Lower tissue factor inhibition in patients with ST segment elevation than in patients with non ST elevation acute myocardial infarction

Introduction

Mechanisms to explain the different course of coronary thrombosis between ST elevation myocardial infarction (STEMI) and non-STEMI patients remain poorly defined. We hypothesize, however, that STEMI patients may present lower tissue factor plasma inhibition to partly account for their more persistent coronary thrombotic occlusion.

Materials and Methods

Total (t-TFPI ) and free tissue factor plasma inhibitor (f-TFPI), thrombin-antithrombin complex (TAT), plasminogen activator inhibitor 1 (PAI-1), von Willebrand factor (vWF), and fibrinogen were measured on admission and at 3 and 6 months in patients with a first STEMI (n:69) or non-STEMI (n:60). C reactive protein (CRP) was also measured on admission and at 3 months.

Results

STEMI patients showed lower admission levels of t-TFPI (p = 0.001), f-TFPI (p = 0.030) and fibrinogen (p = 0.022), and higher vWF levels (p = 0.005) than non-STEMI whereas TAT, PAI and CRP levels were comparable. At 3 and 6 months VWF, t-TFPI, f-TFPI, and TAT levels declined significantly in the 2 groups (p = 0.002) reaching similar values. CRP levels also declined at 3 months (p = 0.002). Moreover, the rate of cardiac mortality, non fatal MI or stroke during a 6 year follow-up were unrelated to admission coagulation parameters.

Conclusions

The lower inhibition of tissue factor and greater endothelial dysfunction in STEMI than in non-STEMI patients may enhance thrombosis at the culprit lesion and adjacent coronary plaques, and hence, account at least in part for their different pathophysiology. This condition, however, is limited to the acute phase.     

The relationship between aortic aneurysm sac thrombus volume on coagulation, fibrinolysis and platelet activity

Aim

Abdominal aortic aneurysm (AAA) is associated with chronic mural inflammation and a pro-thrombotic diathesis. It has been suggested that both may be related to biologically active intra-sac thrombus. The aim of this study was to examine the relationship between thrombin generation, fibrinolysis, platelet activity and AAA sac thrombus volume.

Methods

30 patients (29 men) of median (IQR) age 75 (71-82) years with an infra-renal AAA > 5.5 cm in antero-posterior diameter were prospectively studied. AAA, lumen and thrombus volumes were calculated using a CT workstation (Vitrea). Plasma thrombin-antithrombin (TAT), plasminogen activator inhibitor (PAI)-1, and soluble (s) P-selectin were measured as biomarkers of coagulation, fibrinolysis and platelet activity, respectively

Results

Median (IQR) AAA total, lumen and thrombus volumes were 188 (147-247) cm³, 80 (54.3-107) cm³ and 97.6 (63-127) cm³ respectively.TAT levels were significantly higher (median, QR, 7.15 [4.7-31.3] μg/L, p = < 0.001) and sP-selectin levels significantly lower (median, IQR, 80.5 [68-128] ng/ml, p = < 0.0001) than the normal range. PAI-1 levels (median, IQR, 20.9 [8.4-50.7] ng/ml) were normal. There was no correlation between AAA thrombus volume and PAI-1 (r = − 0.25, p = 0.47), sP-Selectin (r = 0.26, p = 0.43) or TAT plasma levels (r = − 0.21, p = 0.54).

Conclusion

The present study confirms that patients with AAA demonstrate haemostatic derangement, but the extent of the haemostatic derangement does not correlate with AAA sac thrombus volume.     

P2Y12 platelet reactivity after thrombolytic therapy for ST-segment elevation myocardial infarction

Introduction

Thrombolysis, as reperfusion therapy for ST segment elevation myocardial infarction (STEMI), induces a pro-thrombotic status with enhanced platelet activity; this study aims to evaluate P2Y12 platelet reactivity and response to clopidogrel in the post-thrombolysis scenario.

Materials and Methods

Observational, prospective study, including consecutive patients with elective angiography after thrombolytic therapy for STEMI. Every patient received antiplatelet therapy with loading doses of 250 mg aspirin and 300 mg clopidogrel on admission followed by 100 mg aspirin and 75 mg clopidogrel daily. P2Y12-dependent platelet reactivity (expressed in P2Y12-Reaction Units, PRU) was assessed with VerifyNow® device on admission, daily after thrombolysis and pre-angiography.

