The CIAO (Coronary Interventions Antiplatelet-based Only) Study

Translating proof-of-concept for platelet slip into improved antithrombotic therapeutic regimens

Platelets are central to thrombosis. Research at the intersection of biological and physical sciences provides proof-of-concept for shear rate-dependent platelet slip at vascular stenosis and near device surfaces. Platelet slip extends the observed biological "slip-bonds" to the boundary of functional gliding without contact. As a result, there is diminished engagement of the coagulation cascade by platelets at these surfaces. Comprehending platelet slip would more precisely direct antithrombotic regimens for different shear environments, including for percutaneous coronary intervention (PCI). In this brief report we promote translation of the proof-of-concept for platelet slip into improved antithrombotic regimens by: (1) reviewing new supporting basic biological science and clinical research for platelet slip; (2) hypothesizing the principal variables that affect platelet slip; (3) applying the consequent construct model in support of-and in some cases to challenge-relevant contemporary guidelines and their foundations (including for urgent, higher-risk PCI); and (4) suggesting future research pathways (both basic and clinical). Should future research demonstrate, explain and control platelet slip, then a paradigm shift for choosing and recommending antithrombotic regimens based on predicted shear rate should follow. Improved clinical outcomes with decreased complications accompanying this paradigm shift for higher-risk PCI would also result in substantive cost savings.

Hemorrhagic stroke during the acute phase of myocardial infarction: a rare and difficult situation to manage

Given the ischemic risk due to the hypercoagulability associated with acute coronary syndromes, the administration of antiplatelet and antithrombotic agents is necessary to prevent intracoronary and postprocedural thrombosis during percutaneous coronary interventions. However, the risk of bleeding, hemorrhagic stroke included, is real, although it has a lower prevalence, and it complicates the management of the coronary event if it happens. We report the case of a 66 years old patient with no prior pathological history who was initially admitted for acute coronary syndromes, complicated by paroxysmal atrial fibrillation that was successfully thrombolysed. Subsequently, the patient benefited from a drug-eluting stent angioplasty of the proximal circumflex artery, performed within 24 hours after the symptomatology onset. Following angioplasty, the patient presented with a left parietal intraparenchymal hematoma not indicating surgery. The double antiplatelet therapy was consequently withdrawn. Two days later, the patient presented with an ST-segment elevation infarction recurrence, inciting the resumption of the dual antiplatelet aggregation therapy. On evolution, the neurological state was still stable with a stationary aspect of the hematoma on cerebral imagery but without angina recurrence or electrocardiographic modifications. Hemorrhagic complications' occurrence following thrombolysis or angioplasty for ST-segment elevation infarction challenges the short and long-term management of the disease and must push practitioners to better weigh the risks and benefits before any medication administration decision.

The Evolution of Anticoagulation for Percutaneous Coronary Intervention: A 40-Year Journey

The selection of antithrombotic strategies continue to be of utmost importance during percutaneous coronary intervention (PCI) and have evolved over the past 40 years. Although the backbone of therapy during PCI continues to be a combination of oral antiplatelets and parenteral anticoagulants, a variety of different approaches have been tested over time. In particular, different choices of anticoagulation management have been tested in the stable ischemic heart disease and acute coronary syndrome setting. Evaluation of alternative regimens in the quest to balance ischemic and bleeding risk have undoubtedly improved patient care with PCI. In the current review we highlight the evolution of evidence-based therapeutic options over the past 40 years from the beginning of coronary angioplasty to contemporary PCI. We provide insight into future therapeutic options and provide a contemporary overview of anticoagulation choices for patients who require PCI on the basis of up-to-date evidence balancing ischemic and bleeding risk and according to clinical presentation.

Three-year outcome of directional atherectomy and drug coated balloon for the treatment of common femoral artery steno-occlusive lesions

BACKGROUND

Endarterectomy is considered the gold standard therapy for common femoral artery (CFA) steno-occlusive lesions, but a significant risk of perioperative mortality and complications has been reported.

OBJECTIVE

Aim of this study is to evaluate the efficacy at a long-term follow-up of patients with CFA steno-occlusive lesions treated with directional atherectomy and drug coated balloon (DCB).

