hirudin and Heart-Diseases

Heparin-induced thrombocytopenia (HIT) remains under-recognized despite its potentially devastating outcomes. It begins when heparin exposure stimulates the formation of heparin-platelet factor 4 antibodies, which in turn triggers the release of procoagulant platelet particles. Thrombosis and thrombocytopenia that follow comprise the 2 hallmark traits of HIT, with the former largely responsible for significant vascular complications. The prevalence of HIT varies among several subgroups, with greater incidence in surgical as compared with medical populations. HIT must be acknowledged for its intense predilection for thrombosis and suspected whenever thrombosis occurs after heparin exposure. Early recognition that incorporates the clinical and serologic clues is paramount to timely institution of treatment, as its delay may result in catastrophic outcomes. The treatment of HIT mandates an immediate cessation of all heparin exposure and the institution of an antithrombotic therapy, most commonly using a direct thrombin inhibitor. Current "diagnostic" tests, which primarily include functional and antigenic assays, have more of a confirmatory than diagnostic role in the management of HIT. Special attention must be paid to cardiac patients who are often exposed to heparin multiple times during their course of treatment. Direct thrombin inhibitors are appropriate, evidence-based alternatives to heparin in patients with a history of HIT, who need to undergo percutaneous coronary intervention. As heparin remains one of the most frequently used medications today with potential for HIT with every heparin exposure, a close vigilance of platelet counts must be practiced whenever heparin is initiated.

Topics: Anticoagulants; Antithrombins; Cardiac Surgical Procedures; Heart Diseases; Heparin; Hirudins; Humans; Immunoassay; Monitoring, Physiologic; Peptide Fragments; Practice Guidelines as Topic; Recombinant Proteins; Risk Factors; Thrombocytopenia

Antithrombotic therapy is a crucial component of interventional cardiology and currently involves the administration of both anticoagulant and antiplatelet agents. The implementation of standard dual or triple antiplatelet therapies has allowed percutaneous coronary intervention (PCI) with stent implantation to become the treatment of choice in most patients with acute coronary syndromes (ACS), particularly in patients with ST-segment elevation myocardial infarction. However, the combined use of antithrombotic agents increases the bleeding risk associated with coronary intervention, which is a concern due to the increasing evidence that bleeding complications are associated with a higher risk of ischaemic events and death. The shortcomings of currently available anticoagulant drugs have promoted the ongoing development of new, powerful anticoagulant agents that have both efficacy in the setting of PCI and a reduced risk of bleeding; one of these classes of agents targets the thrombin molecule, a key factor in the coagulation cascade, and belongs to the class of anticoagulants known as direct thrombin inhibitors (DTIs). Bivalirudin, a synthetic peptide, is a DTI with unique, favourable pharmacological properties that include predictable linear pharmacokinetics. Bivalirudin was approved as an anticoagulant in patients undergoing routine PCI in 2000 by the FDA (in 2004 in Europe and Australia) and more recently in patients with ACS undergoing PCI. The pharmacological properties of bivalirudin, along with current indications for its use, are discussed in this review, with a focus on the major completed and ongoing clinical trials with bivalirudin.

Topics: Animals; Cardiology; Fibrinolytic Agents; Heart Diseases; Hemostatics; Hirudins; Humans; Peptide Fragments; Randomized Controlled Trials as Topic; Recombinant Proteins; Thrombin

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.

Topics: Aged; Aged, 80 and over; Angioplasty, Balloon, Coronary; Antithrombins; Coronary Artery Disease; Diabetes Complications; Drug Therapy, Combination; Female; Heart Diseases; Heparin; Hirudins; Humans; Incidence; Male; Myocardial Infarction; Peptide Fragments; Platelet Glycoprotein GPIIb-IIIa Complex; Postoperative Complications; Postoperative Hemorrhage; Recombinant Proteins; Renal Insufficiency; Treatment Outcome

