Bivalirudin vs Heparin in Percutaneous Coronary Intervention: A Pooled Analysis

Safety of routine protamine in the reversal of heparin in percutaneous coronary intervention: A systematic review and meta-analysis

OBJECTIVES

To determine the safety and efficacy of protamine in the reversal of heparin in percutaneous coronary intervention (PCI).

BACKGROUND

Heparin is routinely used for anticoagulation in PCI. Protamine is not used routinely to reverse heparin's effects in PCI, partly due to the perceived risk of stent thrombosis.

METHODS

Relevant studies published in English were searched for in PubMed, Embase, and Cochrane databases from inception to April 26th, 2023. Our primary outcome of interest was stent thrombosis in patients receiving PCI for all indications. Secondary outcomes included mortality, major bleeding complications, and hospitalization length. Dichotomous outcomes were analyzed using a Mantel-Haenszel random-effects model and expressed as odds ratios (OR) with their 95% confidence intervals (CI), while continuous outcomes were analyzed using an inverse variance random-effects model expressed as mean differences (MD) with their 95% CI.

RESULTS

11 studies were included in our analysis. Protamine use was not associated with stent thrombosis: OR 0.58, 95% CI: 0.33, 1.01 (p = 0.05) nor with mortality (p = 0.89). Protamine administration was associated with a decreased incidence of major bleeding complications: OR 0.48; 95% CI: 0.25, 0.95 (p = 0.03) and decreased length of hospitalization (p < 0.0001).

CONCLUSIONS

In patients pre-treated with dual antiplatelet therapy (DAPT), protamine may be a safe and efficacious option to facilitate earlier sheath removal, reduce major bleeding complications, and reduce length of hospitalization without increased risk of stent thrombosis.

Efficacy and safety of bivalirudin in coronary artery disease patients with mild to moderate chronic kidney disease: Meta-analysis

BACKGROUND

Patients with chronic kidney disease (CKD) have elevated bleeding and ischemic outcomes. We aim to assess the short- and long-term efficacy and safety of bivalirudin compared to heparin plus glycoprotein IIb/IIIa inhibitors (GPIs) in coronary artery disease (CAD) patients with CKD.

METHODS

Randomized trials were searched in PubMed, Cochrane, and Embase databases up to January 2017. Among the trials retrieved, efficacy endpoints were defined as mortality, myocardial infarction (MI), repeat revascularization, stent thrombosis, and major adverse cardiac events (MACEs). Safety endpoints were reported as non-coronary artery bypass grafting (CABG) related major bleeding and thrombolysis in myocardial infarction (TIMI) major bleeding. Risk ratio (RR) and 95% confidence interval (CI) were calculated for each outcome using a fixed effect model.

RESULTS

Five studies with a total of 3796 patients were included. In short-term follow up (30 days), bivalirudin significantly reduced non-CABG related major bleeding (p=0.0004) and TIMI major bleeding (p=0.007) compared to heparin plus GPIs. No significant differences were observed in rates of mortality, MI, repeat revascularization, stent thrombosis, and MACEs between the two groups in short- and long-term follow up (6 months to 3 years). In patients with ST elevated myocardial infarction (STEMI) with concurrent CKD, the decreased non-CABG related major bleeding (p=0.04) without increasing ischemic events was also observed after short-term follow up.

CONCLUSIONS

(1) Bivalirudin is safer than and as effective as heparin plus GPIs in CAD patients with CKD. (2) Impaired renal function does not affect the safety benefits of bivalirudin. (3) Similar efficacy profiles were identified between the two groups after both short- and long-term follow up in the CAD patients with CKD.

Efficacy and Safety of Bivalirudin Versus Heparins in Reduction of Cardiac Outcomes in Acute Coronary Syndrome and Percutaneous Coronary Interventions

