A Systematic Review and Meta-Analysis on the Impact of High On-Treatment Platelet Reactivity on Clinical Outcomes for Patients Taking ADP Receptor Inhibitors Following Lower Limb Arterial Endovascular Intervention

OBJECTIVE

Adenosine diphosphate (ADP) receptor inhibitors such as clopidogrel are known to be less effective at reducing platelet function for some patients because of a phenomenon called high on-treatment platelet reactivity (HTPR). However, the clinical effect of this for patients undergoing endovascular intervention for peripheral arterial disease is unclear. The aim of this study was to assess the impact of ADP receptor inhibitor HTPR on clinical outcomes following lower limb arterial endovascular intervention for peripheral arterial disease.

METHODS

A systematic review and meta-analysis was performed. Primary outcomes included all cause mortality and major bleeding. Secondary outcomes were major adverse cardiovascular events, major adverse limb events, restenosis, and target lesion revascularisation. Outcome quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool.

RESULTS

There were 10 eligible studies including 1 444 patients included in the meta-analysis. The most commonly tested ADP receptor inhibitor was clopidogrel (seven studies). The pooled rate of ADP receptor inhibitor HTPR was 29% (95% CI 27 - 32). The meta-analysis showed that ADP receptor inhibitor HTPR was associated with a greater risk of major adverse limb events (OR 6.25, 95% CI 2.09 - 18.68, p = .001) and a trend towards a higher all cause mortality (OR 1.71, 95% CI 0.99 - 2.94, p = .050) and more major adverse cardiovascular events (OR 4.23, 95% CI 0.46 - 38.92, p = .20) after endovascular intervention. Overall strength of evidence was very low for all outcomes.

CONCLUSION

ADP receptor inhibitor HTPR was associated with worse clinical outcomes after lower limb endovascular intervention for peripheral arterial disease. Prospective studies are required to determine the impact of modifying the antithrombotic regimen on clinical outcomes.

Altered Fibrinolysis during and after Surgery

Major surgery induces hemostatic changes related to surgical stress, tissue destruction, and inflammatory reactions. These changes involve a shift of volume from extravascular space to intravascular and interstitial spaces, a "physiologic" hemodilution of coagulation proteins, and an increase of plasmatic fibrinogen concentration and platelets. Increases in fibrinogen and platelets together with a simultaneous dilution of pro- and anticoagulant factors and development of a hypofibrinolytic status result in a postoperative hypercoagulable state. This profile is accentuated in more extensive surgery, but the balance can shift toward hemorrhagic tendency in specific types of surgeries, for example, in prolonged cardiopulmonary bypass or in patients with comorbidities, especially liver diseases, sepsis, and hematological disorders. Also, acquired coagulopathy can develop in patients with trauma, during obstetric complications, and during major surgery as a result of excessive blood loss and subsequent consumption of coagulation factors as well as hemodilution. In addition, an increasing number of patients receive anticoagulants and antiplatelet drugs preoperatively that might influence the response to surgical hemostasis. This review focuses on those situations that may change normal hemostasis and coagulation during surgery, producing both hyperfibrinolysis and hypofibrinolysis, such as overcorrection with coagulation factors, bleeding and hyperfibrinolysis that may occur with extracorporeal circulation and high aortic-portal-vena cava clamps, and hyperfibrinolysis related to severe maintained hemodynamic disturbances. We also evaluate the role of tranexamic acid for prophylaxis and treatment in different surgical settings, and finally the value of point-of-care testing in the operating room is commented with regard to investigation of fibrinolysis.

Viscoelastic Hemostatic Assays and Platelet Function Testing in Patients with Atherosclerotic Vascular Diseases

Platelets play crucial role in acute vascular atherosclerotic diseases, including myocardial infarction and stroke. Additionally, platelet aggregation is a key target of antiplatelet agents, forming the keystone of pharmacotherapy of various atherosclerotic cardiovascular diseases. Thromboelastography and thromboelastometry, representing currently available viscoelastic hemostatic assays (VHA), are designed as whole blood, real-time analyzers of clot formation and clot resolution. These assays could, in theory, overcome some limitations of currently available platelet function testing assays. This article reviews the current experience with the use of VHA for platelet function testing and for monitoring of the response to antiplatelet therapy.

Tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in patients with symptomatic lower extremity artery disease

BACKGROUND

Lower extremity artery disease (LEAD) involves progressive arterial narrowing manifested by intermittent claudication (IC). LEAD entails endothelial dysfunction and fibrinolytic disorders. In the current study, we analyze the selected parameters of the fibrinolytic system in the blood of patients with symptomatic LEAD depending on clinical parameters.

METHODS

The test group was comprised of 80 patients with diagnosis of LEAD based on Ankle-Brachial Index (ABI) test (27 female/53 male) with an average age of 63.5±9 years. The control group included 30 healthy, non-smoking volunteers (10 female/20 male), with the median age of 56±6 years. The research material - venous blood - was sampled to determine the concentrations of tissue-type plasminogen activator (t-PA Ag), plasminogen activator inhibitor type 1 (PAI-1 Ag), D-dimer, fibrinogen, and platelet count (PLT).

RESULTS

We found elevated concentrations of t-PA Ag, PAI-1 Ag, D-dimer, and fibrinogen in the plasma of subjects with symptomatic LEAD. Various stages of the Fontaine classification demonstrated a gradual, statistically significant increase in the concentrations of fibrinogen and PLT count as the disease progressed. More so, in the subgroup of LEAD patients aged ≥65 years, we observed significantly higher levels of D-dimer than in the group of younger subjects. In addition to that, the LEAD group demonstrated negative correlations of IC distance, fibrinogen concentrations, and PLT count, negative correlations of ABI at rest and concentrations of D-dimer and PLT count, as well as positive correlations between age and D-dimer levels.

CONCLUSIONS

High t-PA Ag concentrations in LEAD patients suggest damage to the endothelium which comprises the main source of this factor. With high PAI-1 Ag levels, inactive fibrinolytic t-PA-PAI-1 complexes are formed. Increasing fibrinogen concentrations at the subsequent stages in accordance with the Fontaine classification, indicate increasing inflammation. Moreover, heightened values of D-dimer reflect an increased secondary fibrinolysis activation as patients get older and impaired extremity vascularization, manifested by the decreasing ABI, progresses.

Perioperative cardiovascular complications rate and activity of coagulation and fibrinolysis among patients undergoing vascular surgery for peripheral artery disease and abdominal aortic aneurysm

OBJECTIVES

To compare preoperative coagulation and fibrinolysis activity and incidence of perioperative complications between patients undergoing vascular procedures for peripheral artery disease and abdominal aortic aneurysm.

METHODS

This is a substudy of a prospective observational cohort study (VISION; NCT00512109) in which we recruited patients aged ≥45 years, undergoing surgery for peripheral artery disease and abdominal aortic aneurysm. Blood samples were obtained 24 h preoperatively to measure platelet count, concentrations of coagulation coagulation (fibrinogen, factor VIII, von Willebrand factor:Ristocetin cofactor, antithrombin III), fibrinolysis (dimer D, plasmin-antiplasmin complexes, tissue plasminogen activator) markers and level of soluble CD40 ligand. Incidence of myocardial infarction, stroke, and death (composite endpoint) was assessed in 30-day follow-up.

RESULTS

The study group included 131 patients at the mean age of 68.3 years among whom reason for surgery was peripheral artery disease in 77 patients (58.8%) and abdominal aortic aneurysm in 54 patients (41.2%). Peripheral artery disease group was characterized by higher platelet count (250.5 versus 209.5 (×10³/µl), p = 0.001), concentrations of fibrinogen (5.4 versus 4.1 (g/l), p < 0.001), factor VIII (176.9 versus 141.9 (%), p < 0.001), von Willebrand factor:Ristocetin cofactor (188.9 versus 152.3 (%), p = 0.009), and soluble CD40 ligand (9016.0 versus 7936.6 (pg/ml), p = 0.005). The dimer D level was higher (808.0 versus 2590.5 (ng/ml), p < 0.001) in the abdominal aortic aneurysm group. Incidence of major cardiovascular events (death, myocardial infarction, stroke) within 30 days from surgery did not differ between the groups (39.0% versus 29.6%, p = 0.27).

CONCLUSIONS

The study suggests higher activation of coagulation and relatively lower fibrinolytic activity in peripheral artery disease group compared to patients undergoing surgery for abdominal aortic aneurysm without a significant difference in cardiovascular outcomes.

