Changes of hemostasis, endogenous fibrinolysis, platelet activation and endothelins after percutaneous transluminal coronary angioplasty in patients with stable angina

Association between changes in platelet reactivity during elective percutaneous coronary intervention and periprocedural myocardial infarction: A pilot study

BACKGROUND

High platelet reactivity before percutaneous coronary intervention (PCI) reportedly increases the risk of PCI-related myocardial infarction (PMI) following elective PCI. We conducted a pilot study to evaluate changes in platelet reactivity during PCI and their association with the incidence of PMI.

METHODS

In total, 133 consecutive patients undergoing elective PCI after pretreatment with dual antiplatelet therapy for at least 7 days were prospectively enrolled. Platelet reactivity was measured by the VerifyNow^® assay (International Technidyne Corporation, Edison, NJ, USA) immediately before and after PCI.

RESULTS

Platelet reactivity significantly increased from 177.3 ± 53.4 P2Y12 reaction units (PRU) before PCI to 203.4 ± 52.8 PRU immediately after PCI (p < 0.001). Absolute changes in platelet reactivity were significantly greater in patients with than without PMI (32.4 ± 29.0 vs. 21.2 ± 24.8 PRU, respectively; p = 0.021). In the multivariable logistic regression analysis, the absolute change in PRU was an independent predictor of the incidence of PMI. Receiver operating characteristic curve analysis of the change in PRU during PCI for discriminating PMI showed a sensitivity, specificity, and the cut-off value of 46%, 76%, and 37 PRU, respectively (area under the curve = 0.607, p = 0.0235). When the patients were divided into two groups, namely a greater (change in PRU ≥ 37) and smaller (change in PRU < 37) increase group, the incidence rate of PMI was significantly higher in the greater than smaller increase group (59.1% vs. 34.8%, respectively; p = 0.008). Additional exploratory analyses by intracoronary imaging demonstrated that the proximal reference lumen area in the greater increase group was significantly smaller than that in the smaller increase group (6.5 ± 2.4 vs. 7.7 ± 3.1 mm², respectively; p = 0.032).

CONCLUSION

An increase in platelet reactivity after elective PCI is possibly associated with PMI. This finding should be validated by a larger-scale study.

Coagulation, Fibrinolysis, and Platelet Activation Following Open Surgical or Percutaneous Angioplasty Revascularization for Symptomatic Lower Limb Chronic Ischemia

Introduction:

Critical limb ischemia (CLI) is associated with a prothrombotic diathesis that involves a complex balance between the coagulation and fibrinolytic systems. Knowledge of this is essential when considering revascularization procedures but is often overlooked. The aim of this review is to summarize the available literature and provide an overview of the effects of lower limb angioplasty and open surgical revascularization on coagulation, fibrinolysis, and platelet activation.

Methods:

A MEDLINE and EMBASE search was conducted between 1973 and 2014 for articles relating to the effects of revascularization for patients with CLI on the fibrinolytic and coagulation pathways. Studies with a small cohort of patients (<5) were rejected.

Results:

Many of the studies included in this analysis had small cohorts. Multiple markers were assessed across the published literature including von Willebrand factor, tissue factor, prothrombin fragments 1 and 2, platelets, soluble platelet selectin, plasminogen activator inhibitor 1, tissue plasminogen activator, and thrombin–antithrombin complex. Percutaneous intervention causes an exaggerated prothrombotic and a disturbed fibrinolytic effect. Surgery seems to cause a similar prothrombotic derangement with reduced fibrinolysis and platelet hyperactivity, but this appears to be maintained for a considerable amount of time postoperatively.

Conclusion:

There is a sparse amount published on the effects of the coagulation and fibrinolytic systems in patients undergoing intervention for CLI. Much of these studies are small, historical, and completely heterogeneous, making it difficult to draw meaningful conclusions. The literature does identify a prothrombotic state in patients with CLI, which appears to be exacerbated by any form of intervention and prolonged in those having surgery. Understanding this may allow us to tailor the intervention offered to patients and prevent limb loss.

Reduced thrombin generation and soluble P-selectin after intravenous enoxaparin during PCI

PURPOSE

The objective of our study was to identify changes in the coagulation and serum concentration of soluble P-selectin (sP-sel) after i.v. bolus of 0.75 mg/kg enoxaparin in a group of 33 patients during PCI.

METHODS AND RESULTS

As compared to baseline, i.v. enoxaparin increased anti -Xa activity and FIIa inhibition together with APTT and thrombin time tests within 20 min, that persisted for 60 min. At 6 h, the results of all tests had returned to baseline. In contrast, the level of prothrombin fragments (F1 + 2) decreased persistingly for a period of 6 h (baseline 1.19 ± 0.42 nmol/l, after 20 min 1.03 ± 0.46 nmol/l, after 60 min 1.06 ± 0.43 nmol/l, after 6 h 0.95 ± 0.40 nmol/l, p < 0.001 vs. baseline for all values). In addition, i.v. enoxaparin decreased serum sP-sel level (baseline 111.80 ± 37.05 ng/ml, after 20 min 87.80 ± 33.17 ng/ml, after 60 min 86.45 ± 29.15 ng/ml, after 6 h 92.24 ± 31.34 ng/ml, p < 0.001 vs. baseline value for all). sP-sel level mildly correlated with both F Xa inhibition (r = -0.275, p < 0.05) and F1 + 2 level (r = 0.274, p < 0.05).