Recent data suggest that bivalirudin, a reversible direct thrombin inhibitor, may be noninferior to heparins (unfractionated heparin/low molecular weight heparin) in providing protection against cardiovascular events, with significantly fewer bleeding complications. Whether this advantage is consistent has not been fully defined. We evaluated cardiac outcomes with bivalirudin vs the heparins in management of acute coronary syndromes (ACS), including patients undergoing percutaneous coronary interventions (PCI). Formal computer-aided searches of electronic databases (MEDLINE, PubMed, Cochrane Controlled Trials Registry) were performed by scrutiny of the reference lists of trials and review articles, abstracts, meeting proceedings, and the manufacturers of direct thrombin inhibitors. Five randomized controlled trials (BAT, 1995; CACHET, 2002; REPLACE-2, 2003; REPLACE-1, 2004; and ACUITY, 2006) comparing bivalirudin to the heparins in patients with ACS, including patients undergoing PCI, were identified. The meta-analysis consisted of 25 457 patients (bivalirudin, 15 077; heparins, 10 380). The primary safety end point was major bleeding, defined as intracranial, intraocular, or retroperitoneal hemorrhage; clinically overt blood loss leading to a hemoglobin drop exceeding 3 g/dL (or 10% of hematocrit) and transfusion of 2 or more units of whole blood or packed red blood cells. The combined relative risks (RR) across all of the studies and the 95% confidence intervals of death, myocardial infarction (MI), and revascularization (bivalirudin vs heparins) were computed using the Mantel-Haenszel fixed-effect model, whereas the random-effect model was used for major bleeding. A 2-sided α error < .05 was considered to be significant. There were no significant differences in patient characteristics between the 2 groups. Compared to the heparins, the risk of death, MI, revascularization, and composite ischemic end points were similar with bivalirudin monotherapy. However, the risk of major bleeding was significantly lower with bivalirudin use (RR = 0.553; 95% CI = 0.402-0.761; P = .001). The present meta-analysis suggests that bivalirudin may be noninferior to the heparins in reducing the composite of ischemic end points. Additionally, compared to the heparins, bivalirudin monotherapy may lower the rate of major bleeding.

The Use of Heparin during Endovascular Peripheral Arterial Interventions: A Synopsis

A large variety exists for many aspects of the use of heparin as periprocedural prophylactic antithrombotics (PPAT) during peripheral arterial interventions (PAI). This variation is present, not only within countries, but also between them. Due to a lack of (robust) data, no systematic review on the use of heparin during PAI could be justified. A synopsis of all available literature on heparin during PAI describes that heparin is used on technical equipment to reduce the thrombogenicity and in the flushing solution with saline. Heparin could have a cumulative anticoagulant effect when used in combination with ionic contrast medium. No level-1 evidence exists on the use of heparin. A measurement of actual anticoagulation status by means of an activated clotting time should be mandatory.

Bivalirudin Anticoagulant Therapy With or Without Platelet Glycoprotein IIb/IIIa Inhibitors During Transcatheter Coronary Interventional Procedures: A Meta-Analysis

The safety and effectiveness of using the direct thrombin inhibitor bivalirudin during transcatheter coronary interventional procedures remains uncertain.This study aimed to systematically assess anticoagulation with bivalirudin alone or bivalirudin plus glycoprotein (GP) IIb/IIIa inhibitors (bivalirudin-based anticoagulant therapy) in patients undergoing percutaneous coronary intervention (PCI) procedures by a meta-analysis of randomized controlled trials (RCTs).Systematical searches of the MEDLINE, EMBASE, and Cochrane databases were conducted. RCTs comparing bivalirudin-based anticoagulant therapy with a comparable heparin therapy in patients undergoing PCI were eligible. Risk ratios (RRs) with 95% confidence intervals (CIs) served as summary statistics.A total of 38,096 patients from 17 RCTs were randomized to the bivalirudin group (n = 18,878) or heparin group (n = 19,218) in the meta-analysis. No significant differences in death, myocardial infarction or reinfarction, ischemia-driven revascularization, or in-stent thrombosis were observed between the 2 groups (all P > 0.05). Notably, bivalirudin-based therapy showed a highly significant 34% decrease in the incidence of major bleeding (RR = 0.66; 95% CI 0.54-0.81; P < 0.001) and a 28% reduction in the need for blood transfusion (RR = 0.72; 95% CI 0.56-0.91; P < 0.01). Meta-regression analyses demonstrated that additional administration of GP IIb/IIIa receptor inhibitors (P = 0.01), especially eptifibatide (P = 0.001) and tirofiban (P = 0.002), was likely to increase the major bleeding risk associated with bivalirudin.Bivalirudin, in comparison to heparin, is associated with a markedly lower risk of major bleeding, and the additional use of GP IIb/IIIa inhibitors may weaken this benefit.