MATERIAL AND METHODS

In this single-center registry, 78 patients (male: 80.7%; age: 71 ± 15 years; occlusions: 25%) with 80 CFA lesions were included, with 39.7% of them undergoing directional atherectomy and drug coated balloon due to critical limb ischemia and 60.3% due to lower-limb intermittent claudication. The long-term follow-up was completed by 75 patients (3 years). The 31 patients with critical ischemia (39.7%) were further subdivided into 20 (25.6%) patients with pain at rest and 11 (14.1%) with trophic changes, ulcers and/or tissue loss. We considered the primary and the secondary outcome, referring, respectively to peak systolic velocity ratio (PSVR) ≥ 2.4 on duplex or > 50% stenosis on digital subtraction angiography at 36 months and to clinically driven target lesion revascularization at 36 months.

RESULTS

The primary and secondary outcome was obtained in 84% and 86.7% of patients, at 36 months of follow up. Bailout stenting was necessary in 6/80 cases (7.5%) for suboptimal result. Freedom from MALE was obtained in 98.6% of patients.

CONCLUSIONS

These results confirm that directional atherectomy and drug coated balloon strategy for the treatment of CFA lesions is effective at a long-term follow-up and could be considered as a good alternative to surgery.

Routine fixed-dose heparin vs. ACT-guided heparin administration for elective PCI and its influence on patient in-hospital outcome: a retrospective study

OBJECTIVE

Activated clotting time (ACT)-based heparin dosing during percutaneous intervention (PCI) is recommended by Society guidelines. However, the relationship between ACT and outcome in the setting of elective PCI has not been sufficiently studied. We sought to evaluate the in-hospital outcome of patients undergoing elective PCI while receiving fixed-dose heparin without ACT measurement versus those with ACT-guided management.

METHODS

This retrospective study included consecutive patients undergoing elective PCI in a single-center between 11/2015 and 12/2018. Patients were divided into two groups, depending on whether ACT was measured. Heparin-only anticoagulation and non-femoral procedures were allowed. Patient demographics, procedural data and in-hospital outcomes were collected. The primary outcome was in-hospital major adverse cardiovascular events (MACE), secondary (safety) outcomes were in-hospital definite stent thrombosis, Bleeding Academic Research Consortium bleeding, access-related complications (any) as well as peri-procedural complications.

RESULTS

In total, 500 procedures were included in the study, 151 ACT and 349 fixed-dose. Patient demographics and medical history in both groups were well balanced, but those having ACTs were younger (63.2 ± 10.9 vs. 66.5 ± 11.3; P = 0.003) and less likely to have a history of coronary artery disease (74 vs. 82%; P = 0.032) or kidney failure. Procedural data were similar; however, total heparin dose and procedure length were higher in the ACT group (6232 ± 1388 vs.5032 ± 417 units; P < 0.001; 40.1 ± 14.0 vs. 30.3 ± 12.7 min; P < 0.001). Primary and secondary outcome events were rare and similar (MACE 1.1 vs. 1.3%; P = 0.86).

CONCLUSIONS

A fixed-dose heparin injection (5000 IU) approach for elective PCI while omitting ACT offers slightly shortened procedural time and similar in-hospital safety profile.

Contemporary use of anticoagulation in the cardiac catheterization laboratory: a review

Anticoagulation during percutaneous coronary interventions has a rich history that has been shaped by several key clinical trials. The correct choice of anticoagulation during interventions can maximize patient outcomes and ensure a safe procedure. However, in some specific situations, anticoagulation may not be required at all. In this review article, we review the significant clinical trials and current guidelines regarding the use of anticoagulation in the catheterization laboratory and discuss the unique pharmacological aspects of the most commonly used agents, with an emphasis on the specific pharmacokinetic parameters that dictate how these agents are used and monitored. Finally, we discussed the future directions in anticoagulation therapy in coronary artery disease. This review serves as a robust synopsis of the clinical data for practicing clinicians and fellows in training.