Altered coagulation profile in peripheral artery disease patients

OBJECTIVE

Peripheral artery disease patients have been shown to be more susceptible to thrombotic events compared to non-peripheral artery disease patients. Therefore, the aim of this study was to investigate the coagulation profile in peripheral artery disease patients with chronic limb threatening ischemia, moderate peripheral artery disease patients with claudication, and non-peripheral artery disease controls.

METHODS

Chronic limb threatening ischemia patients were matched to peripheral artery disease patients with claudication and non-peripheral artery disease controls in a 1:1:1 ratio. Each patient had their cytokines, markers of thrombin generation, coagulation factors, natural anti-coagulants, fibrinolysis, and endothelial injury markers assessed.

RESULTS

Markers of thrombin activation, thrombin Fragments F1 + 2 (Frag 1 + 2), and thrombin-anti-thrombin complex were found to be significantly elevated in all peripheral artery disease and chronic limb threatening ischemia patients relative to non-peripheral artery disease controls. Similarly, relative to non-peripheral artery disease controls, inflammatory markers including C-reactive protein, soluble platelet factor 4, and neutrophil gelatinase-associated lipocalin were also found to be significantly upregulated in chronic limb threatening ischemia patients, but not in peripheral artery disease patients with claudication. Furthermore, our data demonstrated significant increases in markers of endothelial injury in chronic limb threatening ischemia patients relative to non-peripheral artery disease controls. Finally, decreases in natural anti-coagulants (protein C and protein S) and coagulation factors FIX, FXI, and FXII were also observed in chronic limb threatening ischemia patients when compared with non-peripheral artery disease controls.

CONCLUSIONS

Our data suggest that in relation to non-peripheral artery disease controls, chronic limb threatening ischemia patients are more hypercoagulable. However, peripheral artery disease patients with claudication appear to have similar levels of circulating procoagulant markers as non-peripheral artery disease patients. This may explain the increased risk of thrombotic events observed in chronic limb threatening ischemia patients.

A Review of Antithrombotic Treatment in Critical Limb Ischemia After Endovascular Intervention

Endovascular intervention is often used to treat critical limb ischemia (CLI). Post-intervention treatment with antiplatelet and/or anticoagulant therapy has reduced morbidity and mortality due to cardiovascular complications. The purpose of this review is to shed light on the various pharmacologic treatment protocols for treating CLI following endovascular procedures. We reviewed the literature comparing outcomes after antithrombotic treatment for patients with CLI. We characterized antithrombotic therapies into three categories: (1) mono-antiplatelet therapy (MAPT) vs. dual antiplatelet therapy (DAPT), (2) MAPT vs. antiplatelet (AP) + anticoagulant (AC) therapy, and (3) AC vs. AP + AC therapy. Relevant results and statistics were extracted to determine differences in the rates of the following outcomes: (1) re-stenosis, (2) occlusion, (3) target limb revascularization (TLR), (4) major amputation, (5) major adverse cardiac events, (6) all-cause death, and (7) bleeding. Studies suggest that DAPT reduces post-surgical restenosis, TLR, and amputation for diabetic patients, without increasing major bleeding incidences, compared to MAPT. Also, AP + AC therapy provides overall superior efficacy, with no difference in bleeding incidences, compared to antiplatelet alone. Additionally, the effects were significant for restenosis, limb salvage, survival rates, and cumulative rate of above ankle amputation or death. These results suggest that treatment with DAPT and AP + AC might provide better outcomes than MAPT following the endovascular intervention for CLI, and that the ideal treatment may be related to the condition of the individual patient. However, the studies were few and heterogenous with small patient populations. Therefore, further large controlled studies are warranted to confirm these outcomes.

High plateletcrit is associated with early loss of patency after open and endovascular interventions for chronic limb ischemia

OBJECTIVE

Plateletcrit (PCT) reflects the total platelet mass in blood and can be calculated from a complete blood count. We examined the effect of PCT on outcomes of endovascular and open interventions for chronic limb ischemia.

METHODS

Patients who underwent revascularization for chronic limb ischemia (Rutherford categories 3-6) between June 2001 and December 2014 were retrospectively identified. PCT on admission was recorded. Patients and limbs were divided into tertiles of low (0.046-0.211), medium (0.212-0.271), and high (0.272-0.842) PCT. Patency, limb salvage, major adverse limb events, major adverse cardiac events, and survival rates were calculated using Kaplan-Meier analysis and compared with log-rank test. Cox regression analysis was used for multivariate analysis.