[Reversal for heparins and new anticoagulant treatments]

Even with unfractionated heparin or derivates, the reversal of pharmacologic anticoagulation is crucial in anticoagulated patients developing a life-threatening bleeding or scheduled for an emergency procedure. The antagonisation of unfractionated heparin is well codified: each milligram of protamine sulfate antagonizes 100 IU of heparin. Measurement of thrombin time reflects the anti-IIa effect of heparin and has to be monitored immediately and 1hour after the injection of protamine. The required dose of protamine sulfate depends on dosage and time of LMWH administration, although no clinical study supports these data. To date, there is no effective antidote for new anticoagulants (fondaparinux and other pentasaccharides, direct thrombin inhibitors, direct anti-Xa inhibitors). Some preliminary studies suggest the effectiveness of recombinant activated factor VII for pentasaccharides and activated or not Prothrombin Complex Concentrates and recombinant activated factor VII for oral anti-Xa and anti-IIa agents. Therefore, while the characteristics of these new anticoagulants could increase the comfort and improve the compliance, their development needs to ascertain the lack of increase in bleeding complications and the need for a safe and effective antidote.

Comparison of safety and efficacy of bivalirudin versus unfractionated heparin in high-risk patients undergoing percutaneous coronary intervention (from the Anti-Thrombotic Strategy for Reduction of Myocardial Damage During Angioplasty-Bivalirudin vs Heparin study)

Bivalirudin, a direct thrombin inhibitor, is as effective as unfractionated heparin (UFH), with decreased bleeding in patients with acute coronary syndromes who undergo percutaneous coronary intervention (PCI). The aim of this study was to evaluate the effectiveness of bivalirudin versus UFH in selected PCI patients at high bleeding risk. Four hundred one consecutive patients who underwent PCI fulfilling ≥ 1 enrollment criterion (age >75 years, chronic renal failure, and diabetes mellitus) were randomized to bivalirudin (bolus 0.75 mg/kg followed by infusion during the procedure; n = 198) or UFH (75 IU/kg; n = 203). In the overall population, 39% were aged >75 years, 22% had renal failure, 63% had diabetes, and 29% had acute coronary syndromes. The primary efficacy end point was the 30-day incidence of major adverse cardiac events (cardiac death, myocardial infarction, stent thrombosis, or target vessel revascularization). The primary safety end point was the occurrence of any bleeding or entry-site complications after PCI. All patients were preloaded with clopidogrel 600 mg. Glycoprotein IIb/IIIa inhibitors were used at the operators' discretion. Thirty-day major adverse cardiac event rates were 11.1% in the bivalirudin group and 8.9% in the UFH group (p = 0.56); the primary efficacy end point was reached mainly because of periprocedural myocardial infarction; 1 patient in the bivalirudin group had stent thrombosis. Occurrence of the primary safety end point was 1.5% in the bivalirudin group and 9.9% in the UFH group (p = 0.0001); this benefit was essentially driven by the prevention of entry-site hematomas >10 cm (0.5% vs 6.9%, p = 0.002). In conclusion, Anti-Thrombotic Strategy for Reduction of Myocardial Damage During Angioplasty-Bivalirudin vs Heparin (ARMYDA-7 BIVALVE) indicates that bivalirudin, compared with UFH, causes significantly lower bleeding and has a similar incidence of major adverse cardiac events in patients with older age, diabetes mellitus, or chronic renal failure who undergo PCI.

Meta-analysis comparing bivalirudin versus heparin monotherapy on ischemic and bleeding outcomes after percutaneous coronary intervention

With femoral access, bivalirudin decreases risks of major bleeding after percutaneous coronary intervention (PCI) and provides better net clinical benefit compared to unfractionated heparin (UFH) plus planned glycoprotein IIb/IIIa inhibitors. Whether this benefit exists compared to UFH monotherapy is less clear. We performed a systematic review and meta-analysis to compare outcomes in patients undergoing transfemoral PCI with UFH or bivalirudin. Randomized trials (n = 3) and observational studies (n = 13) comparing bivalirudin to UFH monotherapy were reviewed. Primary outcomes were 30-day rates of major adverse cardiovascular events (MACEs) including death, myocardial infarction (MI), urgent revascularization, as well as all-cause mortality, MI, major bleeding, and blood transfusion. We collected data from 16 studies involving 32,492 patients undergoing PCI. Most observational studies were performed in the United States, whereas all randomized trials were done in Europe. Compared to UFH monotherapy, bivalirudin was associated with similar risk of MACEs (odds ratios [OR] 0.92, 95% confidence interval [CI] 0.75 to 1.12), a substantial 45% relative decrease in major bleeding (OR 0.55, 95% CI 0.43 to 0.72), and a trend in the decrease of transfusion (OR 0.87, 95% CI 0.70 to 1.08). A decrease in mortality was seen in observational studies (OR 0.62, 95% CI 0.45 to 0.85) but remained inconclusive in randomized trials (OR 0.63, 95% CI 0.20 to 2.01). MI rate was similar with the 2 anticoagulants. In conclusion, in patients undergoing transfemoral PCI, the benefit of bivalirudin over UFH monotherapy is driven by a significant decrease in major bleeding with similar rates of MACE. As PCI practice moves toward other bleeding-avoidance strategies such as the radial approach, future studies should focus on the interaction between anticoagulant strategy and access-site choice.

