Evaluation of the coagulation and fibrinolytic systems in men with intermittent claudication

Anti-platelet and anti-coagulant therapy in peripheral arterial disease prior to surgical intervention

OBJECTIVE

Peripheral artery disease is a major clinical co-morbidity that can significantly affect quality of life, especially in the presence of diabetes mellitus and older age. The focus of this literature review is on medical management, through anti-platelet and anti-coagulation, of peripheral artery disease prior to undergoing surgical or endovascular management.

METHOD

Extensive electronic literature search performed in four major databases (PubMed, SCOPUD, Embase and Ovid) to identify the published randomized and non-randomized studies that compared and discussed the management of peripheral artery disease with different anti-thrombotic agents.

RESULTS

A total of 17 studies were identified to meet the inclusion criteria of this review. Among them, 4 were systematic review and meta-analyses, 1 was observational study and 12 were randomized controlled trials. The reported outcomes in each study are summarized and reported separately within this review.

CONCLUSION

Peripheral artery disease is a complex and multifactorial clinical condition. The use of dual anti-platelets, such as aspirin and clopidogrel, are the key in preventing major cardiovascular events as well as stroke and death. Utilization of anti-coagulation such as direct oral anti-coagulants' as additional parameters for the prevention of disease progression, is paramount. Eventually, the choice of either dual-antiplatelet therapy or combined anti-coagulation with anti-platelets should be carefully considered, particularly following the most recent published debatable studies.

Antithrombotic therapy in peripheral artery disease

Antiplatelet agents are recommended for the reduction of major adverse cardiovascular events among all patients with symptomatic peripheral artery disease. However, the optimal antiplatelet regimen and duration of therapy in peripheral artery disease (PAD) remains unclear, largely due to limited and conflicting data in this patient population. This article reviews current data on antithrombotic therapy in PAD and discusses the implications of this data for current practice and future research.

Criticial limb ischemia: epidemiology

Critical limb ischemia is found in 12% of the U.S. adult population. Its clinical presentation varies from no symptoms to intermittent claudication, atypical leg pain, rest pain, ischemic ulcers, or gangrene. Those with critical limb ischemia have a high incidence of cardiovascular comorbidities that reflect a significant systemic atherosclerotic burden; they have increased functional impairment and increased rates of functional decline compared with persons without critical limb ischemia. Interventions for critical limb ischemia and the impact of major amputation have a significant social and economic impact. At 1 year, 25% of patients will be dead, 30% will have undergone amputation, and only 45% will remain alive with both limbs. At 5 years, more than 60% of patients with critical limb ischemia will be dead.

Antithrombotic treatment for peripheral arterial disease

CONTEXT

Patients with peripheral arterial disease (PAD) bear a substantial risk for vascular events in the coronary, cerebral and peripheral circulations. In addition, this disorder is associated with a systemic milieu characterised by ongoing platelet activation and heightened thrombogenesis.

OBJECTIVE

To determine the optimal antithrombotic prophylaxis for patients with PAD.

DATA SOURCES

Using terms related to PAD and antithrombotic agents, we searched the following databases for relevant articles: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, the National Institutes of Health Clinical Trials Database, Web of Science, and the International Pharmaceutical Abstracts Database (search dates: 1 January 1990 to 1 January 2007). Additional articles were identified from cardiovascular and vascular surgery conference proceedings, bibliographies of review articles, and personal files.

STUDY SELECTION

We focused on randomised trials, systematic reviews and consensus guidelines of antithrombotic therapies for PAD.

DATA EXTRACTION

Detailed study information was abstracted by each author working independently.

RESULTS

Multiple studies show that patients with PAD manifest platelet hyperaggregability, increased levels of soluble platelet activation markers, enhanced thrombin generation and altered fibrinolytic potential. Many of these markers predict subsequent cardiovascular events. Available randomised trials and meta-analyses show that most available antithrombotic agents prevent major cardiovascular events and death in patients with PAD, including aspirin, aspirin/dipyridamole, clopidogrel, ticlopidine, picotamide and oral anticoagulants.

CONCLUSIONS

Although the most favourable risk-benefit profile, cost-effectiveness and overall evidence base supports aspirin in this setting, we provide scenarios in which alternatives to aspirin should be considered.

Relationship between soluble thrombomodulin in patients with intermittent claudication and critical ischemia

INTRODUCTION

Thrombomodulin (TM) has been described as a marker of endothelial injury in atherosclerosis. The role of TM as a predictor of PAD severity is to be proven. The goal of the present study is to compare the level of plasmatic (TMp) in patients with intermittent claudication with patients with critical ischemia in the lower limbs.

MATERIALS AND METHODS

TMp was measured using ELISA in the plasma of 41 patients with intermittent claudication degree 1 and in 40 patients presenting critical ischemia in the lower limbs degrees 2 and 3, according to TASC. The hypotheses of normality and homogeneity of the variance had been proven via Shapiro-Wilk and Levene tests, respectively. The comparison of the TMp between the groups was done using the t-Student test.