Results

41 patients fulfilled the inclusion criteria. Median time between thrombolysis and angiography was 2,5 days (IQR 1,8-4,1). Post-treatment platelet reactivity (PPR) showed poor correlation with time on clopidogrel treatment (r2 = 0.04) and reached a maximum value of 274 ± 84 PRU during the first 24 h after thrombolysis (Day + 1 determination). After this, values showed a progressive reduction until the point of angiography (249 ± 82 PRU), without significant differences between consecutive time-points (p = 0,549).Inhibition of platelet aggregation (IPA) assessed as a percentage of P2Y12 receptor blockage was poor, increasing gradually from 0 ± 4% on admission to 11 ± 6% the day of the angiography (p = 0,001). 71,4% of patients showed PPR ≥ 208 PRU during angiography.

Conclusions

Platelet reactivity, as assessed by post-treatment P2Y12 mediated reactivity, is heightened after thrombolytic therapy during STEMI management. In this scenario, standard doses of clopidogrel did not achieve significant inhibition of ADP-mediated platelet reactivity.     

Platelet activation in patients with peripheral vascular disease: reproducibility and comparability of platelet markers

Background

Many markers of platelet activation have been described but their reproducibility and comparability in patient populations are poorly defined.

Objectives

We sought to compare markers of platelet and monocyte activation with platelet-monocyte aggregates, a proposed gold standard of in vivo platelet activation, and assess their reproducibility in patients with peripheral arterial disease: a population with substantial platelet activation, inflammation and risk of thrombotic events.

Patients/Methods

Thirty patients with peripheral vascular disease attended on two occasions to permit within-day and between-day comparisons. In vivo platelet and monocyte activation were determined by flow-cytometric quantification of platelet-monocyte aggregation, platelet surface expression of P-selectin and CD40L, platelet-derived microparticles, and monocyte surface expression of CD40 and CD11b. Plasma concentrations of platelet-derived microparticles, soluble P-selectin and CD40L were measured by enzyme-linked immunosorbant assays.

Results

Platelet-monocyte aggregation (36.7 ± 7.86%), and platelet surface expression of P-selectin (5.8 ± 1.65%) and CD40L (3.3 ± 1.45%) demonstrated comparable within-day (mean difference ± co-efficient of reproducibility; 0.9 ± 15.4%, 0.21 ± 1.65% and 0.2 ± 2.8% respectively) and between-day reproducibility (2.0 ± 12.4%, 0.10 ± 2.25% and 0.9 ± 6.4% respectively). Platelet-monocyte aggregates correlated well with other platelet (r = 0.30-0.50, P < 0.02) and monocyte (r = 0.27-0.47, P < 0.03) activation markers. Flow cytometric and assay quantified platelet-derived microparticles showed poorer reproducibility (co-efficient of reproducibility > 40).

Conclusions

In patients with peripheral arterial disease, measurements of platelet-monocyte aggregates have good reproducibility and consistently reflect other markers of platelet and monocyte activation.     

Evidence of increased platelet reactivity in the first six months after acute ST segment elevation myocardial infarction

Introduction

Platelets play a crucial role in the pathogenesis of acute coronary syndromes. Accordingly, previous studies showed increased platelet reactivity on admission in these patients. In this study we assessed platelet reactivity at short-medium term follow-up in patients with ST-segment elevation acute myocardial infarction (STEMI).

Materials and methods

Fifty-nine patients (58 ± 11 years, 45 men), treated with primary angioplasty, were studied 1 month after STEMI. Thirty-five patients were retested at 6 months. Twenty matched patients with stable coronary artery disease served as controls. Platelet reactivity was assessed by flow cyometry at rest and at peak exercise, with and without adenosine diphosphate (ADP) stimulation, by measuring monocyte-platelet aggregates (MPAs) and glycoprotein IIb/IIIa (CD41) expression in the MPA gate, and CD41 and fibrinogen receptor (PAC-1) expression in the platelet gate.

Results

Compared to controls, basal MPAs and CD41 in the MPA gate were higher in STEMI patients both at 1 month (p = 0.001 and p = 0.002, respectively) and at 6 months (p = 0.03 and p = 0.01, respectively). Basal CD41 and PAC-1 expression was also higher in STEMI patients at the two assessments compared to controls (P < 0.001 for both). Exercise induced a similar increase in platelet reactivity in patients and controls. ADP induced a higher increase in CD41 platelet expression in STEMI patients compared to controls both at 1 and 6 months (P < 0.001).