Direct thrombin inhibitors in cardiovascular disease

Limitations of commonly used anticoagulants, unfractionated heparin, low-molecular-weight heparin, and oral vitamin K antagonists have prompted the development of alternative therapies. Direct thrombin inhibitors are a new class of anticoagulants that bind directly to thrombin and inhibit its interaction with substrates. In this Review, we critically examine the evidence from randomized controlled trials for the efficacy and safety of the parenteral direct thrombin inhibitors bivalirudin and argatroban, and the novel oral direct thrombin inhibitor dabigatran etexilate, in cardiovascular and thrombotic disease.

Bivalirudin inhibits periprocedural platelet function and tissue factor expression of human smooth muscle cells

AIM

A major concern of stent implantation after percutaneous coronary intervention (PCI) is acute stent thrombosis. Effective inhibition of periprocedural platelet function in patients with coronary artery disease (CAD) leads to an improved outcome. In this study, we examined the periprocedural platelet reactivity after administrating bivalirudin during PCI compared to unfractionated heparin (UFH) administration. Further, the effect of bivalirudin on induced tissue factor (TF) expression in smooth muscle cells (SMC) was determined.

METHODS

Patients with CAD (n = 58) and double antithrombotic medication were treated intraprocedural with UFH (n = 30) or bivalirudin (n = 28). Platelet activation markers were flow cytometrically measured before and after stenting. The expression of TF in SMC was determined by real-time PCR and Western blotting. The thrombogenicity of platelet-derived microparticles and SMC was assessed via a TF activity assay.

RESULTS

Bivalirudin significantly diminished the agonist-induced platelet reactivity post-PCI. Compared to UFH treatment, the adenosine diphosphate (ADP) and thrombin receptor-activating peptide (TRAP)-induced thrombospondin expression post-PCI was reduced when bivalirudin was administrated during intervention. In contrast to UFH, bivalirudin reduced the P-selectin expression of unstimulated and ADP-induced platelets post-PCI. Moreover, bivalirudin inhibited the thrombin-, but not FVIIa- or FVIIa/FX-induced TF expression and pro-coagulant TF activity of SMC. Moreover, bivalirudin reduced the TF activity of platelet-derived microparticles postinduction with TRAP or ADP.

CONCLUSIONS

Bivalirudin is better than UFH in reducing periprocedural platelet activation. Moreover, thrombin-induced TF expression is inhibited by bivalirudin. Thus, bivalirudin seems to be a better anticoagulant during PCI than UFH.

Pharmacological prevention of peri-, and post-procedural myocardial injury in percutaneous coronary intervention

In recent years, percutaneous coronary intervention (PCI) has become a well-established technique for the treatment of coronary artery disease. PCI improves symptoms in patients with coronary artery disease and it has been increasing safety of procedures. However, peri- and post-procedural myocardial injury, including angiographical slow coronary flow, microvascular embolization, and elevated levels of cardiac enzyme, such as creatine kinase and troponin-T and -I, has also been reported even in elective cases. Furthermore, myocardial reperfusion injury at the beginning of myocardial reperfusion, which causes tissue damage and cardiac dysfunction, may occur in cases of acute coronary syndrome. Because patients with myocardial injury is related to larger myocardial infarction and have a worse long-term prognosis than those without myocardial injury, it is important to prevent myocardial injury during and/or after PCI in patients with coronary artery disease. To date, many studies have demonstrated that adjunctive pharmacological treatment suppresses myocardial injury and increases coronary blood flow during PCI procedures. In this review, we highlight the usefulness of pharmacological treatment in combination with PCI in attenuating myocardial injury in patients with coronary artery disease.

