared with aspirin plus dipyridamole in patients undergoing elective balloon angioplasty. Lembo and colleagues11 randomized 232 patients to either aspirin (325 mg/d) or the same dose of aspirin plus dipyridamole (225 mg/d). Rates of periprocedural MI were 1.7% and 4.3%, respectively, in the two treatment groups (p = not significant [NS]). Thus, this study failed to demonstrate a benefit of dipyridamole addition to aspirin.

1.1.1 Aspirin dose

Aspirin exerts its inhibitory effect within 60 min of oral administration, and its effect on platelet inhibition lasts for up to 7 days after the last dose of aspirin.12The minimum effective aspirin dosage in the setting of PCI has not been established. In an unpublished randomized trial,13 495 patients were randomly assigned to low-dose (80 mg/d) or high-dose (1,500 mg/d) aspirin starting 24 h before balloon angioplasty. There were no differences between the two groups with respect to the occurrence of MI (3.6% vs 3.9%, respectively) or need for CABG surgery (3.6% vs 3.7%, respectively) [Table 2]. Because the GI side effects of aspirin are dose related, an empiric dose of aspirin of 75 to 325 mg is administered at least 2 h prior to the procedure. A longer pretreatment period (up to 24 h) should be considered if a lower dose of aspirin (75 to 100 mg) is used because of the potential delay in bioavailability and attainment of a platelet inhibitory effect.

1.1.2 Effect of aspirin on restenosis

Studies9,1416 evaluating the effect of aspirin on the prevention of restenosis after balloon angioplasty have provided conflicting results, likely attributable to the varied dosage, timing, and duration of aspirin therapy, small sample sizes, and incomplete angiographic follow-up (Table 3 ). Overall, however, there is no evidence that aspirin influences the rate of restenosis. For example, in one trial,,9 376 patients were randomized to treatment with the combination of aspirin (990 mg/d) and dipyridamole (75 mg/d) or with placebo for 6 months after balloon angioplasty. There was no difference in the rate of binary restenosis in the two treatment groups (37.7% and 38.6%, respectively).9 A smaller randomized study16assigned 212 patients to 6 months of treatment with aspirin (100 mg/d) or placebo within 2 weeks of successful angioplasty. Angiographic restenosis occurred in 25% of aspirin-treated patients and in 38% of those receiving placebo (p < 0.025). However, there were no significant differences in clinical outcomes between the two groups. Although these trials suggest that aspirin has little or no effect on angiographic or clinical restenosis, long-term aspirin therapy is useful for secondary prevention of cardiovascular events (ie, death, MI, or stroke).17

1.1.3 Dose of aspirin when administered in combination with other antithrombotic drugs

When aspirin is administered in combination with other antiplatelet agents or with anticoagulants, it is reasonable to use a daily dose of 75 to 162 mg, rather than 325 mg, to minimize bleeding complications. Although there are no randomized trials comparing 75 to 162 mg with 325 mg of aspirin, the concept is supported by a post hoc analysis of data from the Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) study.18 For this analysis, patients were classified into three aspirin dose groups: < 100 mg, 101 to 199 mg, and ≥ 200 mg.18 The combined incidence of cardiovascular death, MI, or stroke was reduced by clopidogrel regardless of aspirin dose, but the incidence of major bleeding increased as a function of the aspirin dose, both in patients receiving aspirin plus placebo (1.9%, 2.8%, and 3.7%, respectively; p = 0.0001) and in those receiving aspirin plus clopidogrel (3.0%, 3.4%, and 4.9%, respectively; p = 0.0009).18

1.1.1. For patients undergoing PCI, we recommend pretreatment with aspirin, 75 to 325 mg (Grade 1A).

1.1.2. For long-term treatment after PCI, we recommend aspirin, 75 to 162 mg/d (Grade 1A).

1.1.3. For long-term treatment after PCI in patients who receive antithrombotic agents such as clopidogrel or warfarin, we recommend lower-dose aspirin, 75 to 100 mg/d (Grade 1C+).