The Randomized Evaluation in PCI Linking Angiomax to Reduced Clinical Events (REPLACE)-2 trial is one of the largest acute randomized controlled trials evaluating the efficacy of two anticoagulant strategies during contemporary urgent or elective percutaneous coronary intervention (PCI). The direct thrombin inhibitor, bivalirudin, with provisional use of glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitor was compared to low-dose unfractionated heparin (UFH) plus planned GP IIb/IIIa inhibitor. At 30-day follow-up, the primary quadruple composite endpoint (death, myocardial infarction (MI), urgent repeat revascularization, or in-hospital major bleeding) occurred in 9.2% of patients in the bivalirudin group versus 10.0% of patients in the UFH plus GP IIb/IIIa inhibitor group. The secondary triple composite endpoint (death, MI, urgent repeat revascularization) occurred in 7.6% of patients in the bivalirudin group compared with 7.1% of patients in the UFH plus GP IIb/IIIa inhibitor group. Both endpoints met formal statistical criteria for noninferiority to UFH plus GP IIb/IIIa inhibitor. By imputed comparison from historic GP IIb/IIIa trials between bivalirudin versus UFH alone, REPLACE-2 demonstrated that bivalirudin was superior to UFH alone with respect to the quadruple and triple composite endpoints. Furthermore, bivalirudin plus provisional GP IIb/IIIa blockade was associated with a significant reduction in in-hospital bleeding (2.4% vs. 4.1%; p < 0.001). At 6 months' follow-up, there was no significant difference in rates of death, MI, or revascularization between the two groups. Furthermore, there was no evidence that the early, nonsignificant 0.5% excess non-Q-wave MI in the bivalirudin group translated into later mortality. There was a trend toward decreased mortality at 6 months in the bivalirudin arm (0.95% vs. 1.35%; p = 0.148). The relative efficacy of bivalirudin versus UFH plus GP IIb/IIIa inhibitor was similar in several high-risk subgroups, including patients with diabetes mellitus or prior MI, women, the elderly (age > 65 years), and patients undergoing PCI of bypass grafts. Bivalirudin represents an exciting alternative to UFH plus GP IIb/IIIa inhibitor in patients undergoing urgent and elective PCI with similar suppression of ischemic events, fewer bleeding complications, and the potential for greater cost savings and ease of administration.

Topics: Adult; Aged; Anticoagulants; Clinical Trials as Topic; Double-Blind Method; Female; Heart Diseases; Heparin; Hirudins; Humans; Male; Middle Aged; Peptide Fragments; Platelet Glycoprotein GPIIb-IIIa Complex; Recombinant Proteins; Thrombin; Time Factors; Treatment Outcome

We compared the effects of hirudin and heparin on thrombin generation and activity among 350 patients with acute coronary syndromes enrolled in the GUSTO-IIb trial.. We obtained blood at baseline; at 4, 8, and 24h into infusion; at drug termination; and 6 and 24h after termination. We assayed for thrombin activity (fibrinopeptide A, activated protein C, thrombin-antithrombin complex), thrombin generation (prothrombin fragment 1.2), and platelet activation (platelet factor 4). Median baseline fibrinopeptide A and platelet factor 4 levels were elevated. Thrombin formation tended to increase with hirudin and decrease with heparin; by 8h into infusion, thrombin formation was significantly less for heparin (P<0.01). Most patients showed reduced thrombin activity and platelet activation during infusion of either agent. Hirudin-assigned patients had significantly lower fibrinopeptide A levels during infusion. Six h post-termination, both groups had increased thrombin activity. Thrombin formation was increased in heparin patients (P<0.0001), significantly more than with hirudin (P=0.005). Higher values of haemostasis markers tended to be associated with poorer 30-day outcomes.. Although hirudin did not prevent generation of new thrombin, it appeared to inhibit thrombin activity more than did heparin and produced slower increases in thrombin formation after discontinuation. The reelevation of thrombotic markers after stopping intravenous antithrombin therapy and the tendency toward increased thrombotic events with post-treatment increases in marker levels suggest an ongoing, clinically significant prothrombotic state. These results raise the possibility of improving on current antithrombotics by preventing thrombin generation and thrombin activity and by sustained suppression of the prothrombotic state.