Successful Percutaneous Balloon Angioplasty in a Patient Presenting With STEMI and Acute Intracranial Hemorrhage

Percutaneous coronary interventions (PCI) mandates the administration of anti-platelet and anti-thrombotic agents to prevent intracoronary and post-procedural thrombosis upon introducing thrombogenic foreign bodies such as intracoronary wires, balloons, or stents, especially in the setting of acute coronary syndrome (ACS) given the hypercoagulable state associated with it. This is a case of a 54-year-old female who presented to the emergency department with left-sided weakness and dysarthria for an unknown duration. A CT scan of the head showed acute right middle cerebral artery distribution infarct. She subsequently underwent a successful thrombectomy. Four hours later, the patient became lethargic and nauseous. Electrocardiogram showed anterior wall ST elevation with new-onset anterior wall akinesia on transthoracic echocardiogram. Repeat CT of the head showed acute intracranial hemorrhagic conversion. She then developed cardiac arrest mandating emergent cardiac catheterization. Coronary angiogram revealed 100% occlusion in a mid left anterior descending artery (LAD) and 80% in a left circumflex artery (LCX) and chronic total occlusion of the right coronary artery (RCA). After weighing risks and benefits, PCI was performed with rapid plain old balloon angioplasty (POBA) to the 100% thrombotic lesion in the LAD with successful restoration of flow without administering anti-platelet or anti-thrombotic agents given the acute intracranial hemorrhage, She was then discharged to a rehab facility a few days later in stable condition. This case demonstrates successful percutaneous coronary intervention in the 100% occluded LAD in a life-threatening situation despite not using anticoagulation or antiplatelet therapy due to active intracranial hemorrhage.

Percutaneous Coronary Intervention With an Initial Bolus of Low-Dose Heparin in Biomarker-Negative Patients

OBJECTIVES

The safety and efficacy of an initial intravenous bolus of low-dose heparin (40 IU/kg) was evaluated in biomarker negative patients undergoing percutaneous coronary intervention (PCI).

BACKGROUND

A bolus of 70-100 IU/kg of heparin is currently recommended for patients undergoing PCI. However, the ideal dose of heparin has not been evaluated in a randomized trial. The higher dose of 100 IU/kg may increase the risk of bleeding. An initial bolus of low-dose heparin may be advantageous to avoid supratherapeutic activating clotting times (ACT) while still allowing for the administration of additional heparin if the ACT is subtherapeutic.

METHODS

From January 2008 to February 2020, 904 patients undergoing elective transfemoral PCI received an initial bolus of 40 IU/kg of heparin. Patients who underwent transradial PCI were not included. Patients were routinely pretreated with dual antiplatelet therapy. The primary end point was the composite of cardiac death, myocardial infarction (MI), urgent target vessel revascularization (TVR) for ischemia, or major bleeding within 30 days after PCI.

RESULTS

The initial mean activating clotting time was 235.4 ± 26.6 s. The clinical event rates were low: the primary end point occurred in 5.3%, cardiac death in 1.0%, MI in 3.1%, urgent TVR in 0.7% and major bleeding in 1.9%. Stent thrombosis was uncommon (0.2%). No patients developed profound thrombocytopenia. Three patients (0.3%) had acute limb ischemia that required revascularization.

CONCLUSION

An initial strategy of low-dose heparin is associated with low ischemic and bleeding complications in biomarker negative patients who undergo transfemoral PCI.

Validated model of platelet slip at stenosis and device surfaces

Platelets are central to thrombosis. However, it is unknown whether platelets slip at vascular or device surfaces. The presence of platelet slip at a surface would interrupt physical contact between the platelet and that surface, and therefore diminish adhesion and thrombosis. Unfortunately, no existing technology can directly measure platelet slip in a biological environment. The objective of this study was to explore whether microspheres-modeling platelets-slip at different vascular and device surfaces in an acrylic scaled-up model coronary artery. The microspheres (3.12 µm diameter) were suspended in a transparent glycerol/water experimental fluid, which flowed continuously at Reynolds numbers typical of coronary flow (200-400) through the model artery. We placed a series of axisymmetric acrylic stenoses (cross-sectional area reduction [CSAr], 20-90%) into the model artery, both without and with a central cylinder present (modeling a percutaneous interventional guide wire, and with a scaled-up Doppler catheter mounted upstream). We used laser Doppler velocimetry (LDV) to measure microsphere velocities within, proximal and distal to each stenosis, and compared to computer simulations of fluid flow with no-slip. For validation, we replaced the acrylic with paraffin stenoses (more biologically relevant from a surface roughness perspective) and then analyzed the signal recorded by the scaled-up Doppler catheter. Using the LDV, we identified progressive microsphere slip proportional to CSAr inside entrances for stenoses ≥60% and ≥40% without and with cylinder present, respectively. Additionally, microsphere slip occurred universally along the cylinder surface. Computer simulations indicated increased fluid shear rates (velocity gradients) at these particular locations, and logistic regression analysis comparing microsphere slip with fluid shear rate resulted in a c-index of 0.989 at a cut-point fluid shear rate of (10.61 [cm^-1]×mean velocity [cm×sec^-1]). Moreover, the presence of the cylinder caused disordering of microsphere shear rates distal to higher grade stenoses, indicating a disturbance in their flow. Finally, despite lower precision, the signal recorded by the scaled-up Doppler catheter nonetheless indicated slip at the entry into and at most locations distal to the 90% stenosis. Our validated model establishes proof of concept for platelet slip, and platelet slip explains several important basic and clinical observations. If technological advances allow confirmation in a true biologic environment, then our results will likely influence the development of shear-dependent antiplatelet drugs. Also, adding shear rate information, our results provide a direct experimental fluid dynamic foundation for antiplatelet-focused antithrombotic therapy during coronary interventions directed towards higher grade atherosclerotic stenoses.