1.2 Thienopyridine derivatives

Thienopyridine derivatives produce irreversible inhibition of the platelet adenosine diphosphate receptor, thereby attenuating platelet aggregation in response to adenosine diphosphate released from activated platelets.1920 Aspirin and thienopyridines derivatives have complementary mechanisms of action, and the combination of these agents inhibits platelet aggregation to a greater extent than either agent alone.21Combined antiplatelet therapy with aspirin and a thienopyridine is superior to systemic anticoagulation therapy for prevention of complications after coronary stent insertion. Thus, subacute vessel closure, which occurred 2 to 14 days after stent placement, was reported in 3 to 5% of cases in the initial series, despite the use of an aggressive antithrombotic regimen that included aspirin, dipyridamole, dextran, and IV heparin overlapping with a vitamin K antagonist. The risk of acute complications is reduced with aspirin plus a thienopyridine.2223 Thus, in a randomized trial24 that included 517 high-risk patients treated with Palmaz-Schatz stents (Cordis Corporation, Warren, NJ) for acute MI, suboptimal angioplasty, or other “high-risk” clinical and anatomic features, patients were assigned to antiplatelet therapy (aspirin plus ticlopidine) or anticoagulant therapy (aspirin, heparin, and a vitamin K antagonist) after successful stent placement. The primary end point, a composite of cardiovascular death, MI, CABG surgery, or repeat angioplasty, occurred in 1.5% of patients receiving antiplatelet therapy and 6.2% of those randomized to anticoagulant treatment (p = 0.01).24Subacute stent thrombosis occurred in 0.8% of patients in the antiplatelet therapy group and in 5.4% of those receiving anticoagulants. The Stent Anti-thrombotic Regimen Study25 randomized 1,653 lower-risk patients to aspirin alone (325 mg/d), the combination of aspirin (325 mg/d) plus ticlopidine (500 mg/d) for 1 month, or to aspirin (325 mg/d) plus warfarin after successful placement of a Palmaz-Schatz stent.25 The composite of death, target lesion revascularization, angiographic thrombosis, or MI at 30 days was reduced from 3.6% in patients assigned to aspirin alone and 2.7% in those assigned to aspirin plus warfarin to 0.5% in those receiving the combination of aspirin and ticlopidine (p < 0.001).25 Thus, based on these studies, the combination of aspirin plus a thienopyridine has become the standard of care.

Patients with a compelling need for coronary stenting who have contraindications to thienopyridine derivatives or who require a truncated course of thienopyridine therapy may benefit from heparin-, phosphorylcholine-, or carbon-coated stents because thrombosis rates appear to be low with these types of stents, even if patients are treated only with aspirin.2627 Thus, in a multicenter, prospective, nonrandomized, pilot study,26 200 patients were treated with aspirin alone after insertion of a heparin-coated stent.26 The primary end point, stent thrombosis at 30 days, occurred in only 2 of 200 patients (1%).

1.2.1 Ticlopidine vs clopidogrel

Side effects are common with ticlopidine, and the drug can cause neutropenia and thrombocytopenia. Clopidogrel is safer than ticlopidine and easier to administer. Thus, clopidogrel does not cause neutropenia, thereby obviating the need for blood count monitoring (Table 4 ). Furthermore, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura are rare complications of clopidogrel.2829 Finally, unlike ticlopidine, which requires twice-daily administration, clopidogrel can be administered once daily.3032