Conclusion

Platelet reactivity is increased in the first 6 months after STEMI. The persistence of increased platelet reactivity in this time period may play a role in the early recurrence of coronary events after STEMI.     

Inflammatory and thrombotic markers in patients with ST-elevation myocardial infarction treated with thrombolysis and early PCI: A NORDISTEMI substudy

Introduction

Both pharmacological and invasive treatment might influence the inflammatory and pro-thrombotic responses observed in acute ST-elevation myocardial infarction (STEMI). We aimed to study whether circulating levels of inflammatory and pro-thrombotic markers differ in STEMI patients treated with early angioplasty compared to standard therapy following thrombolysis. Furthermore, we wanted to study if levels of markers were related to infarct size.

Materials and Methods

This was a substudy of the NORwegian study on DIstrict treatment of ST-Elevation Myocardial Infarction (NORDISTEMI), in which STEMI patients treated with thrombolysis were randomized to early invasive or standard therapy. Fasting blood samples were collected in the morning 3 days and 3 months after onset of STEMI. Commercially available ELISA methods were used for determination of inflammatory and pro-thrombotic markers. Infarct size was assessed by SPECT after 3 months.

Results

246 patients were included in this substudy. At 3 days, levels of prothrombin fragment 1 + 2 and D-dimer were higher in the early invasive compared to the standard treatment group, whereas levels of soluble CD40 ligand were lower (p < 0.01 for all). No other differences between groups were found in any of the measured markers. Significant, although weak correlations were found between Day 3 levels of C-reactive protein, interleukin-6, prothrombin fragment 1 + 2 and D-dimer, and infarct size assessed by SPECT after 3 months.

Conclusions

An early invasive strategy following thrombolysis for STEMI was associated with higher subacute levels of D-dimer and prothrombin fragment 1 + 2, and lower levels of soluble CD40 ligand than standard treatment. Further studies are needed to establish the relation between these changes and clinical outcome.The NORDISTEMI was registered at www.clinicaltrials.gov, NCT00161005.     

The long-term prognostic value of multiple biomarkers following a myocardial infarction

Introduction

We assessed the long-term prognostic value of multiple cardiac biomarkers after an acute myocardial infarction (MI) in order to evaluate a multimarker approach to risk stratification.

Material and methods

Blood samples from 298 patients hospitalized with a myocardial infarction were subsequently tested for NT-proBNP, hsCRP, MMP-9, PAPP-A, MPO, sCD40L and FM.

Results

During the median follow-up period of 45 months, 83 patients suffered at least one TnT- positive event. In the unadjusted analysis NT-proBNP predicted future ACS or cardiac death with a hazard ratio (HR) of 1.83 (95% confidence interval (CI), 1.17 − 2.87, p = 0.009) in Q4 as compared to the three lower quartiles (Q1-3). However, NT-proBNP was dependent on chronic heart failure and HDL-cholesterol in the stepwise multivariable model, with a hazard ratio (HR) in Q4 of 1.38 (95% CI, 0.82 − 2.33, p = 0.229). The other biomarkers were not found to be related to the primary event following the index MI.

Conclusion

In a patient population consisting of 298 subjects hospitalized with a MI, a multimarker approach with NT-proBNP, hsCRP, MMP-9, PAPP-A, MPO, sCD40L and FM rendered no additional prognostic information beyond conventionally used stratification tools in the acute phase. However, this does not preclude clinical valuable prognostic information by a biomarker such as NT-proBNP.     

Antiplatelet effects of antidepressant treatment: A randomized comparison between escitalopram and nortriptyline

Introduction

Depressive disorders have been identified as independent risk factors for coronary heart disease. The present study (i) compared platelet function of depressed patients with that of healthy controls, (ii) analysed possible aggregability changes during 3 months of treatment with antidepressants, and (iii) sought to assess different effects of escitalopram and nortriptyline on platelet aggregation.

Methods

Blood samples of 91 major depressed patients and 91 healthy controls were analysed with whole blood aggregometry in a case-control setting. Depressed patients were randomized to two groups treated either with escitalopram (n = 47) or nortriptyline (n = 44). Platelet aggregation was studied on days 0, 1, 3, 7, 14, 21, 84 of continuing medication and was determined in response to adenosine diphosphate (ADP) and collagen.