Feasibility of coronary fractional flow reserve with dual anti-platelet therapy in low risk coronary lesions without systemic anticoagulation-results of the SMART-FFR study

BACKGROUND

Fractional flow reserve (FFR) is used to assess the functional significance of coronary artery stenoses. The optimal anti-thrombotic regimen for FFR has not been studied.

PURPOSE

The goal of this study was to determine whether FFR could be safely performed in Type A coronary lesions, using only upstream dual anti-platelet therapy (DAT) with aspirin and clopidogrel, compared with DAT plus anticoagulation in low risk coronary lesions.

METHODS/MATERIALS

Two hundred patients undergoing FFR for Type A intermediate coronary lesions were blindly randomized into two groups of 100 patients each. Group 1: Upstream DAT, without intra-procedural anti-coagulation and Group 2: Upstream DAT plus intra-procedural bivalirudin. The primary end-points were any coronary thrombotic complications during the index hospital stay, and a composite end-point of any major adverse cardiovascular events (MACE) at 30-days. Secondary end-points included post-procedure troponin levels and TIMI major and minor bleeding scores.

RESULTS

There were no thrombotic complications reported. At 30-days, two MACE occurred in Group 1, and three in Group 2 (p=0.83). No difference was seen in the post-procedure troponin levels (p=0.72), or TIMI bleeding scores study between groups (p=093).

CONCLUSIONS

This initial study evaluating a simplified anti-thrombotic regimen for FFR, suggests that FFR can be performed in low risk coronary lesions using DAT without the need for intra-procedural anticoagulation, with similar results as DAT plus anticoagulation with bivalirudin. Further research in this area is needed to determine the optimal and most cost-effective anti-thrombotic regimen for FFR calculation.

Root canal treatment of a two-rooted C-shaped maxillary first molar: a case report

The most difficult maxillary teeth for endodontic treatment are the maxillary first molars (MFM) due to their complex root canal anatomy. The presence of two roots and C-shaped canals in MFMs has been reported in rare cases. The present case reports root canal treatment of MFM with two roots, where the palatal and buccal roots were joined together in a C-shaped configuration.

Contemporary antiplatelet therapy in patients undergoing percutaneous coronary intervention

The proper use of antiplatelet agents in the cardiac catheterization laboratory is important for ensuring optimal results in patients undergoing percutaneous revascularization. Understanding the mechanisms by which these drugs exerts their effects is important for both interventional and non-interventional cardiologists. The effects of these agents on platelet function can be assessed and monitored using a variety of commercially available laboratory assays but so far these tests have not been adopted in routine clinical practice. Currently, aspirin, thienopyridines and glycoprotein IIb/IIIa inhibitors are the primary types of antiplatelet drugs being utilized. The use of these drugs and of several newer antiplatelet drugs in the treatment of patients undergoing percutaneous revascularization in the cardiac catheterization laboratory will be discussed, especially in the light of the recently published guidelines.