In two randomized trials,3334 clopidogrel and ticlopidine had similar efficacy, but clopidogrel produced fewer side effects. The Clopidogrel Aspirin Stent International Cooperative Study53 randomized 1,020 patients to clopidogrel (300-mg loading dose followed by 75 mg/d) plus aspirin (325 mg/d) or clopidogrel (75 mg/d without a loading dose) and aspirin, or to ticlopidine (500 mg/d) and aspirin. The primary end point, a composite of major bleeding complications, neutropenia, thrombocytopenia, or early discontinuation of study drug, occurred in 9.1% of patients in the ticlopidine group and 4.6% of patients in the combined clopidogrel groups (relative risk, 0.50; p = 0.005).33 Overall rates of major adverse cardiac events (cardiac death, MI, target lesion revascularization) were low and comparable between treatment groups (0.9% with ticlopidine, and 1.5% and 1.2% with clopidogrel, without or with a loading dose; p = NS for all comparisons).33In another study,34700 patients were randomly assigned to receive a 4-week course of either ticlopidine (500 mg/d) or clopidogrel (75 mg/d) in addition to aspirin (100 mg/d). The prespecified primary cardiac end point, a composite of cardiac death, urgent target vessel revascularization (TVR), angiographically documented occlusion, or nonfatal MI within 30 days, occurred in 3.1% of patients assigned to clopidogrel and in 1.7% of those receiving ticlopidine (p = 0.24). Side effects were significantly less frequent in patients receiving clopidogrel than in those assigned to ticlopidine (4.5% and 9.6%, respectively; p = 0.01). A meta-analysis35of these trials showed that compared with ticlopidine, clopidogrel was associated with a significant reduction in the incidence of major adverse cardiac events (odds ratio [OR], 0.50; p = 0.001) and mortality (OR, 0.43; p = 0.001). If ticlopidine is administered after stent placement, it is reasonable to restrict its use to 14 days so as to minimize the risk of hematologic toxicity. In one large study36 that evaluated a 14-day course of ticlopidine, the frequency of ischemic events was 0.73%; only 0.27% of patients had possible stent thrombosis between day 15 and day 30 (95% confidence interval [CI], 0.06 to 0.77).

Although the majority of subacute thrombotic events occur within the first 24 h after stent placement in patients treated with aspirin and a thienopyridine derivative,37it is reasonable to delay nonemergent, noncardiac surgery for 6 weeks after stent placement.38 Thus, in a series38 of 207 patients who underwent surgery shortly after successful coronary stent placement, 4.0% died, suffered an MI, or acquired stent thrombosis. All patients with complications underwent surgery within 6 weeks after stent placement. No events occurred in the remaining patients who underwent surgery between 7 weeks and 9 weeks after stent placement.38 There are no studies evaluating morbidity and mortality associated with noncardiac surgery after placement of drug-eluting stents.

1.2.2 Pretreatment with thienopyridines prior to PCI

Most randomized trials demonstrating the benefit of ticlopidine or clopidogrel started the drug immediately after PCI was completed. In PCI-CURE,39pretreatment with clopidogrel for up to 10 days prior to PCI in patients with acute coronary syndromes resulted in improved 30-day outcomes compared with no clopidogrel pretreatment. An overall beneficial effect of pretreatment with clopidogrel could not be demonstrated in patients undergoing elective stent placement. In a subset analysis of the Clopidogrel for the Reduction of Events During Observation (CREDO) trial40(described below), however, patients pretreated with clopidogrel at least 6 h prior to PCI experienced a 38.6% relative reduction in the combined end point of death, MI, or TVR compared with those who did not receive clopidogrel pretreatment (p = 0.01). Additional analysis of the CREDO trial has suggested that the benefit of pretreatment may be limited to those patients who received pretreatment > 15 h prior to PCI.41

The platelet inhibitory effects of thienopyridines are delayed after drug administration, but can be achieved more rapidly by giving a loading dose. Thus, higher doses of clopidogrel (450 to 600 mg) prior to PCI may provide additional benefit compared with the conventional 300-mg loading dose.42A recent randomized trial43 demonstrated that after a 600-mg loading dose of clopidogrel administered > 2 h prior to PCI, patients treated with high-dose heparin (140 IU/kg) had outcomes similar to those in patients treated with abciximab and lower-dose heparin (70 IU/kg). However, more information is needed before a high-dose clopidogrel loading regimen can be recommended on a routine basis. Furthermore, the potential beneficial effect of pretreatment must be balanced against the increased risk of bleeding with clopidogrel should emergency CABG surgery be needed because of unfavorable anatomy or a PCI-induced complication.