Results

Platelet aggregation induced by ADP was increased among depressive patients compared with that of healthy controls (26%, p = 0.006). With antidepressant treatment, changes in platelet aggregation remained comparable in both groups at early time points (d1 to 21). In contrast, at day 84, patients with antidepressive response revealed significant differences in both medication groups: Patients receiving escitalopram showed a 23% decrease of ADP induced aggregation (p = 0.03) and a 15% decrease of collagen induced aggregation (p = 0.03). With nortriptyline the increase in impedance was reduced by 29% after ADP induction (p = 0.046).

Conclusion

Depressed patients have higher ex vivo platelet aggregation that may contribute to increased cardiovascular morbidity. After three months of antidepressant treatment with either escitalopram or nortriptyline, platelet aggregation was significantly reduced in antidepressant responders, irrespective of the antidepressant medication type.     

Evaluation of platelet function and pharmacological platelet inhibition in patients with myeloproliferative disorders using multiple electrode aggregometry

Background

The aim of this study was to describe platelet aggregation characteristics by multiple electrode aggregometry (MEA) and to evaluate MEA for its potential to detect platelet dysfunction and response to anti-aggregatory drugs in patients with myeloproliferative disorders (MPD).

Methods

We compared the platelet response to arachidonic acid (ASPI test), adenosine diphosphate (ADP test) and thrombin receptor activating peptide (TRAP test) in hirudin-anticoagulated blood of 55 patients with polycythaemia vera and essential thrombocythaemia and 75 controls.

Results

Comparing MPD patients and controls no statistically significant difference indicative of platelet dysfunction was found in MPD patients. Analysis of covariance revealed platelet- and leukocyte count as a significant influencing factor on MEA function. Furthermore we could demonstrate that ASA and clopidogrel treatment results in a statistically significant lower ASPI (Controls: p < 0.0001, MPD: p < 0.0001) and ADPtest value (MPD: p = 0.00125) compared to untreated patients thereby validating the method for monitoring of anti-aggregatory therapy.

Conclusion

In this study MEA was confirmed as a valid method for monitoring of ASA and clopidogrel treatment in patients with MPD and normal control subjects. The platelet and leukocyte count were identified as major influencing factors on MEA aggregation tests both in MPD patients and controls. No functional platelet abnormalities were detected in MPD patients.     

Platelet protease-activated receptor 1 and membrane expression of P-selectin in pulmonary arterial hypertension

Introduction

Pulmonary arterial hypertension (PAH) is frequently associated with thrombotic events, particularly involving the pulmonary microcirculation at sites of vascular injury. We therefore decided to analyse protease-activated receptor 1 (PAR1), a key element in the activation of human platelets by thrombin, in PAH patients in stable clinical condition.

Methods

Using flow cytometry, we analyzed platelet PAR1 density, PAR1-mediated exposure of P-selectin and the formation of platelet-leukocyte aggregates in 30 PAH patients aged 11 to 78 years (median 50.5 years). The control group consisted of 25 healthy subjects with the same age range as patients.

Results

In patients, total platelet PAR1 density and uncleaved PAR1 density correlated negatively with platelet count (r² = 0.33 and r² = 0.34 respectively, p < 0.0015). In patients with a low platelet count (< 150 × 10⁹ platelets/L), both densities were increased relative to controls (82% and 33% respectively, p < 0.05). Thrombin peptide-induced platelet exposure of P-selectin was directly related to total and uncleaved PAR1 density (respectively, r² = 0.33 and r² = 0.29, p < 0.0025) and increased in subjects with low platelet count (46% versus those with normal platelet count, p < 0.05). Patients with low platelet count had decreased in vitro thrombin-induced formation of platelet-leukocyte aggregates (57% decrease versus controls, p < 0.05).

Conclusions

There seems to be a subpopulation of PAH patients with increased propensity to thrombotic events as suggested by increased platelet PAR1 expression and PAR-mediated surface exposure of P-selectin associated with decreased platelet count.     

Depressive symptoms, perceived social support, and prothrombotic measures in patients with venous thromboembolism

Introduction

Psychosocial factors have been associated with both a prothrombotic state and an increased risk of venous thromboembolism (VTE). We examined the relation of depressive symptoms and social support with D-dimer, an integrative measure of enhanced coagulation activity, and several additional prothrombotic measures in patients with VTE.