Topics: Acute Disease; Aged; Blood Coagulation; Double-Blind Method; Female; Fibrinolytic Agents; Heart Diseases; Hemostasis; Heparin; Hirudin Therapy; Hirudins; Humans; Male; Middle Aged; Syndrome; Thrombin; Treatment Outcome

Bivalirudin is a direct thrombin inhibitor that is used as a procedural anticoagulant during percutaneous coronary interventions and cardiac surgery for patients with heparin-resistant thrombosis or heparin-induced thrombocytopenia. There is a robust literature describing its safety and efficacy in adults; however, its use in the pediatric population is relatively rare, with dosing extrapolated from adult data. In this case report, we describe a 4-year-old with complex congenital heart disease and history of heparin-induced thrombocytopenia who required bivalirudin dose uptitration during cardiac catheterization.

Topics: Antithrombins; Cardiac Catheterization; Child, Preschool; Heart Diseases; Hirudins; Humans; Male; Peptide Fragments; Recombinant Proteins; Treatment Outcome

Topics: Anticoagulants; Cardiopulmonary Bypass; Child; Heart Diseases; Heparin; Hirudins; Humans; Peptide Fragments; Recombinant Proteins

We report the case of a 27-year-old woman with signs of heparin-induced thrombocytopenia and thrombosis (HITT) and left heart failure presenting for urgent implantation of a left ventricular assist device (LVAD). HITT can occur in 4.2-6.1% of patients with LVADs. If the patient remains hemodynamically stable, implantation can be delayed for several months until the heparin/PF-4 antibodies decline allowing the use of heparin on cardiopulmonary bypass, However, in most cases related to cardiogenic shock, surgery cannot be delayed. We present the case of a patient who underwent implantation of a HeartMate II LVAD and discuss management strategy using bivalirudin during cardiopulmonary bypass.

Topics: Adult; Anticoagulants; Antithrombins; Cardiopulmonary Bypass; Combined Modality Therapy; Female; Heart Diseases; Heart Ventricles; Heart-Assist Devices; Heparin; Hirudins; Humans; Peptide Fragments; Prosthesis Implantation; Recombinant Proteins; Thrombocytopenia; Thrombosis; Treatment Outcome

This study sought to investigate if the efficacy of bivalirudin monotherapy is similar to heparin plus GP IIb/IIIa inhibition in patients with acute coronary syndromes (ACS) treated with clopidogrel following diagnostic angiography.. Prior trials have demonstrated that peri-procedural bivalirudin therapy confers similar efficacy as heparin plus GP IIb/IIIa inhibitors, while lowering the risk of bleeding complications in ACS patients undergoing percutaneous coronary interventions (PCI). However, the incidence of adverse ischemic events post-PCI appeared to be higher in patients receiving bivalirudin without adequate pretreatment with clopidogrel.. Using the 2004/2005 Cornell Angioplasty Registry, we evaluated 980 consecutive patients undergoing urgent PCI for UA/NSTEMI who were treated with either bivalirudin or UFH plus GP IIb/IIIa inhibitor. We excluded patients who were on chronic clopidogrel therapy or received clopidogrel pretreatment prior to angiography. All patients received a clopidogrel load (≥300-mg dose) immediately before or after the PCI. Long-term all-cause mortality was obtained for 100% of patients, with a mean follow-up of 24.6 ± 7.7 months.. Of the 980 study patients, 461 (47.0%) were treated with bivalirudin and 519 (53.0%) patients received UFH plus GP IIb/IIIa inhibitor. DES were used in 88% of PCI; 45% of patients presented with NSTEMI. The incidence of in-hospital death (0.4% vs. 0.2%, P = 0.604), post-procedural MI (6.9% vs. 5.4%, P = 0.351), and MACE including death, stroke, emergent CABG/PCI, and MI (7.6% vs. 5.8%, P = 0.304) were similar in patients treated with bivalirudin versus UFH plus GP IIb/IIIa inhibitors, respectively. The incidence of in-hospital stent thrombosis was similar (0.7% vs. 0%, P = 0.104), while major (0.9% vs. 2.9%, P = 0.034) and minor bleeding (10.4% vs. 18.9%, P < 0.001) was reduced in the bivalirudin-treated group. By two-years of follow-up, after propensity-score adjusted multivariate Cox regression analysis, there was no significant difference in long-term mortality between the two groups (HR 1.18; 95%CI 0.64-2.19, P = 0.598).. In patients presenting with ACS and receiving clopidogrel treatment after angiography (before or within 30 min of PCI), peri-procedural bivalirudin monotherapy suppresses acute and long-term adverse events to a similar extent as does UFH plus GP IIb/IIIa inhibitors, while significantly lowering the risk of bleeding complications.