1.2.3 Aspirin-intolerant patients

Hypersensitivity to aspirin can be manifested as acute asthma, urticaria, angioedema or, less commonly, as a systemic anaphylactoid reaction.44 Although rapid oral challenge-desensitization to aspirin can be safely performed after PCI,4445 aspirin desensitization provides little protection for the reduction of events during PCI. In aspirin-intolerant patients, thienopyridine derivatives or GP IIb-IIIa inhibitors can be substituted for aspirin prior to PCI. An unpublished, randomized trial assigned 333 patients to treatment with either placebo, a combination of aspirin (650 mg/d) plus dipyridamole (225 mg/d), or ticlopidine (750 mg/d) before balloon angioplasty.46 Immediate procedure-related complications (abrupt occlusion, thrombosis, or major dissection) occurred in 23 of the 333 patients (7%); complications were less frequent with aspirin plus dipyridamole and ticlopidine than they were with placebo (5%, 2%, and 14%, respectively; p < 0.005).46

1.2.4 Duration of thienopyridine therapy after stent placement

Extended treatment with the combination of aspirin and clopidogrel after PCI for an acute coronary syndrome39or after elective angioplasty40 appears to reduce the rate of ischemic events (Table 5 ). The CREDO trial,39 was a randomized, blinded, placebo-controlled trial conducted in 2,116 patients undergoing elective PCI. Patients were randomly assigned to receive a 300-mg clopidogrel loading dose or placebo 3 to 24 h before PCI. Thereafter, all patients received clopidogrel (75 mg/d) until day 28.39From day 29 through 12 months, patients in the loading-dose group received clopidogrel (75 mg/d), while those in the control group received placebo. Both groups received aspirin throughout the study. The 12-month incidence of the composite of death, MI, or stroke in the intent-to-treat population was reduced by 26.9% in patients treated with long-term clopidogrel (p = 0.02).40 A limitation of this study is that patients assigned to no pretreatment were not administered a loading dose of clopidogrel after the procedure.

Compared with aspirin alone, there was an excess of minor and major bleeding with the combination of aspirin and clopidogrel in patients with non–ST-segment elevation MI (NSTEMI) in the CURE trial (Table 6 ), although the incidence of life-threatening bleeding was not different between the two groups.47 Using the Thrombolysis in Myocardial Infarction (TIMI) criteria for major bleeding, the rate of major bleeding with the combination of aspirin plus clopidogrel were similar to that with aspirin alone (1.1% and 1.2%, respectively; p = 0.70).47 Major or life-threatening bleeding in the PCI-CURE study39was similar in the two groups, even in patients who received a GP IIb-IIIa inhibitor. In the CREDO trial,40 major bleeding as defined by the TIMI criteria tended to be higher in the clopidogrel group than in those receiving placebo (8.8 and 6.7%, respectively; p = 0.07), although most of the major bleeding episodes were related to invasive procedure, such as CABG. Minor bleeding episodes were significantly more common with combination antiplatelet therapy in both the CURE and PCI-CURE studies. The CREDO trial40 did not find differences in minor bleeding between the two groups. It is possible that the incidence of bleeding complications can be reduced if lower doses of aspirin are used in combination with clopidogrel.40

Three randomized trials8,4849 have shown a marked (70 to 80%) reduction in clinical events with the use of sirolimus-eluting stents. Because of the potential for delayed endothelialization of these devices, the combination of aspirin and a thienopyridine derivative, most often clopidogrel, was administered for 2 months8 or 3 months49after the procedure. Subacute stent thrombosis was an uncommon event (< 1%) in these studies. Likewise, with the combination of aspirin plus a thienopyridine for 6 months, clinical events after stenting were reduced by 70% with paclitaxel-eluting stents. Rates of subacute stent thrombosis were similar with drug-eluting and bare metal stents with 6 months of dual antiplatelet therapy with aspirin and clopidogrel.5051 Because of cost and risk of potential bleeding complications, some clinicians prefer a shorter course of treatment with clopidogrel after PCI, particularly in patients with an isolated coronary artery lesion or with a low atherosclerotic risk.

