Relationship between antiphospholipid antibodies and progression of lower extremity arterial occlusive disease after lower extremity bypass operations

Anticoagulation in Patients with Premature Peripheral Artery Disease Undergoing Lower Extremity Revascularization

BACKGROUND

Premature peripheral artery disease (PAD), defined by lower extremity revascularization (LER) at age ≤ 50 years, is associated with poor major adverse limb events. The early onset of disease is thought to be influenced by genetic factors that regulate homeostasis of the vascular wall and coagulation. The aim of this study is to investigate the effect of anticoagulation as an adjunct to antiplatelet therapy on the outcomes of LER in patients with premature PAD.

METHODS

There were 8,804 patients with premature PAD on preoperative and postoperative antiplatelet therapy only and 1,236 patients on preoperative and postoperative anticoagulation plus antiplatelet therapy in the Vascular Quality Initiative peripheral vascular intervention, infrainguinal, and suprainguinal files. Propensity score matching (2:1) was performed between patients with premature PAD who were on antiplatelet therapy and those on anticoagulation plus antiplatelet therapy. Perioperative and 1-year outcomes were analyzed including reintervention, major amputation, and mortality.

RESULTS

Patients on anticoagulation were more likely to have coronary artery disease (48.7% vs. 41.2%, P < 0.001), congestive heart failure (20.2% vs. 13.1%, P < 0.001), and have undergone prior LER (73.9% vs. 49.2%, P < 0.001) compared to patients on antiplatelet therapy only. They were also less likely to be independently ambulatory (74.2% vs. 81.8%, P < 0.001) and be on a statin medication (66.8% vs. 74.3%, P < 0.001) compared to patients on antiplatelet therapy only. Patients on anticoagulation were also less likely to be treated for claudication (38.1% vs. 48.6%, P < 0.001), and less likely to be treated with an endovascular procedure (64.8% vs. 73.8%, P < 0.001). After matching for baseline characteristics, there were 1,256 patients on antiplatelet therapy only and 628 patients on anticoagulation. Patients on anticoagulation were more likely to require a return to the operating room (3.7% vs. 1.6%, P < 0.001) and had higher perioperative mortality (1.1% vs. 0.3%, P = 0.032), but major amputation was not significantly different (1.8% vs. 1.6%, P = 0.798) compared to patients on antiplatelet therapy alone. At 1 year, amputation-free survival was higher in patients on antiplatelets only compared to patients on anticoagulation and antiplatelet medications (87.5% vs. 80.9%, log-rank P = 0.001).

CONCLUSIONS

Anticoagulation in addition to antiplatelet therapy in patients with premature PAD undergoing LER is associated with increased reintervention and mortality at 1 year.

Antiphospholipid antibodies and lower extremity peripheral artery disease: A systematic review and meta-analysis

AIM

To evaluate the clinical relevance of antiphospholipid antibodies (aPL) in patients with lower extremity peripheral artery disease (PAD).

DATA SOURCES

EMBASE and MEDLINE databases were searched from inception to March 2020 for clinical studies reporting on the association between of aPL [IgG/IgM anticardiolipin (aCL) and lupus anticoagulant (LA)] and PAD.

METHODS

We determined the pooled prevalence (PP) of patients positive for aPL in PAD or the PP of PAD in patients positive for aPL; we employed Peto's odds ratio with random effect for the meta-analysis.

RESULTS

Twenty-one studies comprising 6,057 patients were evaluated: in patients with PAD, the PP of IgG aCL was 12% vs 4.1% in those without, IgM aCL was 13.2% vs 2.1%, and LA 13.3% vs 3.3%, respectively. The PP of patients with LA was greater in critical limb ischemia than in the control group (19.3% vs 4.2%). Also, the PP of patients with LA was greater in the failed than in the successful revascularisation group (35.8% vs 15.8%). The PP of post-procedural revascularisation failures was similar in the groups given or not given oral anticoagulation (59.2% vs 61.9%).

CONCLUSION

All the aPL related to PAD regardless of diagnostic definition used, whereas LA related also to critical limb ischaemia and failed revascularisation. Data expressed as percentage of participants positive for aPL limit the interpretation of these relationships.

