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Drug-eluting stents (DESs) deliver biphasic (early and late) elution of anti-inflammatory compounds. We therefore hypothesized that DESs would be associated with early reductions in inflammatory biomarker release after percutaneous coronary intervention (PCI). A total of 741 patients with non-ST-elevation acute coronary syndrome underwent PCI in the Randomized Trial to Evaluate the Relative PROTECTion against Post-PCI Microvascular Dysfunction and Post-PCI Ischemia among Anti-Platelet and Anti-Thrombotic Agents (PROTECT) Thrombolysis In Myocardial Infarction 30 study of eptifibatide and reduced-dose antithrombin compared with bivalirudin. Serial biomarkers C-reactive protein, troponin, creatine kinase-MB, soluble CD40 ligand, interleukin-6, prothrombin fragment F1.2, and RANTES (regulated on activation, normal T-cell expressed and secreted) were assessed through 24 hours after PCI. DES use was at the investigator's discretion. Patients treated with DESs (n = 665) versus bare metal stents (n = 139) were more likely to have patent arteries before PCI (92.0% vs 86.6%, p = 0.04), Thrombolysis In Myocardial Infarction myocardial perfusion grade 3 (57.9% vs 47.7%, p = 0.033), and the left anterior descending artery as the culprit artery (38.5% vs 18.3%, p <0.001). The increase in C-reactive protein and troponin was lower among patients undergoing DES implantation (median 2.1 vs 3.5 mg/L for C-reactive protein, median 0.11 vs 0.41 ng/ml for troponin), even after adjustment for randomized treatment, clopidogrel before treatment, diabetes mellitus status, epicardial patency, left anterior descending artery location, and myocardial perfusion (p = 0.036 and p = 0.039, respectively). Interleukin-6 was lower with DESs on univariate analysis but not multivariate analysis. Creatine kinase-MB, soluble sCD40 ligand, prothrombin fragment F1.2, and RANTES did not differ by DES use. In conclusion, patients undergoing DES implantation achieved more reductions in periprocedural markers of inflammation and necrosis than patients receiving bare metal stents among those with non-ST-elevation acute coronary syndrome. [ABSTRACT FROM AUTHOR]

Objectives: This study sought to validate the sensitivity and specificity of the Academic Research Consortium's (ARC) classification of stent thrombosis., Background: Classification of stent thrombosis according to ARC criteria has become widely accepted. The criteria have not been validated against an autopsy standard., Methods: An autopsy registry of 139 subjects with prior coronary stenting underwent detailed histopathological analysis to assess for stent thrombosis. Based on clinical data only, cases were adjudicated according to ARC stent thrombosis criteria, including a proposed modification of the possible classification to include death beyond 30 days due only to sudden death or acute ischemia., Results: Autopsy results confirmed 51 cases as positive and 88 as negative for stent thrombosis. Clinical adjudication classified 105 cases as definite (10), probable (31), or possible (64) ARC stent thrombosis. Specificity was high for definite (99%) and definite plus probable (83%) criteria, but sensitivity was poor at 18% and 51%, respectively. Including the possible cases improved sensitivity to 92% but reduced specificity to 34% (58 false positives). The modified possible criteria eliminated 13 false positive cases (specificity = 49%) and was the best approximation of a hypothetical gold standard in a sensitivity analysis if late death represented at least 20% of all stent thrombosis cases., Conclusions: In a selected autopsy sample, restricting ARC stent thrombosis to definite or definite plus probable criteria results in substantial under-reporting of confirmed cases. Inclusion of a modified possible classification may provide the best estimate of late and very late stent thrombosis rates., (Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