1.2.1. Ticlopidine versus clopidogrel after stent placement For patients who undergo stent placement, we recommend the combination of aspirin and a thienopyridine derivative (ticlopidine or clopidogrel) over systemic anticoagulation therapy (Grade 1A). We recommend clopidogrel over ticlopidine (Grade 1A). We recommend a loading dose of 300 mg of clopidogrel at least 6 h prior to planned PCI (Grade 1B). If clopidogrel is started < 6 h prior to planned PCI, we suggest a 600-mg loading dose of clopidogrel (Grade 2C). If ticlopidine is administered, we recommend that a loading dose of 500 mg at least 6 h before planned PCI (Grade 2C).

1.2.3 Aspirin intolerant patients For PCI patients who cannot tolerate aspirin, we recommend that the loading dose of clopidogrel (300 mg) or ticlopidine (500 mg) be administered at least 24 h prior to planned PCI (Grade 2C).

1.2.4 Duration of thienopyridine therapy after stent placement After PCI, we recommend, in addition to aspirin, clopidogrel (75 mg/d) for at least 9 to 12 months (Grade 1A). If ticlopidine is used in place of clopidogrel after PCI, we recommend ticlopidine for 2 weeks after placement of a bare metal stent in addition to aspirin (Grade 1B). In patients with low atherosclerotic risk such as those with isolated coronary lesions, we recommend clopidogrel for at least 2 weeks after placement of a bare metal stent (Grade 1A), for 2 to 3 months after placement of a sirolimus-eluting stent (Grade 1C+), and 6 months after placement of a paclitaxel-eluting stent (Grade 1C).

1.3 Other oral antiplatelet agents

Cilostazol, which selectively inhibits 3′5′-cyclic nucleotide phosphodiesterase III, has antiplatelet and vasodilating effects. In addition, this agent also inhibits vascular smooth-muscle cell proliferation in vitro.52Early studies with cilostazol suggested that this agent could be used as an alternative to ticlopidine in patients undergoing stent implantation,53but the capacity of cilostazol to prevent subacute thrombosis in patients with drug-eluting stents has been questioned.54

Five studies52,5557 have evaluated cilostazol for prevention of restenosis after coronary stenting (Table 7 ), and have yielded conflicting results. Although initial small studies suggested that cilostazol reduces restenosis,,52,5557 the largest study53 failed to demonstrate a benefit of cilostazol. This study53 randomized 409 patients undergoing elective stent placement to receive aspirin plus ticlopidine or aspirin plus cilostazol starting 2 days before stenting. The angiographic restenosis rate was 27% in patients treated with aspirin and ticlopidine, and 22.9% in those receiving aspirin and cilostazol (p = NS).53 The Cilostazol for Restenosis Trial (CREST) is an ongoing evaluation of 705 patients undergoing elective treatment with stent implantation. Patients are randomized to either aspirin and clopidogrel or to aspirin, clopidogrel, and cilostazol 100 mg twice daily for 6 mo. Preliminary results from this larger study found an approximately 30% reduction in angiographic restenosis associated with the long-term use of cilostazol (William Weintraub, MD; Emory University, Atlanta, GA; personal communication, November 2003).