Comparison of bivalirudin versus heparin plus glycoprotein IIb/IIIa inhibitors in patients undergoing an invasive strategy: a meta-analysis of randomized clinical trials

OBJECTIVE

This meta-analysis was performed to assess the efficacy and safety of bivalirudin compared with unfractionated heparin or enoxaparin plus glycoprotein (GP) IIb/IIIa inhibitors in patients undergoing percutaneous coronary intervention (PCI).

BACKGROUND

Pharmacotherapy for patients undergoing PCI includes bivalirudin, heparin, and GP IIb/IIIa inhibitors. We sought to compare ischemic and bleeding outcomes with bivalirudin versus heparin plus GP IIb/IIIa inhibitors in patients undergoing PCI.

METHODS

A literature search was conducted to identify fully published randomized trials that compared bivalirudin with heparin plus GP IIb/IIIa inhibitors in patients undergoing PCI.

RESULTS

A total of 19,772 patients in 5 clinical trials were included in the analysis (9785 patients received bivalirudin and 9987 patients received heparin plus GP IIb/IIIa inhibitors during PCI). Anticoagulation with bivalirudin, as compared with heparin plus glycoprotein IIb/IIIa inhibitors, results in no difference in major adverse cardiovascular events (odds ratio [OR] 1.07, 95% confidence interval [CI] 0.96 to 1.19), death (OR 0.93, 95% CI 0.72 to 1.21), or urgent revascularization (OR 1.06, 95% CI 0.86 to 1.30). There is a trend towards a higher risk of myocardial infarction (OR 1.12, 95% CI 0.99 to 1.28) but a significantly lower risk of TIMI major bleeding with bivalirudin (OR 0.55, 95% CI 0.44 to 0.69).

CONCLUSION

In patients who undergo PCI, anticoagulation with bivalirudin as compared with unfractionated heparin or enoxaparin plus GP IIb/IIIa inhibitors results in similar ischemic adverse events but a reduction in major bleeding.

Practical strategies for the management of anticoagulation therapy: unsolved issues in the cardiac catheterization laboratory

PURPOSE

Percutaneous coronary intervention (PCI) is the preferred reperfusion strategy in the management of patients with ST-elevation myocardial infarction (STEMI) and higher-risk patients with unstable angina/non-STEMI (UA/NSTEMI). Recent updates have been issued for guidelines from the American College of Cardiology and American Heart Association delineating the appropriate use of anticoagulants as ancillary therapies to PCI. This manuscript reviews the recent clinical trial data supporting the updated guidelines and highlights remaining areas of uncertainty.

METHODS

SCOPUS and Pubmed were searched for relevant English-language reports of clinical trials, registries, articles and case reports. Search terms included but were not limited to: PCI, anticoagulation, ancillary, STEMI, NSTEMI, angina, acute coronary syndrome. The reference lists of identified articles were searched for additional relevant publications.

RESULTS

Unfractionated heparin (UFH), the historical standard of care for anticoagulation in STEMI and NSTEMI patients undergoing PCI, is sub-optimal and the list of anticoagulants recommended for alternatives in the current guidelines has expanded to include superior anticoagulants, including the low-molecular-weight heparin enoxaparin and the direct thrombin inhibitor bivalirudin. Additionally, fondaparinux is recommended if supplemented during PCI by an additional agent with anti-IIa activity. However, uncertainties in the guidelines remain. Clinical discretion is still required when deciding which anticoagulant to use, ensuring seamless transitions throughout the care pathway, and how to correctly identify the risk status of a patient and modify anticoagulant regimens accordingly, such as in special patient populations.

CONCLUSIONS

The published evidence supports the updates to the guidelines. Updated guidelines still have knowledge gaps which require the application of clinical discretion by the cardiologist.

Bleeding risk and the management of bleeding complications in patients undergoing anticoagulant therapy: focus on new anticoagulant agents

For more than 60 years, heparin and coumarin have been mainstays of anticoagulation therapy. They are widely available, inexpensive, effective, and have specific antidotes but are regarded as problematic because of their need for careful monitoring. In addition, coumarin has a delayed onset of action, interacts with many medications, has a narrow therapeutic window, and is paradoxically prothrombotic in certain settings (ie, can precipitate “coumarin necrosis”). Heparin may require monitoring of its therapeutic effect and can also cause thrombosis (heparin-induced thrombocytopenia/thrombosis syndrome). These limitations have led to the development of new anticoagulants with the potential to replace current agents. These newer agents fall into 2 classes, based on whether they are antithrombin dependent (low-molecular-weight heparin, fondaparinux) or antithrombin independent (direct inhibitors of factor Xa and thrombin [factor IIa]). This paper addresses newer anticoagulants, reviewing their efficacy and limitations, and focuses on the risk of major bleeding that may complicate their use. In contrast to heparin and coumarin, none of these newer agents has a specific antidote that completely reverses its anticoagulant effect. Available data on the efficacy and safety of current and experimental agents for anticoagulant reversal are reviewed, and a plan for management of anticoagulant-induced bleeding is presented.