Minimizing femoral artery access complications during percutaneous coronary intervention: a comprehensive review

Major bleeding complications after percutaneous coronary intervention (PCI) increase patient morbidity, prolong the hospital stay and costs, and are associated with reduced survival. Transfemoral access is still preferred at many centers given its familiarity and ease of use and is necessary in cases where large bore access is needed. Multimodality imaging with fluoroscopy, ultrasonography, and angiography can facilitate proper puncture of the common femoral artery. A proper technique (which includes femoral artery puncture and vascular access site closure) associated with adequate pharmacotherapy (both during PCI and peri-procedural, for the treatment of the underlying coronary artery disease) has been shown to reduce the risk of bleeding and vascular complications associated with femoral artery access. Avoiding the use of arterial sheaths >6 French may further reduce the risk of bleeding. Data with vascular closure devices as a bleeding avoidance strategy are evolving but when used appropriately may further reduce the risk of bleeding and vascular access complications, and in this regard are synergistic with bivalirudin. Randomized trials to confirm these recommendations are needed.

Comparison of additional versus no additional heparin during therapeutic oral anticoagulation in patients undergoing percutaneous coronary intervention

Uninterrupted oral anticoagulation (OAC) therapy can be the preferred strategy in patients with atrial fibrillation at moderate to high risk of thromboembolism undergoing percutaneous coronary intervention (PCI). To evaluate the need for additional heparins in addition to therapeutic peri-PCI OAC, we assessed bleeding complications and major adverse cardiac and cerebrovascular events in 414 consecutive patients undergoing PCI during therapeutic (international normalized ratio 2 to 3.5) periprocedural OAC. Patients were divided into those with no (n = 196) and with (n = 218) additional use of periprocedural heparins. No differences in major adverse cardiac and cerebrovascular events (4.1% vs 3.2%, p = 0.79) or major bleeding (1.0% vs 3.7%, p = 0.11) were detected, but access site complications (5.1% vs 11.0%, p = 0.032) were less frequent in those without additional heparins. When adjusted for propensity score, patients with additional heparins had a higher risk of access site complications (odds ratio 2.6, 95% confidence interval 1.1 to 6.1, p = 0.022) without any increased risk of any other adverse event. Analysis of 1-to-1 propensity-matched pairs showed a significantly higher risk of access site complication in patients receiving additional AC (13.1% vs 5.7%, p = 0.049). In conclusion, therapeutic warfarin treatment seems to provide sufficient AC for PCI. Additional heparins are not needed and may increase access site complications.

Comparison of bolus only with bolus plus infusion of bivalirudin in patients undergoing elective percutaneous coronary intervention: a retrospective observational study

BACKGROUND

Anticoagulation therapy during percutaneous coronary intervention (PCI) has been the focus of numerous clinical trials. Low-anticoagulant doses have been successfully used in patients undergoing elective PCI, a situation with low-thrombogenic milieu.

OBJECTIVE

The purpose of the study was to evaluate the safety and efficacy of shorter duration of treatment with bivalirudin in patients undergoing elective PCI and receiving optimal antiplatelet therapy.

METHODS

We compared patients undergoing PCI who received aspirin and clopidogrel loading dose in addition to either conventional bivalirudin dosing (intravenous [IV] bolus of 0.75 + 1.75 mg/kg per h for the duration of PCI; n = 197) or a reduced bivalirudin dose (IV bolus of 0.75 mg/kg; n = 200).

RESULTS

Procedural success was obtained in 100% of cases. The primary end point (in-hospital death, acute myocardial infarction, or need for urgent target vessel revascularization) did not differ between both the groups (6 patients [3%] in the conventional dose group vs 5 patients [2.5%] in the reduced dose group). Major bleeding occurred in 1 patient in the conventional dose group (P = nonsignificant [NS]). Minor bleeding occurred in 4 patients (2%) in the conventional dose group vs 5 patients (2.5%) in the reduced dose group (P = NS) and was mainly due to bleeding at entry site.

CONCLUSION

In patients undergoing elective PCI, using bivalirudin as a bolus only dosing may be as effective and less costly when compared with bolus followed by an infusion for the duration of the intervention. A larger study is needed to confirm our findings.

Safety of same day discharge following percutaneous coronary intervention

BACKGROUND

There is a body of literature reporting the safety of discharging patients the same day as percutaneous coronary revascularisation. Nevertheless, overnight stay continues to be the general standard of care.

METHODS

Over a single calendar year, 130 patients having elective, percutaneous coronary revascularisation were discharged home the day of the procedure with the majority of procedures using radial access. Patients were observed post procedure for six hours and if no problems occurred, discharge was undertaken. The purpose of the study was to assess complications in the 24 hours following discharge.