Methods

We studied 173 patients with a previous deep venous thrombosis and/or pulmonary embolism (mean age ± SD 45 ± 14 years, 55% men). Clinical and lab assessments took place ≥ 3 months after VTE and ≥ 1 month after discontinuation of oral anticoagulants. The patients rated depressive symptoms and social support by validated questionnaires.

Results

After adjusting for sociodemographic and medical covariates, interactions emerged between depressive symptoms and social support for D-dimer (p = 0.012) and aPTT (p = 0.002). As opposed to patients with high levels of social support, those with low levels of social support showed a direct association of depressive symptoms with D-dimer (r = 0.19, p = 0.014) and an inverse relationship with aPTT (r = -0.14, p < 0.09). Depressive symptoms were associated with levels of thrombin-antithrombin complex (r = 0.19, p = 0.016). Greater social support was associated with prolonged aPTT (r = 0.16, p = 0.046). There were no significant associations of depressive symptoms and social support with D-dimer, fibrinogen, FII:C, FV:C, FVII:C, FVIII:C, FX:C, INR, and thrombin time.

Conclusions

Depressive symptoms are associated with enhanced coagulation activity in patients with VTE, particularly so in those who perceive low levels of social support. Conversely, high levels of social support may contribute directly and through buffering the effect of depressive symptoms to attenuated clotting activity in VTE patients.     

Aspirin insensitive thromboxane generation is associated with oxidative stress in type 2 diabetes mellitus

Introduction

Aspirin (ASA) irreversibly inhibits platelet cyclooxygenase-1 (COX-1) leading to decreased thromboxane-mediated platelet activation. The effect of ASA ingestion on platelet activation, thromboxane generation, oxidative stress and anti-oxidant biomarkers was studied in type 2 diabetes mellitus (DM).

Material and methods

Baseline and post-ASA samples (100/325 mg x 7 days) were obtained from 75 DM patients and 86 healthy controls for urinary 11-dehydro-thromboxane B2 (11dhTxB2), 8-iso-prostaglandin-F2α (8-isoPGF2α) and serum sP-Selectin, nitrite (NO₂^-), nitrate (NO₃^-) and paraoxonase 1 (PON1) activity.

Results

Compared to baseline controls, baseline DM had higher mean levels of 11dhTxB2 (3,665 ± 2,465 vs 2,450 ± 1,572 pg/mg creatinine, p = 0.002), 8-isoPGF2α (1,457 ± 543 vs 1,009 ± 412 pg/mg creatinine, p < 0.0001), NO₂^- (11.8 ± 7.3 vs 4.8 ± 5.3 μM, p < 0.0001), NO₃^- (50.4 ± 39.3 vs 20.9 ± 16.7 μM, p < 0.0001) and sP-Selectin (120.8 ± 56.7 vs 93.0 ± 26.1 ng/mL, p = 0.02), and the same held for post-ASA levels (p < 0.0001). ASA demonstrated no effect on 8-isoPGF2α, NO₂^-, NO₃^-, sP-Selectin or PON1 activity in either DM or controls. Post ASA inhibition of urinary 11dhTxB2 was 71.5% in DM and 75.1% in controls. There were twice as many ASA poor responders in DM than in controls (14.8% and 8.4%) based on systemic thromboxane reduction. Urinary 8-isoPGF2α excretion was greater in DM ASA poor responders than good responders (p < 0.009).

Conclusions

This suggests that oxidative stress may maintain platelet function irrespective of COX-1 pathway inhibition and/or increase systemic generation of thromboxane from non-platelet sources.     

Activated factor XI and tissue factor in chronic obstructive pulmonary disease: links with inflammation and thrombin generation

Introduction

Increased cardiovascular mortality and risk of venous thromboembolism are serious extra-pulmonary complications of chronic obstructive pulmonary disease (COPD). Previously, circulating active tissue factor (TF) and factor XIa (FXIa) have been reported to be associated with acute coronary syndromes.

Objective

To measure plasma FXIa and active TF, prothrombin fragment 1.2 (F1.2), and markers of systemic inflammation (C-reactive protein [CRP], interleukin-6 [IL-6], tumor necrosis factor α [TNFα] and matrix metalloproteinase 9 [MMP-9]) in 60 patients with documented stable COPD free of previous thromboembolic events.

Methods

In-house clotting assays using inhibitory monoclonal antibodies against FXIa and TF.