CONCLUSION

Intravenous enoxaparin induced target F Xa inhibition (>0.6 IU/ml) for 60 min in 82% of study patients. During the 6 h of monitoring, a decrease of thrombin generation (F1 + 2) and sP-selectin levels were observed.

Plasminogen and plasmin activity in patients with coronary artery disease

OBJECTIVE

While coronary artery disease (CAD) is associated with disturbances of the plasma fibrinolytic system, the nature of these disturbances is not fully defined. Fibrinolysis is regulated by plasmin, whose production is mediated by plasminogen activator conversion of plasminogen (Plg) to plasmin. The cascade is modulated by feedback loops that include Plg activator inhibitor 1 (PAI-1). Molecular interactions with Plg kringle domains play an important role in regulating plasmin production and its modulation of fibrinolysis. We hypothesized that interactions of tissue plasminogen activator (tPA) with Plg kringle domains regulates plasmin levels in patients with stable CAD.

METHODS

Plasma was collected from patients (n = 33) with an angiographically significant CAD and controls (n = 18) with angiographically established normal or minimally diseased arteries. Plasmin activity, tPA activity, and plasma levels of Plg, PAI-1, uPA, and tPA were determined.

RESULTS

CAD patients had 1.7-fold greater plasmin activity (P = 0.02) that correlated with 1.5-fold higher tPA activity when compared to controls. Epitope mapping of Plg domains showed Plg differences in epitope exposure between the two groups. Plasma from CAD patients had 50% less (P < 0.001) detectable kringle 4 and 48% less (P = 0.007) detectable kringles 1-3.

CONCLUSIONS

Based on detectable differences in Plg, we conclude that in patients with stable CAD, Plg complexed with tPA exists in a conformation that enables increased tPA activity and Plg conversion to plasmin.

Existence of a Clinically Relevant Interaction between Clopidogrel and HMG-CoA Reductase Inhibitors? Re-evaluating the Evidence

Clopidogrel is an inactive prodrug, which requires activation by the cytochrome P450 3A4 system in order to exert its antiplatelet action. Some statins (atorvastatin, lovastatin and simvastatin) also requires metabolism by the cytochrome P450 3A4 system. From a theoretical point of view, a clinical relevant interaction may exist between clopidogrel and cytochrome P450 3A4 metabolized statins. Nine studies have investigated the existence of this potential interaction. Seven studies have used results based on platelet function as surrogate endpoints and two studies have dealt with objective clinical events including mortality, acute myocardial infarction and stroke. However the studies have yielded conflicting results. This controversy is primarily caused by substantial differences in study design and methods used for assessment of the antiaggregatory effect of clopidogrel. Most studies have included too few patients, and there appears to be no consensus regarding the definition of and optimal way of measuring the platelet inhibitory effect of clopidogrel. Therefore an adequately powered prospective study, ensuring elimination of identified possible confounders and with the use of a well-defined surrogate ex vivo parameter should be performed.

Hemostatic markers with bolus versus prolonged heparin after carotid artery stenting

BACKGROUND

The evolving technique of carotid stenting (CS) requires optimal antithrombotic strategies to reduce periinterventional thromboembolic risk. In animal models of balloon injury, tissue factor (TF) was shown to be the major procoagulant of the atherosclerotic plaque mediating prolonged procoagulant activity.

METHODS

We analyzed TF and TF-dependent hemostatic markers before and 2, 6 and 24 h after CS with two antithrombotic drug regimens. Group A (n=20) received prolonged unfractionated heparin (UFH) for 18-20 h starting at intervention next to aspirin and thienopyridine. In group B (n=16), single bolus UFH was administered next to combined antiplatelet therapy. Natural anticoagulants were determined at baseline.

RESULTS

Patients with symptomatic and asymptomatic cerebrovascular disease did not differ in plasma TF levels. Furthermore, no statistically significant difference for TF, TFPI/Xa-complex and prothrombin fragment F1.2 was observed between bolus and prolonged heparin treatment. No significant change was found in time course for these parameters. Two patients (5.5%; one in each treatment group) suffered periinterventional minor stroke associated with increased levels of F1.2 and TFPI/Xa-complex. Both were resistant to activated protein C (APC ratio<1.9) due to heterozygous factor V Leiden mutation.

CONCLUSIONS

No significant activation of the TF pathway was seen with both antithrombotic regimens suggesting that single bolus UFH combined with antiplatelet therapy is generally sufficient to control TF-dependent procoagulant activity after CS. However, patients with resistance to activated protein C may be at increased periinterventional stroke risk.