Topics: Acute Coronary Syndrome; Aged; Aged, 80 and over; Angioplasty, Balloon, Coronary; Antithrombins; Chi-Square Distribution; Clopidogrel; Coronary Angiography; Drug Administration Schedule; Drug Therapy, Combination; Female; Heart Diseases; Hemorrhage; Heparin; Hirudins; Hospital Mortality; Humans; Kaplan-Meier Estimate; Logistic Models; Male; Middle Aged; New York City; Odds Ratio; Peptide Fragments; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Propensity Score; Proportional Hazards Models; Recombinant Proteins; Registries; Retrospective Studies; Risk Assessment; Risk Factors; Stroke; Ticlopidine; Time Factors; Treatment Outcome

Topics: Acute Coronary Syndrome; Angioplasty, Balloon, Coronary; Antithrombins; Clopidogrel; Coronary Angiography; Drug Administration Schedule; Drug Therapy, Combination; Heart Diseases; Hemorrhage; Heparin; Hirudins; Hospital Mortality; Humans; Peptide Fragments; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Recombinant Proteins; Risk Assessment; Risk Factors; Stroke; Ticlopidine; Time Factors; Treatment Outcome

Prevention of valve thrombosis in patients after prosthetic mechanical heart valve replacement and heparin-induced thrombocytopenia (HIT) is still an open issue. The aim of the present in-vitro study was to investigate the efficacy of argatroban and bivalirudin in comparison to unfractionated heparin (UFH) in preventing thrombus formation on mechanical heart valves. Blood (230 ml) from healthy young male volunteers was anticoagulated either by UFH, argatroban bolus, argatroban bolus plus continuous infusion, bivalirudin bolus, or bivalirudin bolus plus continuous infusion. Valve prostheses were placed in a newly developed in-vitro thrombosis tester and exposed to the anticoagulated blood samples. To quantify the thrombi, electron microscopy was performed, and each valve was weighed before and after the experiment. Mean thrombus weight in group 1 (UFH) was 117 + 93 mg, in group 2 (argatroban bolus) 722 + 428 mg, in group 3 (bivalirudin bolus) 758 + 323 mg, in group 4 (argatroban bolus plus continuous infusion) 162 + 98 mg, and in group 5 (bivalirudin bolus plus continuous infusion) 166 + 141 mg (p-value <0.001). Electron microscopy showed increased rates of thrombus formation in groups 2 and 3. Argatroban and bivalirudin were as effective as UFH in preventing thrombus formation on valve prostheses in our in-vitro investigation when they were administered continuously. We hypothesise that continuous infusion of argatroban or bivalirudin are optimal treatment options for patients with HIT after mechanical heart valve replacement for adapting oral to parenteral anticoagulation or vice versa.

Topics: Anticoagulants; Arginine; Diagnostic Techniques, Cardiovascular; Drug Therapy, Combination; Feasibility Studies; Heart Diseases; Heart-Assist Devices; Heparin; Hirudins; Humans; In Vitro Techniques; Infusion Pumps; Male; Peptide Fragments; Pipecolic Acids; Recombinant Proteins; Sulfonamides; Thrombin; Thrombocytopenia; Thrombosis