Results

FXIa was detected in 9 (15%) and TF activity in 7 (11.7%) COPD patients. Subjects positive for FXIa and/or TF (n = 10; 16.7%) had higher F1.2 (median [interquartile range], 398 [216] vs 192 [42] pM, p < 0.000001), fibrinogen (5.58 [2.01] vs 3.97 [2.47] g/L, p = 0.0007), CRP (14.75 [1.20] vs 1.88 [2.95] mg/L, p < 0.000001), IL-6 (8.14 [4.74] vs 2.45 [2.24] pg/mL, p = 0.00002), and right ventricular systolic pressure (47 [15] vs 38 [12] mmHg, p = 0.023), and lower vital capacity (66 [15] vs 80 [17] % predicted, p = 0.04) than COPD patients without detectable FXIa and TF. COPD severity was not associated with the presence of circulating FXIa and active TF.

Conclusions

This is the first study to show that active FXIa and TF are present in stable COPD patients, who exhibit enhanced systemic inflammation and thrombin generation. Our findings suggest a new prothrombotic mechanism which might contribute to elevated risk of thromboembolic complications in COPD.     

Markers of endothelial and platelet activation are associated with high on-aspirin platelet reactivity in patients with stable coronary artery disease

Introduction

Aspirin inhibits the cyclooxygenase-1 (COX-1) mediated thromboxane A2 synthesis. Despite COX-1 inhibition, in patients with coronary artery disease (CAD), platelets can be activated through other mechanisms, like activation by thrombin.

Materials and Methods

At baseline in this cross-sectional substudy of the ASCET trial, 1001 stable CAD patients, all on single aspirin treatment, were classified by the PFA100® method, as having high on-aspirin residual platelet reactivity (RPR) or not. Markers of hypercoagulability, endothelial and platelet activation as related to RPR, were evaluated to explore the potential mechanisms behind high on-aspirin RPR.

Results

Altogether, 25.9% (n = 259) of the patients were found to have high on-aspirin RPR. S-thromboxane B₂ levels were very low and did not differ between patients having high on-aspirin RPR or not. Patients with high on-aspirin RPR had significantly higher levels of von Willebrand Factor (vWF) (124 vs 100%, p < 0.001, platelet count (236 vs 224 × 10⁹/l, p = 0.008), total TFPI (68.4 vs 65.5 ng/ml, p = 0.005) and ß-thromboglobulin (ß-TG) (33.3 vs 31.3 IU/ml, p = 0.041) compared to patients with low on-aspirin RPR. No significant differences between the groups were observed in levels of endogenous thrombin generation (ETP), pro-thrombin fragment 1+2 (F1+2), D-dimer, soluble TF (sTF) or P-selectin (all p > 0.05).

Conclusions

The high on-aspirin RPR as defined by PFA100® seems not to be due to increased thrombin activity as evaluated with ETP, sTF, F1+2 or D-dimer. The elevated levels of platelet count, ß-TG, TFPI and especially vWF might be explained by increased endothelial and platelet activation in these patients.     

Genetic determinants of response to aspirin: appraisal of 4 candidate genes

Introduction

Intersubject variability in platelet response to aspirin could be related to genetic factors that regulate platelet enzymes or receptors. This study evaluates the impact of the selected polymorphisms in the COX-1 gene, the CYP5A1 gene, the P2RY1 receptor gene, and the GPIIbIIIa receptor gene on platelet response to aspirin and risk of suffering from major adverse cardiovascular and cerebrovascular events (MACCE).

Materials and methods

192 Caucasian patients with stable coronary artery disease treated with daily aspirin were recruited and followed for 3 years. Platelet aggregation was measured by light transmission aggregometry with arachidonic acid (1.6 mM) and adenosine diphosphate (5, 10 or 20 μM) used as agonists. Genotyping was performed by standard PCR methods.

Results

Arachidonic acid-induced platelet aggregation was unaffected by the COX-1 22C/T and by the Pl^A1/A2 polymorphisms. However, carriers of the 1622 G/G genotype of the P2RY1 gene had significantly higher levels of arachidonic acid-induced platelet aggregation compared with non-carriers (AA 2.0%, AG 2.0% vs. GG 9.0%, p = 0.047). Carrying the 1622 G/G genotype increased the risk of inadequate platelet response to aspirin, defined as arachidonic acid-induced aggregation ≥ 20%, by a factor of 8.5 (1.4 - 53.3, p = 0.022) and the risk of 3-year MACCE by a factor of 7 (1.4 - 34.7, p = 0.017).