RESULTS

Within the following 24 hours post discharge, there were no complications reported including bleeding, recurrent ischaemia, or hospitalisation.

CONCLUSION

Same day discharge following elective percutaneous revascularisation appears both efficacious and safe with a low risk of post discharge complications.

Defining the Optimal Degree of Heparin Anticoagulation for Peripheral Vascular Interventions

Background—

The optimal degree of heparin anticoagulation for peripheral vascular interventions (PVIs) has not been defined. We sought to correlate total heparin dose and peak procedural activated clotting time (ACT) with postprocedural outcomes in patients undergoing PVI.

Methods and Results—

We studied 4743 patients who received heparin during PVIs in a regional, multicenter registry. From those, 1246 had recorded peak procedural ACT with the same point-of-care device. Periprocedural and in-hospital outcomes were compared between patients who received a total heparin dose <60 U/kg (n=2161) and ≥60 U/kg (n=2582). Similarly, outcomes were evaluated between groups with a peak procedural ACT <250 seconds (n=855) and ≥250 seconds (n=391). Technical and procedural success as well as intraprocedural thrombotic events did not differ between groups. Patients with heparin dose ≥60 U/kg had a higher rate of postprocedural hemoglobin drop ≥3 g/dL (7.09% versus 5.09%, respectively, P =0.004) and a higher transfusion rate compared with those with heparin dose <60 U/kg (4.92% versus 3.15%, respectively, P =0.002). In multivariate analysis, independent predictors of bleeding requiring transfusion were total heparin dose ≥60 U/kg, ACT ≥250 seconds, female sex, age ≥70 years, prior anemia, prior heart failure, low creatinine clearance, hybrid vascular surgery, rest pain, and below-knee intervention. In propensity-matched, risk-adjusted models and after hierarchical modeling, total heparin dose ≥60 U/kg and ACT ≥250 seconds remained strong predictors of post-PVI drop in hemoglobin ≥3 g/dL or transfusion.

Conclusions—

During PVI, higher total heparin dose (≥60 U/kg) and peak ACT ≥250 seconds were predictors of postprocedural transfusion. The high technical and procedural success in all groups suggests that use of weight-based heparin dosing with a target ACT <250 seconds in PVI may minimize the bleeding risk without compromising procedural success or increasing thromboembolic complications.

Unfractionated heparin during elective PCI: fixed dose or weight adjusted?

INTRODUCTION

To assess two different dosing strategies of unfractionated heparin (UFH) during elective percutaneous coronary intervention (PCI).

AIMS

The optimal dose of heparin during elective PCI in patients with stable angina is unknown. Existing guidelines are based on limited data. We interrogated data from the PCI database. Patients with stable angina undergoing planned transradial PCI for uncomplicated single lesions were included. The main endpoint was troponin I release. We compared a fixed heparin dose (3000 U) UFH to a weight-adjusted dose.

RESULTS

Of 698 patients 244 (35.0%) received fixed dose (3000 U) and 454 (65.0%) 70 U/kg weight-adjusted UFH. There was no significant difference in median troponin between the fixed dose and the weight-adjusted groups; 0.17 ng/mL versus 0.14; P= 0.21. The proportion of troponin positive patients was similar in both groups (61.9% in the fixed dose group vs. 58.1%; P= 0.37). There were no deaths or major ischemic events during hospitalization. There was no bleeding requiring transfusion or delaying hospital discharge.

CONCLUSION

In conclusion, this retrospective observational study of elective transradial PCI demonstrated that a reduced, fixed dose of periprocedural heparin was associated with similar postprocedural troponin levels when compared to a standard weight-adjusted regime. Our study further questions the optimal dose of heparin required during elective PCI and suggests a need for further trials.

ISAR-REACT 3A: a study of reduced dose of unfractionated heparin in biomarker negative patients undergoing percutaneous coronary intervention

AIMS

Although a 140 U/kg dose of unfractionated heparin (UFH) was comparable with bivalirudin in terms of net clinical outcome in the Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment (ISAR-REACT) 3 trial, it was associated with a higher risk of bleeding. We designed this study to assess whether a reduction in the UFH dose from 140 to 100 U/kg is associated with improved net clinical outcome.