The Clinical Trials described in this article were presented at the Hotline and Clinical Trial Update Sessions of the European Society of Cardiology Congress held in September 2007 in Vienna, Austria. The sessions chosen for this article represent the scope of interest of Cardiovascular Drugs and Therapy. The presentations should be considered preliminary, as further analyses could alter the final publication of the results of these studies. PROSPECT evaluated echocardiographic criteria for optimal selection of patients with moderate to severe heart failure who may benefit from cardiac resynchronisation therapy, however concluded that no single echocardiographic measure can be recommended. EVEREST found that tolvaptan, a vasopressin V(2) antagonist, resulted in early weight reduction and improvement of dyspnoea in patients with acute heart failure, but lacked long term improvement. In ARISE, the anti-oxidant succinobucal did not affect the primary outcome in high risk cardiovascular patients, but improved the combination of cardiovascular death, myocardial infarction and stroke, and diabetic control in diabetics. ALOFT showed that the addition of the renin inhibitor aliskiren to an ACE inhibitor or ARB and a beta-blocker leads to favourable effects on neurohormonal actions in heart failure. FINESSE markedly improved coronary patency before PCI with half-dose reteplase/abciximab in STEMI patients, however without significantly improving short-term outcome. The Prague-8 Study evaluated whether routine clopidogrel administered >6 h pre-angiography would be a safe way to achieve therapeutic drug levels in case a follow-up intervention would be considered immediately, but appeared not justified because of bleeding complications. CARESS in MI showed that high risk patients with evolving STEMI who undergo thrombolytic therapy should undergo PCI early after the thrombolysis. Finally, the ACUITY trial found that in moderate or high risk Non ST elevation ACS patients triaged to PCI, coronary artery bypass graft (CABG) surgery, or medical management, bivalirudin, with or without associated GPIIb/IIIa inhibitor therapy, resulted in a marked reduction of bleeding at 30 days whilst preserving the ischemic and mortality benefit at 1 year follow up.

Topics: Abciximab; Acute Coronary Syndrome; Amides; Antibodies, Monoclonal; Benzazepines; Clinical Trials as Topic; Clopidogrel; Electrocardiography; Europe; Fumarates; Heart Diseases; Heart Failure; Hirudins; Humans; Immunoglobulin Fab Fragments; Myocardial Infarction; Peptide Fragments; Probucol; Recombinant Proteins; Ticlopidine; Tolvaptan

Only few reports exist addressing the problem of temporary pacemaker leads associated with thromboembolic disease. We report the case of a 67-year-old patient who required a temporary transfemoral pacemaker due to AV block grade III. The patient developed extensive right atrial and ventricle thrombus formation attached to the pacing wire, as well as venous thrombosis at the insertion site due to heparin-induced thrombocytopenia type II (HIT type II). After short-term thrombolysis with 1 mg rt-PA/kg b.w. complete resolution of all clots could be shown by B-mode sonography and transthoracic, as well as transesophageal echocardiography.

Topics: Aged; Anticoagulants; Chondroitin Sulfates; Dermatan Sulfate; Drug Combinations; Fibrinolytic Agents; Heart Atria; Heart Diseases; Heart Ventricles; Heparin; Heparinoids; Heparitin Sulfate; Hirudin Therapy; Hirudins; Humans; Pacemaker, Artificial; Thrombocytopenia; Thrombolytic Therapy; Thrombosis; Tissue Plasminogen Activator

The presence of residual mural thrombus may predispose to recurrent thrombotic events in acute coronary syndromes. The purpose of this study was to evaluate the effects of antithrombotic and antiplatelet agents on a preformed, fresh mural thrombus during growth of thrombus.. A fresh mural thrombus was formed by perfusing severely injured arterial wall with porcine blood for 5 minutes at a shear rate of 1690 s(-1). Thrombus formation was measured by morphometric analysis (mm2/mm). The average size of a mural thrombus formed in 5 minutes was 0.14+/-0.03 mm2/mm. Progression of thrombus growth within 10 minutes triggered by the preformed thrombus was evaluated in pigs treated with r-hirudin (1 mg/kg per hour i.v.) as a probe for thrombin, high-dose heparin (250 IU/kg per hour i.v.), moderate-dose heparin (100 IU/kg per hour), moderate-dose heparin (100 IU/kg per hour) plus aspirin, aspirin alone (5 mg/kg i.v.), and placebo. Hirudin was associated with a significant decrease (48%) of mural thrombus area and significantly reduced growth of thrombus (0.07+/-0.01), even compared with the highest dose of heparin (0.15+/-0.03), although at lower levels of anticoagulation. Inhibition of growth of thrombus with heparin was dose dependent, showing an inverse correlation of thrombus area with mean plasma heparin concentrations (r=.77, P=.0001). Thrombus size was unchanged by aspirin (0.29+/-0.07) compared with controls (0.28+/-0.07).. Direct inhibition of thrombin activity with r-hirudin completely inhibits growth of thrombus, causes dissolution of a preexisting mural thrombus, and is more effective at lower levels of anticoagulation than the highest dose of heparin at shear rates typical of a moderate coronary stenosis.