Conclusion

The 1622A/G mutation of the P2RY1 gene could contribute to inadequate platelet response to aspirin and is associated with an increased risk of suffering from MACCE.     

Platelet activation and endogenous thrombin potential in pre-eclampsia

Introduction

Platelets and the coagulation system may be involved in the pathogenesis of pre-eclampsia. We investigated whether platelet and coagulation activation markers, are elevated in pre-eclampsia.

Materials/methods

Case-control study in which activated platelets, platelet-monocyte/ neutrophil aggregates, platelet microparticles (measured by flow cytometry) and four markers of thrombin generation capacity (endogenous thrombin potential (ETP), peak height, lag time and time to peak) using the Calibrated Automated Thrombogram system were assessed in pregnant women of similar gestational age with (n = 46) and without (n = 46) pre-eclampsia, and in healthy non-pregnant women (n = 42).

Results

The percentage of, CD62P+ platelets (p = 0.013), CD62P+ platelet microparticles (p = 0.029) and platelet-monocyte aggregates (p = 0.019) were significantly higher in women with pre-eclampsia than the pregnant controls. Both groups of pregnant women had significantly higher ETP and peak height (p  < 0.001) than the healthy non pregnant group and the women with pre-eclampsia had significantly higher ETP and peak height (p < 0.001) than the normotensive pregnant controls.

Conclusion

In the most comprehensive laboratory analysis to date, we found evidence of both platelet and coagulation activation in women with pre-eclampsia.     

Stent implantation in the superficial femoral artery: Short thrombelastometry-derived coagulation times identify patients with late in-stent restenosis

Introduction

The mechanisms of restenosis, the recurrence of luminal narrowing, are complex and incompletely understood to date. Thrombin, the pivotal enzyme in haemostasis, presumably contributes to the formation of in-stent restenosis (ISR). It was therefore the aim of our study to investigate whether blood coagulation/thrombin generation plays a critical role in the formation of ISR in peripheral artery disease patients with stent angioplasty in the superficial femoral artery.

Materials and Methods

We aimed to examine in this retrospective study whether patients with high-degree restenosis (50-75% lumen diameter reduction, n = 20) are in a hypercoaguable state implying enhanced readiness to generate thrombin compared to patients with low-degree restenosis (< 50% lumen diameter reduction, n = 14).

Results

The coagulation tests calibrated automated thrombography, activated partial thromboplastin time, platelet aggregation, platelet adhesion, fibrinogen, and microparticles’ procoagulant activity did not indicate a different coagulation status in the two patient groups. However, the thrombelastometry-derived value Coagulation Time (CT) was significantly shorter in the high-degree restenosis group (p = 0.012), indicating a hypercoagulable state of patients with high-degree restenosis. Under our experimental conditions, CTs shorter than 444.5 s identify patients at high risk (sensitivity = 95%) for luminal narrowing.

Conclusions

Our study supports the assumption that blood coagulation/thrombin generation plays a critical role in the development of ISR in peripheral arteries after stent insertion and that the thrombelastometry-derived CT might be a suitable value to identify peripheral artery disease patients at risk for development of high-degree in-stent restenosis in the superficial femoral artery.     

Reduced platelet response to aspirin in patients with coronary artery disease and type 2 diabetes mellitus

Introduction

Diabetes mellitus is complicated by accelerated atherosclerosis, resulting in an increased risk of coronary artery disease (CAD) and thrombosis. Despite the proven benefits of aspirin, previous studies indicate a reduced cardiovascular protection from aspirin in diabetic patients. We aimed to investigate whether diabetes mellitus influenced the platelet response to aspirin in patients with CAD.

Materials and Methods

Platelet aggregation and activation were evaluated during aspirin treatment in 85 diabetic and 92 non-diabetic patients with CAD. Adherence to aspirin was carefully controlled. All patients had CAD verified by coronary angiography and were taking 75 mg non-enteric coated aspirin daily.