METHODS AND RESULTS

A total of 2505 biomarker negative patients undergoing percutaneous coronary intervention (PCI) after clopidogrel pre-treatment received a single bolus of 100 U/kg UFH. The primary endpoint was net clinical outcome-a quadruple endpoint of death, myocardial infarction, urgent target-vessel revascularization within 30 days, or in-hospital REPLACE 2 defined major bleeding. The primary comparison was with the historical UFH group of ISAR-REACT 3 (2281 patients). In a second analysis, we checked for non-inferiority against the historical bivalirudin arm of ISAR-REACT 3 (2289 patients). The incidence of the primary endpoint was 7.3% in the lower UFH dose group compared with 8.7% in the higher UFH dose group [hazard ratio (HR) 0.81; 95% confidence interval (CI) 0.67-1.00; P = 0.045]. The incidence of major bleeding was 3.6% in the lower UFH dose group and 4.6% in the higher UFH dose group (HR 0.79; 95% CI 0.59-1.05; P = 0.11). The lower UFH dose met the criterion of non-inferiority compared with bivalirudin (P < 0.001).

CONCLUSION

In biomarker negative patients undergoing PCI after clopidogrel loading, a reduced dose of 100 U/kg UFH provided net clinical benefit compared with the historical control of 140 U/kg UFH in the ISAR-REACT 3 trial. The benefit was mostly driven by reduction in bleeding.

CLINICAL TRIAL REGISTRATION INFORMATION

URL www.clinicaltrials.gov; Unique identifier NCT00735280.

Catheter thrombosis and percutaneous coronary intervention: fundamental perspectives on blood, artificial surfaces and antithrombotic drugs

Recent reports of catheter thrombosis among patients undergoing percutaneous coronary intervention (PCI) have had a significant impact on the development of new antithrombotic therapies. The overall incidence of this complication is unknown, mainly because of underreporting in contemporary clinical trials of coronary intervention. The etiology and pathophysiology of catheter thrombosis is also poorly understood. Introduction of a catheter or guidewire may not provoke the intense thrombotic response that follows angioplasty or stenting, but factors such as catheter materials and device size, equipment surface properties, flow conditions, procedural time and complexity, as well as the antiplatelet and anticoagulant drugs administered during the procedure influence the likelihood, rate and clinical impact of thrombosis. The crucial role of cellular interactions involving tissue-factor bearing cells and platelets in the process of thrombosis also needs to be critically explored when considering blood contact with an exogenous material. Focusing on the inherently prothrombotic environment of percutaneous coronary intervention, we review the physiologic underpinnings of catheter and guidewire thrombosis, and explore the effect of antithrombotic drugs at the interface between blood and material surfaces. We also propose a clinical classification for the diagnosis and investigation of catheter thrombosis in clinical trials of anticoagulant therapy and PCI.

Efficacy of enoxaparin, certoparin and dalteparin in preventing cardiac catheter thrombosis: an in vitro approach

Owing to its beneficial pharmacological profile, the low-molecular-weight heparin (LMWH) enoxaparin is increasingly being taken as an alternative to UFH in the treatment of ACS with an early invasive strategy and in elective percutaneous coronary interventions (PCI). Insufficient anticoagulation increases the risk of catheter thrombus formation during PCI. The aim of the present study was to test in vitro the hypotheses that (i) inhibiting thrombin or thrombin generation by administering LMWH is a critical intervention in preventing catheter thrombus formation and (ii) other LMWH such as certoparin or dalteparin are as effective as enoxaparin. Blood pre-treated with the anticoagulants of interest was continuously circulated through a guiding catheter by using a roller pump for a maximum experimental period of 60 min or until the catheter became occluded. Overall thrombus weight, anti-Xa activity and electron microscopic features such as deposits of platelets, erythrocytes and fibrin on the catheter surface were quantified as endpoints. All LMWH tested significantly reduced catheter thrombus generation comparable to UFH treatment whereas there was no difference between the specific LMWH with respect to catheter thrombus formation or deposition of platelets, erythrocytes and fibrin. Thrombus generation was found to negatively correlate with anti-Xa activity. The additional use of eptifibatide did not affect thrombus formation. These data suggest that modulating plasmatic coagulation by employing LMWH is critical for preventing catheter thrombus formation and at the same time offer a potential for administering LMWH other than enoxaparin, such as certoparin or dalteparin, in the setting of PCI.