Topics: Animals; Aspirin; Drug Evaluation, Preclinical; Drug Synergism; Drug Therapy, Combination; Fibrinolytic Agents; Heart Diseases; Hematocrit; Heparin; Hirudin Therapy; Hirudins; Partial Thromboplastin Time; Platelet Aggregation Inhibitors; Platelet Count; Recombinant Proteins; Swine; Thrombin; Thrombolytic Therapy; Thrombosis

A serious retroperitoneal bleeding occurred in a 56-year-old male patient receiving unfractionated heparin due to multiple pulmonary embolism. After reducing the heparin dose, the patient developed a new pulmonary embolism and a large thrombus in the right atrium. Concomitantly, the platelet count dropped to a value of 29 g/l. Heparin-induced thrombocytopenia (HIT) was confirmed by a functional assay, the heparin-induced platelet activation (HIPA) assay, whereas the results of a platelet factor 4/heparin complex ELISA were repeatedly negative. This indicated that the patient's HIT antibodies were directed towards an antigen other than platelet factor 4/heparin complexes. For treatment of the atrial thrombus, an ultra-low-dose lysis with rt-PA (2 mg/h, intravenously) was administered for a period of 52 h, overlapping with systemic treatment with recombinant hirudin (Lepirudin, Refludan, 0.06-0.14 mg/kg/h intravenously). The aim was to enhance lysis of the thrombus without increasing the haematoma, and at the same time keep the risk of fulminant pulmonary embolism due to thrombus fragmentation as low as possible. The cardiac thrombus disappeared within 48 h, without new signs of pulmonary embolism. Platelet counts normalized within nine days.

Topics: Anticoagulants; Arrhythmias, Cardiac; Autoimmune Diseases; Heart Atria; Heart Diseases; Hemorrhage; Heparin; Hirudin Therapy; Hirudins; Humans; Male; Middle Aged; Phenprocoumon; Plasminogen Activators; Pulmonary Embolism; Recombinant Proteins; Retroperitoneal Space; Thrombocytopenia; Thrombolytic Therapy; Thrombosis; Tissue Plasminogen Activator; Vena Cava Filters

Platelet-thrombus formation is a complication of arterial wall deep injury by balloon angioplasty that may lead to acute arterial occlusion and may contribute to restenosis.. Because common platelet-inhibitor drugs with a heparin bolus (100 units/kg) may be effective in inhibiting platelet-thrombus formation after arterial angioplasty, these were compared with a bolus of heparin alone (control), the specific thrombin inhibitor hirudin (1.0 mg/kg), and saline (hirudin control) in normal pigs after angioplasty of the common carotid arteries. In the presence of deep arterial wall injury (injury exposing the media), indium-111-labeled platelet deposition (x 10(6)/cm2) was 68.8 +/- 12.3 and 48.1 +/- 16.9 in the control animals. This was significantly reduced by pretreatment with low-dose aspirin (1 mg/kg/day), by high-dose aspirin (20 mg/kg/day) plus dipyridamole, and especially by thrombin inhibition with hirudin. Treatment regimens with aspirin alone (20 mg/kg/day), dipyridamole alone, or sulfinpyrazone were ineffective. Likewise, the incidence of mural thrombosis was 75% and 80% in deeply injured arteries of controls and was significantly reduced to 46% with aspirin plus dipyridamole, 25% with low-dose aspirin, and 0% with hirudin. The incidence of mural thrombosis was unchanged with high-dose aspirin (69%), dipyridamole (90%), or sulfinpyrazone (92%). This mural thrombosis could not be identified by angiography. In the presence of mild injury (deendothelialization), platelet deposition was low (less than 10 x 10(6)/cm2, a single layer) and was not changed by any therapy, including hirudin.. These therapies do not affect platelet adhesion to deeply or mildly injured artery. These data suggest a greater role for thrombin inhibition than with thromboxane or cyclooxygenase inhibition in the pathogenesis of platelet-rich mural thrombosis after deep injury during angioplasty. Antithrombotic therapy for arterial thrombosis by thrombin inhibition appears promising.

Topics: Angioplasty, Balloon; Animals; Arteries; Aspirin; Dipyridamole; Fibrinolytic Agents; Heart Diseases; Heparin; Hirudins; Platelet Aggregation Inhibitors; Swine; Thrombosis