Results

Diabetic patients showed significantly higher levels of platelet aggregation compared to non-diabetic patients evaluated by VerifyNow^® Aspirin (p = 0.03) and Multiplate^® aggregometry using arachidonic acid (AA) 0.5 mM (p = 0.005) and 1.0 mM (p = 0.009). In addition, platelet activation determined by soluble P-selectin was significantly higher in diabetics compared to non-diabetics (p = 0.005). The higher AA-induced aggregation was associated with higher levels of HbA_1c. Compliance was confirmed by low levels of serum thromboxane B₂ (below 7.2 ng/mL). Diabetics had significantly higher levels of serum thromboxane B₂ (p < 0.0001).

Conclusions

Diabetic patients with CAD had significantly higher levels of both platelet aggregation and activation compared to non-diabetic patients with CAD despite treatment with the same dosage of aspirin. These findings may partly explain the reduced cardiovascular protection from aspirin in diabetic patients.     

Incidence and predictive factors of symptomatic thrombosis related to peripherally inserted central catheters in chemotherapy patients

Introduction

The incidence of symptomatic catheter-related deep vein thrombosis (DVT) in cancer patients remains unclear and there is a lack of reliable data on the risk factors of PICC-related DVT.

Materials and Methods

We performed a retrospective cohort study of consecutive cancer patients who received an ultrasound guided PICC line for the administration of chemotherapy. Univariable and multivariable logistic regression analyses were performed to identify risk factors for symptomatic PICC-related DVT.

Results

In total, 340 cancer patients obtained PICC lines for the administration of chemotherapy. Of these patients, 19 (5.6%; 95% CI: 3.6-8.6) developed symptomatic PICC-related DVT. Factors previously associated with catheter-related DVT, including side of catheter placement, lumen size, tip location, need for repositioning, and number of insertion attempts, were not significant determinants in our analysis. Patients with diabetes were three times more likely to develop PICC-related DVT (OR 3.0, p = 0.039), while the presence of COPD and metastatic cancer also increased the odds (OR 3.3, p = 0.078 and OR 2.3, p = 0.083 respectively). Diabetes remained a significant risk factor after adjustment for effect of metastases and COPD (OR 3.175, p = 0.039). Further, the presence of metastases was a significant predictor (OR 3.34, p = 0.024) in our multivariable model.

Conclusions

Symptomatic PICC-related DVT are frequent in cancer patients receiving chemotherapy. Previously described factors associated with catheter-related thrombosis were not predictive of PICC-related DVT in our study. Diabetes, advanced disease and COPD appear to increase the risk of developing PICC-related DVT in chemotherapy patients.     

Endogenous thrombin potential (ETP) in plasma from patients with AMI during antithrombotic treatment

Background

The beneficial impact of warfarin in preventing new events after AMI is well established. Decrease in thrombin generation seems to be the key element in anticoagulant treatment.

Objectives

The aims were to investigate the effect of warfarin and platelet inhibition on thrombin generation, assessed by the endogenous thrombin potential (ETP), and study the relation between coagulation parameters and ETP in patients with AMI.

Patients/Methods

In the present sub-study of the WARIS II trial, patients with AMI were randomly assigned to treatment with aspirin 160 mg/d (n = 57), aspirin 75 mg/d and warfarin (INR 2.0-2.5) (n = 68) or warfarin (INR 2.8-4.2) (n = 61). Fasting blood samples were collected from patients at discharge from hospital and after 6 weeks treatment.

Results

Correlation analyses showed that both ETP and peak thrombin levels were significantly correlated with Factor VII Ag (r = 0.38 and 0.36 respectively, p < 0.01 for both) and with F1+2 (r = 0.26 and 0.23 respectively, p = 0.01 for both) at baseline. Antithrombotic treatment for 6 weeks caused a highly significant inhibition of ETP in patients treated with warfarin (− 28% ± 5%, p < 0.001), and patients treated with aspirin/warfarin (− 24% ± 8%, p = 0.04). Similarly, peak thrombin levels were reduced in patients treated with warfarin (− 18% ± 7%, p = 0.049) and aspirin/warfarin (− 19% ± 5%, p = 0.029), whereas an increase (12% ± 4%, p = 0.029) occurred during aspirin treatment alone. F1+2 levels decreased by 64% and 58% in the warfarin and aspirin/warfarin groups, respectively (p = 0.001 for both).

Conclusions

In patients with AMI, warfarin significantly reduced the endogenous thrombin generation and the potential to generate thrombin in plasma ex vivo, whereas aspirin alone had no effect on thrombin generation in vivo or ex vivo, assessed by ETP.