An acute inflammatory response occurs following percutaneous coronary and peripheral vascular interventions (PVI), partly mediated by platelet activation. Glycoprotein (GP) IIb-IIIa inhibitors might partially attenuate this inflammation rise in the coronary patient, but data in patients undergoing PVI are lacking. In the Integrilin Reduces Inflammation in Peripheral Vascular Interventions trial (INFLAME), we hypothesized that eptifibatide reduces the acute inflammatory responses following PVI. This is a single-center, randomized, open-label study of intravenous eptifibatide (180 micro/kg bolus x 2, 10 minutes apart, then 2 micro/kg/min infusion over 18 hours) and low-dose unfractionated heparin (60 Units per kg, target activated clotting time (ACT) 200-250 sec) [LDH+I group; n = 21] versus high-dose unfractionated heparin alone (100 Units per kg, target ACT 300-400 sec) [HDH group; n = 21] in patients undergoing iliac and infrainguinal interventions. The primary endpoints of the study were markers of inflammation (soluble CD-40L [sCD-40L], high-sensitivity C-reactive protein [hs-CRP] and interleukin-6 [IL-6]), thrombin generation (Fragment 1.2 [F1.2]), and fibrinogen measured at baseline and postrandomization. Markers were assayed at baseline, postdilatation at 30 minutes, 2 hours, 18 hours, 48 hours and 7 days. Mean platelet inhibition with eptifibatide was 98% (range 92-100%) using the Accumetrics Rapid Platelet Function Assay at 10 minutes after final bolus. After adjusting for baseline values, the mean +/- SE difference in sCD-40L (loge scale), hs-CRP and F1.2 between the LDH+I group and the HDH was not significant. Fibrinogen had significantly higher mean levels at 7 days for the LDH+I group (541.19 mg/dL versus 472.26 mg/dL; p-value = 0.024). IL-6 was more detectable in the LDH+I group compared to the HDH following intervention. We conclude that LDH+I combination did not reduce acute inflammatory responses as compared to HDH in patients undergoing peripheral vascular interventions.

Objectives: The objectives of this double-blind, placebo-controlled, randomized dose-ranging study were 1) to examine the safety and tolerability of tirofiban (MK-383), a new nonpeptide platelet IIb/IIIa receptor antagonist, on a background of intravenous heparin and aspirin therapy; 2) to study the pharmacodynamics and pharmacokinetics of tirofiban; and 3) to evaluate the incidence of adverse cardiac outcomes (urgent repeat revascularization, myocardial infarction and death) with tirofiban versus placebo in a high risk subset of patients undergoing coronary angioplasty., Background: Abrupt vessel closure complicates 4% to 8% of angioplasty procedures. Recent data have suggested that agents that antagonize the platelet glycoprotein IIb/IIIa receptor may reduce the incidence of adverse ischemic outcomes after coronary angioplasty., Methods: Seventy-three patients received tirofiban in three sequential dose panels and 20 patients received placebo. Patients within each panel were randomized to receive either tirofiban or placebo in a 3:1 randomization design. Bolus doses of 5, 10 and 10 microg/kg and continuous infusion (16 to 24 h) doses of 0.05, 0.10 and 0.15 microg/kg per min were administered in panels I, II and III, respectively. Patients received concomitant heparin and aspirin for the angioplasty procedure. Data on patients receiving placebo (heparin and aspirin only) were pooled across panels for comparisons. The pharmacodynamic effect of tirofiban on ex vivo platelet aggregation to 5 micromol/liter adenosine diphosphate (ADP) and bleeding times were measured. Clinical outcomes were assessed in all patients, but the power to detect clinically meaningful differences (a one-third reduction in clinical events) between groups was limited (5%)., Results: Tirofiban was associated with a dose-dependent inhibition of ex vivo ADP-mediated platelet aggregation that was sustained during intravenous infusion and resolved rapidly after drug cessation. Adverse bleeding events, largely related to vascular access site hemorrhage, were slightly increased at the highest dose. Adverse clinical outcomes were infrequent in all patients and were not different among the small number of patients within each group., Conclusions: This study establishes a rational and generally well tolerated dosing regimen for administration of tirofiban as adjunctive therapy in high risk angioplasty patients. The impact of tirofiban on adverse clinical outcomes after angioplasty awaits definition by a larger clinical trial.

The extensive homology between apolipoprotein(a) and plasminogen has led to the hypothesis that the increased risk for atherosclerosis, cardiac disease and stroke associated with elevated levels of apolipoprotein(a) may reflect modulation of fibrinolysis. We have investigated the role of apolipoprotein(a) on clot lysis in transgenic mice expressing the human apolipoprotein(a) gene. These mice develop fatty streak lesions resembling early lesions of human atherosclerosis. Pulmonary emboli were generated in mice by injection, through the right jugular vein, of a human platelet-rich plasma clot radiolabelled with technetium-99m-labelled antifibrin antibodies. Tissue plasminogen activator was introduced continuously via the right jugular vein. Clot lysis, determined by ex vivo imaging, was depressed in mice carrying the apolipoprotein(a) transgene relative to their sex-matched normal littermates. These results directly demonstrate an in vivo effect of apolipoprotein(a) on fibrinolysis, an effect that may contribute to the pathology associated with elevated levels of this protein.