RESULTS

No statistically significant difference was observed. The average levels of TMp for intermittent claudication were 5.2 ng/ml (0.78-13.61 ng/ml) and TMp for critical ischemia in the lower limbs were 6.34 (0.82-18.22 ng/ml) where p=0.265.

CONCLUSION

TMp does not seem to be an appropriate marker for PAD severity.

Peripheral arterial disease

Lower extremity peripheral arterial disease (PAD) most frequently presents with pain during ambulation, which is known as "intermittent claudication". Some relief of symptoms is possible with exercise, pharmacotherapy, and cessation of smoking. The risk of limb-loss is overshadowed by the risk of mortality from coexistent coronary artery and cerebrovascular atherosclerosis. Primary therapy should be directed at treating the generalised atherosclerotic process, managing lipids, blood sugar, and blood pressure. By contrast, the risk of limb-loss becomes substantial when there is pain at rest, ischaemic ulceration, or gangrene. Interventions such as balloon angioplasty, stenting, and surgical revascularisation should be considered in these patients with so-called "critical limb ischaemia". The choice of the intervention is dependent on the anatomy of the stenotic or occlusive lesion; percutaneous interventions are appropriate when the lesion is focal and short but longer lesions must be treated with surgical revascularisation to achieve acceptable long-term outcome.

Hemostasis and fibrinolysis in patients with intermittent claudication: effects of prostaglandin E1

There is evidence that the coagulation system is activated in patients with peripheral arterial occlusive disease (PAOD). The beneficial effects of the vasoactive drug prostaglandin E1 (PGE1) may rely in part on the modulation of the coagulation system. The study was designed to evaluate the effects of PGE1 on hemostatic and fibrinolytic variables in patients with intermittent claudication. Therefore molecular markers of thrombin (prothrombin fragment 1+2, PTF 1+2; thrombin-antithrombin III complexes, TAT) and fibrin formation (fibrinopeptide A, FPA) and markers of the fibrinolytic activity (fibrin degradation products, D-dimers) were determined before and immediately after the first PGE1 dose (60 microg in 100 ml NaCl over 2 h i.v.) as well as after 4 weeks of daily infusion therapy in 12 PAOD patients and in eight control patients before and after a single placebo infusion. Plasma levels of PTF1+2, TAT, FPA and D-dimers tended to decrease after the initial dose of PGE1. Infusion therapy with PGE1 for 4 weeks led to a decrease of all hemostatic and fibrinolytic parameters with most pronounced changes for PFT1+2, D-dimers and plasminogen activator inhibitor-1 decreasing by 11% (P<0.05), 20% (P<0.05), and 7% (P<0.05), respectively. These variables remained unchanged in controls with placebo infusion. In summary, infusion therapy with PGE1 in patients with PAOD reduces thrombin formation and results in a decrease of fibrin degradation. PGE1 may thus reduce fibrin deposition involved in the pathogenesis of atherosclerosis.

Progressive intermittent claudication is associated with impaired fibrinolysis

PURPOSE

Acute complications of atherosclerosis such as stroke and myocardial infarction are caused by thrombosis and may be associated with impaired fibrinolytic activity. The current study was performed to determine whether peripheral arterial disease (PAD) and its progression are also associated with impaired fibrinolysis, by measurement of tissue plasminogen activator (tPA, the activator of fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1).

METHODS

The study group consisted of 80 men with a mean age of 69 years. This included 18 patients with mild intermittent claudication (MC, pain-free walking distance > or = 200 meters) and 51 patients with severe claudication (SC, walking distance <200 meters). Eleven age- and sex-matched patients without PAD served as controls. All patients had measurements of serum tPA antigen using an enzyme-linked immunoadsorbent assay. Serum levels of tPA and PAI-1 activity were assayed with an amidolytic method. Mean +/- SEM levels of the enzyme levels in patients with progressively more severe PAD were compared with normal controls.

RESULTS

Serum PAI-1 activity levels were significantly elevated in both PAD groups compared with normal controls (p < 0.02). There were no significant differences in the PAI-1 activity levels in groups with worsening degrees of PAD. There was a significant decrease in tPA activity levels in patients with SC (p = 0.01) relative to those with MC and the normal subjects. There was also a significant increase in tPA antigen level in the patients with SC compared with those with MC and the control subjects, as well as a significant inverse correlation between tPA antigen levels and pain-free walking time in patients with claudication (p = 0.001).

CONCLUSIONS

All patients with PAD in this study had significant reductions in endogenous fibrinolytic activity. Patients with SC had more impaired fibrinolytic activity than those with MC and the control subjects, suggesting that the progression to more severe levels of PAD may be associated with worsening endogenous fibrinolysis.