Impact of bivalirudin on outcomes after percutaneous coronary revascularization with drug-eluting stents

BACKGROUND

The direct thrombin inhibitor bivalirudin has been found to be noninferior to heparin plus planned glycoprotein (GP) IIb/IIIa blockade in the prevention of acute ischemic end points and 1-year mortality after percutaneous coronary intervention (PCI) with bare metal stents. We investigated whether long-term outcomes after bivalirudin use remained comparable to heparin plus GP IIb/IIIa blockade in current clinical practice of drug-eluting stent use.

METHODS

Using the 2004-2005 Cornell Angioplasty Registry, we studied 2504 consecutive patients undergoing urgent or elective PCI with periprocedural use of bivalirudin or heparin plus GP IIb/IIIa platelet inhibitors. Patients presenting with an acute ST-elevation myocardial infarction (MI) < or = 24 hours, thrombolytic therapy < or = 7 days, hemodynamic instability/shock, or renal insufficiency were excluded.

RESULTS

Of the study cohort, 1340 patients (54%) received bivalirudin and 1164 patients (46%) received heparin plus GP IIb/IIIa blockade. The incidence of inhospital mortality (0.3% vs 0.2%, P = .692), MI (6.6% vs 8.1%, P = .191), and combined end point of death, stroke, emergent coronary artery bypass graft/PCI, and MI (6.9% vs 8.3%, P = .199) was similar in the bivalirudin and heparin plus GP IIb/IIIa inhibitor groups. There was a lower incidence of major (0.7% vs 1.9%, P = .012) and minor bleeding (9.6% vs 15.6%, P < .001) in the bivalirudin versus heparin plus GP IIb/IIIa inhibitor group. Mean clinical follow-up was 24.8 +/- 7.7 months. At follow-up, there were 87 (6.5%) deaths in the bivalirudin group versus 42 (3.6%) in the heparin plus GP IIb/IIIa inhibitor group (hazard ratio 1.87, 95% CI 1.30-2.71, P = .001). After a propensity score adjusted multivariate Cox analysis, bivalirudin use was associated with a nonsignificant trend toward increased long-term mortality (hazard ratio 1.45, 95% CI 0.98-2.16, P = .065).

CONCLUSIONS

Compared with heparin plus GP IIb/IIIa inhibition, routine use of bivalirudin as the procedural anticoagulant in contemporary PCI with drug-eluting stents was associated with lower rates of inhospital complications and similar long-term all-cause mortality.

Similar Success Rates with Bivalirudin and Unfractionated Heparin in Bare-Metal Stent Implantation

BACKGROUND

Unfractionated heparin (UFH) is the traditional agent utilized during percutaneous peripheral interventions (PPIs) despite its well-known limitations. Bivalirudin, a thrombin-specific anticoagulant, overcomes many of the limitations of UFH and has consistently demonstrated comparable efficacy with significantly fewer bleeding complications. The purpose of this study was to compare procedural success in patients undergoing bare-metal stent implantation for atherosclerotic blockage of the renal, iliac, and femoral arteries and receiving either bivalirudin (0.75 mg/kg bolus/1.75 mg/kg/hr infusion) or UFH (50-70 U/kg/hr bolus) as the primary anticoagulant.

METHODS

This study was an open-label, nonrandomized retrospective registry with the primary endpoint of procedural success. Secondary endpoints included incidence of: death, myocardial infarction (MI), urgent revascularization, amputation, and major and minor bleeding.

RESULTS

One hundred and five consecutive patients were enrolled (bivalirudin = 53; heparin = 52). Baseline demographics were comparable between groups. Patients were pretreated with clopidogrel (approx. 71%) and aspirin (approx. 79%). Procedural success was achieved in 97% and 96% of patients in the bivalirudin- and heparin-treated groups, respectively. Event rates were low and similar between groups.