The glycoprotein P-selectin is a cell adhesion molecule of stimulated platelets and endothelial cells, which mediates the interaction of these cells with neutrophils and monocytes. It is a membrane component of cell storage granules, and is a member of the selectin family which includes E-selectin and L-selectin. P-selectin recognizes both lineage-specific carbohydrate ligands on monocytes and neutrophils, including the Lewis x antigen, sialic acid, and a protein component. In inflammation and thrombosis, P-selectin may mediate the interaction of leukocytes with platelets bound in the region of tissue injury and with stimulated endothelium. To evaluate the role of P-selectin in platelet-leukocyte adhesion in vivo, the accumulation of leukocytes within an experimental thrombus was explored in an arteriovenous shunt model in baboons. A Dacron graft implanted within an arteriovenous shunt is thrombogenic, accumulating platelets and fibrin within its lumen. These bound platelets express P-selectin. Here we show that antibody inhibition of leukocyte binding to P-selectin expressed on platelets immobilized on the graft blocks leukocyte accumulation and inhibits the deposition of fibrin within the thrombus. These results indicate that P-selectin is an important adhesion molecule on platelets, mediating platelet-leukocyte binding in vivo, that the presence of leukocytes in thrombi is mediated by P-selectin, and that these leukocytes promote fibrin deposition.

PADGEM (platelet activation-dependent granule-external membrane protein) is a leukocyte receptor of activated platelets that mediates cellular adhesion of platelets to neutrophils and monocytes. To identify the natural ligand on neutrophils and monocytes that interacts with PADGEM, we have evaluated anti-leukocyte antibodies for their ability to block leukocyte-PADGEM binding. Only anti-CD15 antibodies were able to inhibit the binding of neutrophils, monocytes, HL60 cells, and U937 cells to platelets. Anti-CD15 antibodies inhibited the binding of U937 cells to PADGEM-expressing COS cells and to purified PADGEM incorporated into phospholipid vesicles. The CD15 antigen, lacto-N-fucopentaose III (Gal beta 1----4[Fuc alpha 1----3]NAcGlc beta 1----3Gal-beta 1----4Glc), inhibited the interaction of neutrophils or HL60 cells with platelets, whereas lacto-N-fucopentaose I did not; lacto-N-fucopentaose II demonstrated minimal inhibition. Lacto-N-fucopentaose III, and to a lesser extent lacto-N-fucopentaose II, but not lacto-N-fucopentaose I, inhibited the interaction of HL60 cells with COS cells transfected with PADGEM cDNA. CD15, lacto-N-fucopentaose III or Lex, is a component of the PADGEM ligand on neutrophils and monocytes.

Using 111In-labeled autologous platelets, we studied the kinetics of pulmonary platelet deposition and clearance in relation to hemodynamic and structural events during thrombin-induced pulmonary microembolism in rabbits. Autologous platelets were radiolabeled and returned to animals prior to infusion of thrombin (100 units/kg over 15 min) (n = 20) or saline (n = 6). All animals were pretreated with tranexamic acid, an inhibitor of fibrinolysis. Thrombin-treated animals manifested progressive increases in mean pulmonary platelet activity, reaching a maximum of 38% above baseline (p less than .0001), whereas no change was observed in saline-treated controls. Animals that died during, or immediately following, thrombin infusion manifested significantly greater increases in pulmonary platelet uptake (mean 1.55 +/- 0.47 times baseline), compared to surviving animals (1.14 +/- 0.16; p less than .05 survivors vs. nonsurvivors). In surviving animals, following cessation of thrombin, pulmonary platelet activity cleared gradually, with a half-time of approximately 12 min. Thrombin reduced circulating platelet counts (p less than .001), increased mean pulmonary artery pressure (13 +/- 3 mm Hg to 18 +/- 6 mm Hg; p less than .0001), and reduced mean systemic arterial pressure (55 +/- 10 mm Hg to 44 +/- 7 mm Hg; p less than .001). The time courses of these events approximated that of thrombin-induced pulmonary platelet uptake. Furthermore, the increase in pulmonary artery pressure occurred predominantly in the group of animals in which the increase in pulmonary radiolabeled platelet activity exceeded the median value of 20%. Postmortem histology showed extensive pulmonary thrombus extending from small arterial to capillary levels in animals that died during, or immediately following, thrombin infusion, but not in surviving animals. Our findings suggest that platelet aggregation plays an important role in the pathogenesis of hemodynamic change following thrombin-induced pulmonary embolization.