[Treatment of acute myocardial infarct with ST segment elevation with a combination of fibrinolytic therapy and abciximab]

BACKGROUND

According to current knowledge, the best way to treat the acute myocardial infarction with ST elevation is primary transluminal coronary angioplasty, which can be performed only in the best equipped tertiary cardiology centers. As it was known that atherothrombosis wais the essence of the acute coronary syndrome we wanted to examine the efficacy and safety of combined therapy of tissue plasminogen activator and glycoprotein IIbIIIa platelet receptor antagonist abciximab.

METHODS

The case is reported of combined abciximab and accelerate schedule of t-PA reperfusion therapy in a young patient with the extensive anterior acute myocardial infarction. Activated partial thromboplastin time and platelet count were regularly measured during therapy.

RESULTS

The combination of these two drugs did not cause any complication in our patient. According to early noninvasive parameters, successful reperfusion was achieved. Postinfarction period was without complications. Coronary angiography was performed 15 days after and was without pathological findings. Eighteen months later the event patient had neither chest pain, nor other complaints with slightly reduced R waves in middle precordial leads and hypokinesis of anterior apical segment of the left ventricle showing the signs of important systolic function impairment.

CONCLUSION

Controlled studies are needed to prove the safety and the benefit of such combined reperfusion therapy and to show which kind of treatment is appropriate in every case considering the patient conditions and the facilities of coronary care unit.

Monitoring of platelet function in the setting of glycoprotein IIb/IIIa inhibitor therapy

The role of the platelet in the pathogenesis of acute coronary syndromes is clearly established. In addition, the beneficial effects of oral and intravenous platelet inhibitor therapies were demonstrated in multiple, large, randomized clinical trials. However, despite these advances, current antiplatelet therapy fails to prevent coronary events in a substantial proportion of patients. One possible explanation for this phenomenon is that antiplatelet medications are administered without monitoring of the response to therapy. For example, oral antiplatelet therapy is administered as a standard dose for all patients, while intravenous inhibitors of the platelet glycoprotein (GP) IIb/IIIa receptor are dosed based on patient body weight. A major limitation of measuring platelet function has been that no practical test exists. The historic gold standard, bleeding time, was a very crude measure of platelet function with limited clinical utility. The current "gold standard," turbidimetric aggregometery, requires a central laboratory and is cumbersome to perform. Fortunately, a number of new tests with rapid turnaround time can be performed at the patient's bedside. This article discusses the details regarding the performance, advantages, disadvantages, and available data related to clinical use of each test in populations with coronary disease and patients treated with antiplatelet therapy.

In vitro bleeding test with PFA-100-aspects of controlling individual acetylsalicylic acid induced platelet inhibition in patients with cardiovascular disease

OBJECTIVES

This study investigated the usefulness and practicability of a platelet function analyzer (PFA-100(TM), DADE-Behring, Germany) to determine individual platelet inhibition in patients treated with acetylsalicylic acid (ASA).

BACKGROUND

Patients with coronary artery disease (CAD) routinely and during angioplasty (PTCA) receive standard doses of ASA to avoid acute coronary syndromes and abrupt vessel closures without information of the individual efficacy of platelet inhibition.

METHODS

With the PFA-100(TM) a standardized bleeding time is measured. Whole-blood anticoagulated with 3.2% sodium citrate is aspirated through a capillary ( solidus in circle 200 microm) and through an aperture ( solidus in circle 147 microm). The time until occlusion of the aperture (closure time, CT) by a stable platelet plug induced by shear stress, collagen and epinephrine (COLL/EPI-CT) or shear stress, collagen and adenosine 5'-diphosphate (COLL/ADP-CT) is determined. To examine the usefulness of the PFA-100(TM) as a rapid bedside test and the individual effect of ASA, closure time was measured in healthy individuals (n=17), in patients with stable CAD (n=19) and in patients undergoing PTCA (n=8).

RESULTS

Patients with stable CAD and regular medication with 100 mg ASA per day for at least 3 month showed shorter COLL/ADP-CT in comparison to healthy individuals who took only one single dose of 100 mg ASA. Of the patients with CAD 63% had a COLL/EPI-CT within normal range suggesting a low or no response to ASA. Also only 50% of the patients undergoing PTCA reached the expected COLL/EPI-CT>300 s after an additive single dose of 500 mg ASA intravenously. Neither heparin, phenprocoumon, sex nor different blood sampling methods seem to influence the measurements relevantly.

CONCLUSIONS

This pilot study indicates that with the PFA-100(TM) test device a simple and quick measurement of an in vitro bleeding time is possible. It is able to detect an increase in the bleeding time after a single dose of ASA 100 mg in healthy subjects, reflecting a sensitive detection of ASA induced changes in platelet inhibition respective activation. Differences in the individual response to ASA could be observed in healthy subjects, patients with stable CAD and patients undergoing PTCA. Further studies should validate the PFA-100(TM) with standard methods to determine ASA response in patients with cardiovascular disease and investigate implications for treatment and outcome in this patient group.

Antiplatelet and anticoagulant therapy in elective percutaneous coronary intervention

Thrombosis plays a major role in acute vessel closure both after coronary balloon angioplasty and after stenting. This review will address the role of antiplatelet and anticoagulant therapy in preventing early thrombotic complications after percutaneous coronary intervention. The focus will be on agents that are routinely available and commonly used.