CONCLUSION

Bivalirudin maintained an equal rate of procedural success in this cohort without sacrificing patient safety. Results of this study add to the growing body of evidence supporting the safety and efficacy of bivalirudin as a possible substitute for UFH in anticoagulation during peripheral vascular bare-metal stent implantation.

Comparison of access-related bleeding complications in women versus men undergoing percutaneous coronary catheterization using the radial versus femoral artery

Women constitute a high-risk population for bleeding, which is a major prognostic predictor after percutaneous coronary catheterization procedures. We prospectively followed 3,261 consecutive percutaneous coronary procedures performed by radial artery catheterization (RAC) or femoral artery catheterization (FAC). The primary study objective was to determine the relative incidences of in-hospital major and minor puncture-related hemorrhages. Secondary objectives were to (1) identify predictors of major bleeds and (2) estimate how often a second, alternative access site is required for catheterization. In women, no major bleeding occurred after 299 RAC procedures performed, whereas 25 major bleeding episodes occurred after 601 FAC procedures (p = 0.0008). Women who underwent RAC also had a significantly lower incidence of minor hemorrhages than women who underwent FAC (19 of 299, 6.4%, vs 237 of 601, 39.4%, respectively, p = 0.00001). On multivariate analysis, independent predictors of major bleeding were FAC (odds ratio [OR] 27.4, 95% confidence interval [CI] 3.8 to 199.9), use of glycoprotein IIb/IIIa inhibitors (OR 5.6, 95% CI 2.7 to 11.9), female gender (OR 4.5, 95% CI 2.2 to 9.0), age >70 years (OR 2.4, 95% CI 1.2 to 4.8), and an acute coronary syndrome setting (OR 2.4, 95% CI 1.1 to 5.0). Women who underwent RAC were more likely to require a second access site than men (14% vs 1.7%), but operators less selective in RAC use successfully completed the procedure by radial approach in >90% of patients. In conclusion, extensive RAC was more effective at preventing access-related bleeding complications in women than FAC.

Bivalirudin in percutaneous coronary intervention

Bivalirudin is a member of the direct thrombin inhibitor group of anticoagulants. It has been evaluated as an alternative to unfractionated and low-molecular-weight heparins in the settings of percutaneous coronary intervention (PCI) and acute coronary syndrome (ACS). Results of clinical trials to date suggest bivalirudin is a viable alternative to the use of a heparin combined with a glycoprotein (GP) IIb/IIIa inhibitor in these settings. Thrombin has a central role in coagulation and platelet activation in ACS and during PCI. Its direct inhibition is an attractive target for therapy in these settings. Bivalirudin is a 20 amino acid polypeptide hirudin analog. It displays bivalent and reversible binding to the thrombin molecule, inhibiting its action. Direct inhibition of thrombin with bivalirudin has theoretical pharmacokinetic and pharmacodynamic advantages over the indirect anticoagulants. A reduction in rates of bleeding without loss of anti-thrombotic efficacy has been a consistent finding across multiple clinical trials. There may be economic benefits to the use of bivalirudin if it permits a lower rate of use of the GP IIb/IIIa inhibitors. This article reviews the pharmacology of bivalirudin and clinical trial evidence to date. There are now data from multiple clinical trials and meta-analyses in the setting of ACS and PCI. Early results from the acute catheterization and urgent intervention strategy (ACUITY) trial are discussed.

Direct antithrombins: mechanisms, trials, and role in contemporary interventional medicine

Direct thrombin inhibitors have several potential advantages over indirect thrombin inhibitors such as heparin. Bivalirudin, a bivalent direct thrombin inhibitor, is most commonly used in clinical practice and has a proven role in contemporary interventional medicine with elective percutaneous coronary intervention (PCI) as well as in patients with non-ST-elevation acute coronary syndrome (NSTEACS). Results from well-controlled clinical trials have shown that bivalirudin is associated with an approximate 50% reduction in major bleeding while having similar effects on incidence of death and myocardial infarction (MI) compared with herapin or enoxaparin and glycoprotein IIb/IIIa inhibitors. Bivalirudin has been successfully used in off- and on-pump cardiac surgery. Argatroban is the most evaluated among the univalent direct thrombin inhibitors inhibiting only the catalytic site of thrombin. It has been associated with similar rates of major bleeding compared with heparin in patients with acute MI receiving either streptokinase or alteplase with no effects on clinical endpoints. In a meta-analysis of 11 randomised trials where direct thrombin inhibitors (hirudin, bivalirudin, argatroban, efegatan or inogatran) were compared with unfractionated heparin in >35,000 patients with ST-elevation MI (STEMI) or NSTEACS there was no mortality difference between treatment groups but the incidence of MI at 30 days was significantly reduced in patients treated with direct thrombin inhibitors compared with heparin (4.7% vs 5.3%; p < 0.004). The role of direct thrombin inhibitors in both primary angioplasty for STEMI and angioplasty after fibrinolytic therapy needs to be established. Overall, the efficacy and improved safety profile make bivalirudin an attractive first-line anticoagulant for elective PCI and in patients with NSTEACS undergoing an invasive strategy.