The addition of dipyridamole to aspirin provides little incremental benefit over aspirin alone for the prevention of early complications after coronary angioplasty. In a study11 of 232 patients randomly assigned to aspirin alone (975 mg/d) or the combination of aspirin (975 mg/d) plus dipyridamole (225 mg/d) before coronary angioplasty, there were no differences in the frequency of Q-wave MI (1.7% vs 4.3%, respectively) or in the need for emergency CABG surgery (2.6% vs 6.1%, respectively). Other antiplatelet agents, such as prostacyclin, ketanserin, sarpogrelate, and sulotroban, have had little or no effect on the prevention of acute complications58or restenosis5965 after PCI.

1.3.1. For patients after stent placement, we suggest ticlopidine (Grade 1B) or clopidogrel (Grade 1C) over cilostazol.

1.3.2. In aspirin-intolerant patients undergoing PCI, we suggest clinicians do not use dipyridamole as an alternative to a thienopyridine derivative (Grade 2C).

Ligation of fibrinogen by platelet GP IIb-IIIa receptors and, under high shear conditions, von Willebrand factor, serves as the “final common pathway” of platelet aggregation by bridging adjacent platelets together. Three IV inhibitors of the GP IIb-IIIa receptor are licensed in North America, and these agents produce a 35 to 50% reduction in clinical events in patients with acute coronary syndromes (Table 8 ). These agents include abciximab, eptifibatide and tirofiban.


Abciximab was first studied in the Evaluation of 7E3 for the Prevention of Ischemic Complications Trial,2 which included 2,099 high-risk patients undergoing PCI. All patients received aspirin (325 mg) and a nonweight-adjusted heparin bolus (10,000 to 12,000 IU) prior to PCI. Patients were then randomly assigned to treatment with placebo, a bolus of abciximab (0.25 mg/kg), or the same bolus dose of abciximab followed by a 12-h abciximab infusion (10 μg/min). Compared with placebo, bolus plus infusion abciximab was associated with a 35% reduction in frequency of the end point, a composite of death, nonfatal MI, need for repeat revascularization, or procedural failure (12.8% and 8.3%, respectively; p = 0.008).2 However, major bleeding complications were twice as frequent in patients receiving abciximab, reflecting the high-dose of heparin that was administered in this study.

The Evaluation of PTCA to Improve Long-Term Outcome by Abciximab GP IIb-IIIa Blockade (EPILOG) trial66 included 2,792 low-risk patients undergoing PCI. All patients in the EPILOG trail received aspirin and were then randomized to weight-adjusted heparin (100 IU/kg with target activated clotting time [ACT] of 300 s) plus placebo; the same heparin dose plus abciximab; or lower-dose heparin (70 IU/kg with minimum ACT target of 200 s) plus abciximab. Compared with placebo, the 30-day end point, a composite of death, MI, or urgent revascularization, was significantly lower in patients treated with abciximab plus lower-dose or usual-dose heparin (11.7%, 5.2%, and 5.4%, respectively; p < 0.001).66 The need for transfusion was 3.9% in patients receiving the usual heparin dose plus placebo, whereas it was 3.3% and 1.9% in the abciximab-treated patients receiving usual-dose or low-dose heparin, respectively. Based on these results, the use of a lower-dose heparin regimen became the standard of care.

The Evaluation of Platelet IIb-IIIa Inhibitor for Stenting (EPISTENT) trial67 randomly assigned 2,399 patients with ischemic coronary artery disease to stenting plus placebo, stenting plus abciximab, or balloon angioplasty plus abciximab. The primary 30-day end point, a combination of death, MI, or need for urgent revascularization, occurred in 10.8% of patients in the stent plus placebo group, 5.3% of those in the stent-plus-abciximab group (hazard ratio, 0.48; p < 0.001), and 6.9% in the group undergoing balloon PTCA and receiving abciximab (hazard ratio, 0.63; p = 0.007). No significant differences in bleeding complications were noted among the various treatment groups.