RESULTS

A total of 1431 limbs (1210 patients) were identified and divided into low PCT (477 limbs in 407 patients), medium PCT (477 limbs in 407 patients), and high PCT (477 limbs in 396 patients) groups. The patients in the high tertile were 2 years older that the patients in the other two tertiles (P = .009). Five-year primary patency was 65% ± 3% in the low-PCT group compared with 55% ± 3% and 51% ± 3% in the medium and high PCT groups, respectively (P = .004). Five-year secondary patency was 81% ± 2% in the low PCT group compared with 82% ± 2% and 72% ± 3% in the medium and high PCT groups, respectively (P = .02). Five-year limb salvage rate was 86% ± 2% in the low PCT group compared with 79% ± 3% and 74% ± 3% in the medium PCT and high PCT groups, respectively (P = .004). Multivariate regression analysis showed that low PCT was independently associated with primary patency after endovascular interventions (hazard ratio, 0.67 [0.47-0.95]; P = .02) but not after open interventions (hazard ratio, 0.72 [0.43-1.21]; P = .21).

CONCLUSIONS

High PCT is associated with poor patency and limb salvage rates after interventions for lower extremity chronic limb ischemia. Multivariate regression analysis confirmed association of low PCT with improved primary patency after endovascular interventions but not after open interventions. High PCT may be a marker of increased platelet reactivity and could be used to identify patients at high risk for early thrombosis and failure after interventions.

Study of the Association of V640L (rs6133) Polymorphism in the Platelet P-selectin Gene with Acetylsalicylic Acid Resistance in Patients after Coronary Bypass Surgery

Aim.To study the association of V640L (rs6133) polymorphism in the P-selectin gene with acetylsalicylic acid (ASA) resistance in patients with coronary heart disease after coronary bypass surgery (CABG).Material and methods.The study included 104 patients aged 36-78 years (mean age 61.6±6.9 years) with stable angina pectoris: 61 (58.7%) patients had functional class II (according to Canadian Cardiovascular Society), 41 (39.4%) – class III and 2 (1.9%) – class IV. Atherosclerotic lesions of the coronary arteries were confirmed by coronary angiography. The antiplatelet therapy was stopped for at least 5 days before CABG. In the postoperative period, from the first day, all patients received 100 mg of ASA in enteric form, 61 patients received alone ASA therapy, 43 patients – combined antiplatelet therapy: ASA+clopidogrel (75 mg/day). The aggregation study was performed with an optical aggregometer, using 5 μM adenosinediphosphate (ADP) and 1 mM arachidonic acid inductors before CABG, on 1-3 day and on 8-10 day after surgical treatment. DNA samples were examined for the V640L (rs6133) polymorphism in the P-selectin gene by real-time polymerase chain reaction (PCR) using the allele-specific primers.

Results. The frequency of the homozygous GG genotype of the rs6133 polymorphism was 84.6%; heterozygous GT genotype – 15.4%. The amplitude of aggregation with ADP before CABG, on 1-3 day and on 8-10 day after CABG for carriers of homozygotes of allele G vs carriers of the allele T were: 47.9±19.3%, 44.5±17.8%, 30.1±13.2% vs 47.9±17.1%, 46.3±16.5%, 39.6±22.0%, respectively (p=0.497, 0.441 and 0.687, respectively). The amplitude of aggregation with arachidonic acid before CABG, on 1-3 day and on 8-10 day after CABG for carriers of homozygotesof allele G vs carriers of the allele T, were: 47.9±23.2%, 24.5±21.7%, 12.3±16.3% vs 54.3±17.8%, 29.7±23.7%,  11±10.9%, respectively (p=0.416, 0.825 and 0.872, respectively). In the first 10 days of the postoperative period, 6 thrombotic events (5.7%) were observed in the study group: 2 strokes and 4 perioperative myocardial infarctions. Five events occurred in the group of patients with the GG genotype, 1 event in the group of patients with the GT genotype.Conclusion. V640L (rs6133) polymorphism in the P-selectin gene is not associated with ASA resistance in patients with coronary artery disease after CABG. The T allele of the rs6133 polymorphism is not associated with increased platelet aggregation activity after CABG and does not increase the risk of adverse events in the first 10 days after CABG.