Direct Vascular Effects of Protease-Activated Receptor Type 1 Agonism In Vivo in Humans

Background— Protease-activated receptor type 1 (PAR-1) has been proposed as the principal thrombin receptor in humans, although its actions in vivo have not been defined. The aim of the present study was to determine the direct vascular actions of PAR-1 agonism in humans.

Methods and Results— Dorsal hand vein diameter was measured by the Aellig technique in 14 healthy volunteers during local intravenous SFLLRN (PAR-1 agonist; 0.05 to 15 nmol/min) and SLIGKV (PAR-2 agonist; 1.6 to 160 nmol/min) infusions. The venous effects of SFLLRN were further assessed in the presence or absence of norepinephrine or the glycoprotein IIb/IIIa antagonist tirofiban. Forearm blood flow was measured by venous occlusion plethysmography in 16 volunteers during infusion of SFLLRN (1 to 50 nmol/min), SLIGKV (160 to 800 nmol/min), and the endothelium-dependent vasodilator bradykinin (100 to 1000 pmol/min). Platelet-monocyte binding (a sensitive measure of platelet activation) and plasma tissue plasminogen activator (tPA), plasminogen-activator inhibitor 1, and von Willebrand factor concentrations were measured at intervals throughout the study. SFLLRN caused dose-dependent venoconstriction ( P <0.001) that was unaffected by norepinephrine or tirofiban co-infusion. In forearm resistance vessels, SFLLRN increased forearm blood flow ( P <0.001), tPA release ( P <0.001), and platelet-monocyte binding ( P <0.0001) without affecting plasma plasminogen-activator inhibitor 1 or von Willebrand factor concentrations. SLIGKV caused venous ( P <0.001) and arterial ( P <0.01) dilatation without tPA release.

Conclusions— We have demonstrated that PAR-1 agonism causes platelet activation, venous constriction, arterial dilatation, and tPA release in vivo in humans. These unique and contrasting effects provide important insights into the physiological and pathophysiological role of thrombin in the human venous and arterial circulations.

Cardiac events after low osmolar ionic or isosmolar nonionic contrast media utilization in the current era of coronary angioplasty

OBJECTIVES

Our study aimed to compare the isosmolar nonionic dimer iodixanol and the low osmolar ionic agent ioxaglate in the current era of percutaneous coronary intervention (PCI), using clopidogrel, enoxaparine, direct stenting, and drug eluting stent.

BACKGROUND

Previous studies have suggested an association between thrombus-related events and type of contrast media.

METHODS

Our prospective single-center study included 498 consecutive patients who were assigned to receive either iodixanol (n = 231) or ioxaglate (n = 267). The primary endpoint was the cumulative rate of in-hospital major adverse clinical events (MACE). A secondary endpoint was the rate of angiographic or procedural complications.

RESULTS

Clinical and angiographic baseline characteristics and procedural data were similar in the 2 groups. A peak anti-Xa > 0.5 IU/ml was obtained in 97% in both groups. Glycoprotein IIb/IIIa inhibitors were used in 42% of patients. Coronary stenting was performed in 91% of patients, with direct stenting in 70%, and drug-eluting stent in 28% of patients. In-hospital MACE was more frequent in patients receiving iodixanol compared with those receiving ioxaglate (4.8% vs. 0.3%, P < 0.005). This difference was mainly related to the appearance of a large thrombus during PCI (6% with iodixanol vs. 0.3% with ioxaglate, P < 0.0001). In multivariate analysis, independent predictors of in-hospital MACE were use of iodixanol (P < 0.01), the higher number of stent used (P < 0.008), bifurcation/ostial lesion (P < 0.01), and balloon dilation before stenting (p < 0.001).

CONCLUSIONS

In our study reflecting the current era of PCI, thrombus-related events are more frequent with the isosmolar nonionic dimer iodixanol than with the low osmolar ionic agent ioxaglate.