The effect of periprocedural abciximab on the prevention of late restenosis has been controversial. Although the Evaluation of 7E3 for the Prevention of Ischemic Complications study68showed a 23% reduction in cumulative 6-month clinical events (p = 0.001), these events were primarily related to the prevention of early (< 30-day) periprocedural events. A subgroup of diabetic patients undergoing stent implantation in EPISTENT trial69showed a reduction in 6-month TVR, from 16.6% in those receiving placebo to 8.1% in those receiving abciximab; but a larger study70 of 1,117 diabetics undergoing stent placement and treatment with either tirofiban or abciximab failed to confirm a beneficial effect of GP IIb-IIIa inhibitors on the incidence of late restenosis. In this trial,70 TVR occurred in 9.5% of patients treated with tirofiban and 11.1% of patients treated with abciximab (p = 0.366). Thus, the major benefit of GP IIb-IIIa inhibitors appears to be a reduction of acute ischemic events associated with PCI; these agents do not appear to influence vascular remodeling or restenosis.

Abciximab does not reduce complication rates associated with saphenous venous graft interventions.71Although “bailout” abciximab is often administered during or just after PCI if there is residual dissection, thrombus, or suboptimal results,72 this approach has not been evaluated in prospective studies.

Late mortality benefits have been reported after use of abciximab.73 In a meta-analysis73 of 12 trials that enrolled 20,186 patients, 30-day mortality was significantly reduced with GP IIb-IIIa inhibition (OR, 0.73; 95% CI, 0.55 to 0.96; p = 0.024). Although 10 of the 12 trials showed a beneficial effect of GP IIb-IIIa inhibitor treatment on mortality, no individual trial detected a statistically significant mortality benefit.73 At 6 months, the OR was 0.84 (95% CI, 0.69 to 1.03; p = 0.087).73 This survival benefit amounts to a saving of 3.2 lives after 6 months per 1,000 patients treated (number needed to treat, 313).73


The Integrilin to Minimize Platelet Aggregation and Coronary Thrombosis (IMPACT)-II trial74 enrolled 4010 patients undergoing PCI. Patients were randomized to treatment with placebo, a low-dose bolus of eptifibatide (135 μg/kg) followed by a low-dose infusion (0.5 μg/kg/min for 20 to 24 h), or the same eptifibatide bolus and a slightly higher-dose infusion (0.75 μg/kg/min for 20 to 24 h). In IMPACT-II,74 the primary end point, a 30-day composite of death, MI, unplanned CABG surgery or repeat PCI, or coronary stenting for abrupt closure, occurred in 11.4% of patients in the placebo group compared with 9.2% in the 135/0.5 eptifibatide group (p = 0.063) and 9.9% in the eptifibatide 135/0.75 group (p = 0.22).74 Eptifibatide treatment did not increase rates of major bleeding or transfusion.

It is now recognized that the eptifibatide dose used in the IMPACT-II trial was insufficient to provide adequate platelet GP IIb-IIIa inhibition during PCI. The Enhanced Suppression of the Platelet IIb/IIIa Receptor With Integrilin Therapy (ESPRIT) trial75 evaluated a higher-dose, double-bolus, eptifibatide regimen (two 180 μg/kg boluses administered 10 min apart, followed by an infusion of 2.0 μg/kg/min for 18 to 24 h) vs placebo in a randomized study of 2,064 patients undergoing stent implantation in a native coronary artery. The primary end point, a composite of death, MI, urgent TVR, or bailout GP IIb/IIIa inhibitor therapy within 48 h of randomization, occurred in 10.5% of 1,024 patients receiving placebo and in 6.6% of those treated with eptifibatide (p = 0.0015). The key 30-day secondary end point was also reduced, from 10.5% to 6.8% (p = 0.0034). These effects were sustained 1 year after the procedure, and eptifibatide also was effective in the subgroup of high-risk diabetic patients.63 Major bleeding was infrequent, but occurred more frequently with eptifibatide than with placebo (1.3% and 0.4%, respectively; p = 0.027).7576 Based on the results of this trial, the eptifibatide regimen used in the ESPRIT trial has become the standard of care with this agent.