Antiphospholipid antibodies in end-stage renal disease: A systematic review and meta-analysis

INTRODUCTION

The relationship between autoimmune hemolytic anemia and antiphospholipid antibodies (aPL) and/or antiphospholipid syndrome has never been systematically addressed.

METHODS

Systematic review of EMBASE and PubMed databases performed according to PRISMA guidelines from inception to March 2020; meta-analysis performed by Peto's odds ratio for rare events.

FINDINGS

Forty-five studies with different outcomes met the inclusion/exclusion criteria. The pooled prevalence (PP) of IgG anticardiolipin antibodies (aCL) positivity was greater in end-stage renal disease (ESRD) than controls (20.2% vs. 2.6%, P = 0.001, I²  >80%; I² = heterogeneity), particularly in hemodialysis patients (18.3% vs. 8%, I² = 0%). The PP of lupus anticoagulant was greater in ESRD than controls (8.7% vs. 0.2%, P < 0.0001, I² = 0%). The standardized mean difference of IgG aCL favored ESRD rather than controls (P < 0.0001, I² =97%). The PP of fistula occlusion was greater in IgG aCL-positive patients than negative patients (39% vs. 27%, I² =97%); the PP of IgG aCL positivity was greater in patients with fistula occlusion than without fistula occlusion (26.9% vs. 23.2%, P = 0.01, I² =72%); the same applied to the PP of lupus anticoagulant positivity (23% vs. 0.3%, P < 0.0001, I² = 0%). The standardized mean difference of IgG aCL favored fistula occlusion (P = 0.004, I² = 91%).

DISCUSSION

Lupus anticoagulant relates to ESRD regardless of management whereas IgG aCL relates specifically to ESRD on hemodialysis, but only lupus anticoagulant associates with fistula occlusion. The expression of aPL as patients positive for aPL rather than as titers precludes further assumptions on the relationship.

Anticardiolipin Antibodies as a Risk Factor of Atherosclerosis in Intermittent Claudication

Anticardiolipin antibodies have been associated as a risk factor of atherosclerosis. The aim of this study was to evaluate the association between anticardiolipin antibodies and intermittent claudication. Forty consecutive patients (33 men, 7 women; age range: 45-84 years, mean 65.5) who were seen in the angiology and vascular surgery department with intermittent claudication were evaluated. Exclusion criteria included prior revascularization, angioplasty, or a history of thrombosis of a lower limb. Forty individuals (23 men, 17 women; age range: 58-82 years, mean 67.1) who attended a support group for senior citizens and who were apparently healthy formed the control group. Anticardiolipin antibodies were evaluated by means of enzyme-linked immunosorbent assay (ELISA) for quantitative measurement of immunoglobulin G (IgG) and IgM antibodies against cardiolipins in serum. IgG levels were considered normal when <7, borderline from 7 to 10, and elevated at >10 GPL units/mL; IgM levels were normal when <4, borderline from 4 to 7, and elevated at >7 MPL, as recommended by the test manufacturers. Statistical analysis used the relative risk test with a confidence interval of 95%. Twenty-three patients from the study group and 6 individuals from the control group were found to have elevated levels of anticardiolipin antibodies giving a relative risk of 3.833 (ranging from 1.749 to 8.4; p value <0.0001). In conclusion, patients who have elevated levels of anticardiolipin antibodies present a 3.8 times greater risk of developing intermittent claudication.

Autoantibodies to the Atheroma Component Beta2-Glycoprotein I and Risk of Symptomatic Peripheral Artery Disease

Peripheral artery disease (PAD) is mostly related to atherosclerosis. Autoimmunity and, in particular, antibodies to cardiolipin (aCL) and phospholipid cofactors such as beta2-glycoprotein I (beta2-gpI) might influence the development of atheroma. Beta2-glycoprotein I (beta2-gpI) has been found in atheroma. It has previously been shown that immunoglobulin A (IgA) anti-beta2-gpI antibodies are associated with a risk of cerebral ischemia and myocardial infarction. This case control study aimed to determine whether elevated levels of aCL/anti-beta2-gpI antibodies are associated with a risk of symptomatic PAD (sPAD). Cases comprised a nonselected population of patients with sPAD (intermittent claudication or critical ischemia). Patient recruitment was based on arteriography changes. Controls were selected from patients admitted to orthopedic wards as a result of fractures or muscle-ligamentous disorders. Age, sex, race, hypertension, smoking, diabetes mellitus, and hypercholesterolemia were evaluated as risk factors in both groups. IgG/IgM/IgA aCL and anti-beta2-gpI were detected by enzyme-linked immunoabsorbant assays (ELISA). To estimate the grade of association of antibodies with sPAD, odds ratios (OR) were calculated. Logistic regression was utilized for adjustment of confounding factors. Seventy-seven cases and 93 controls were studied. The mean age was 61.5 years for cases and 47.5 years for controls (p <0.001). Among the risk factors evaluated, the presence of hypertension showed the strongest association with sPAD (OR 12.1; 95%CI 5.8—30). The presence of IgA anti-beta2-gpI was independently associated with sPAD (OR 5.4; 95%CI 1.8—15.8; p = 0.01). IgA aCL was strongly associated with the outcome (nonadjusted OR 11.5 after Agresti correction). IgA aCL and IgA anti-beta2-gpI antibodies were not associated with any known risk factors for sPAD or with arteriography changes. The occurrence of these autoantibodies might represent one of the links between autoimmunity and atherosclerosis in patients with sPAD.

Epidemiology of peripheral artery disease

New data on the epidemiology of peripheral artery disease (PAD) are available, and they should be integrated with previous data. We provide an updated, integrated overview of the epidemiology of PAD, a focused literature review was conducted on the epidemiology of PAD. The PAD results were grouped into symptoms, diagnosis, prevalence, and incidence both in the United States and globally, risk factors, progression, coprevalence with other atherosclerotic disease, and association with incident cardiovascular morbidity and mortality. The most common symptom of PAD is intermittent claudication, but noninvasive measures, such as the ankle-brachial index, show that asymptomatic PAD is several times more common in the population than intermittent claudication. PAD prevalence and incidence are both sharply age-related, rising >10% among patients in their 60s and 70s. With aging of the global population, it seems likely that PAD will be increasingly common in the future. Prevalence seems to be higher among men than women for more severe or symptomatic disease. The major risk factors for PAD are similar to those for coronary and cerebrovascular disease, with some differences in the relative importance of factors. Smoking is a particularly strong risk factor for PAD, as is diabetes mellitus, and several newer risk markers have shown independent associations with PAD. PAD is strongly associated with concomitant coronary and cerebrovascular diseases. After adjustment for known cardiovascular disease risk factors, PAD is associated with an increased risk of incident coronary and cerebrovascular disease morbidity and mortality.

Circulating anti-β2-glycoprotein I antibodies of peripheral arterial disease patients trigger a genomic overexpression of Toll-like receptor 4 in endothelial cells

OBJECTIVE

Circulating anti-β2-glycoprotein I (ABGPI) antibodies are associated with peripheral arterial disease (PAD) and induce the expression of leukocyte adhesion molecules and proinflammatory cytokines by endothelial cells. Our aim is to study a transcriptional activation pathway of the innate immune system through the cellular signalling cascade triggered by receptors Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) of endothelial cells after the exposure of these cells to seropositive ABGPI human serum obtained from PAD patients.

METHODS

We obtained serum samples from PAD patients and controls without PAD. ABGPI serum titer was detected using indirect immunofluorescence. Our sample was stratified into three groups: group I (PAD and ABGPI titer ≥1:100; n = 15), group II (PAD and ABGPI titer <1:100; n = 15), and control participants (no PAD; n = 15). All serum samples were incubated with human aortic endothelial cell (HAEC) culture. Genomic expression of TLR2 and TLR4 receptors and their shared intracellular signalling molecules, myeloid differentiation primary response gene 88 (MyD88), and interleukin (IL)-1 receptor-associated kinase (1IRAK1), were measured after the exposure of HAECs to each serum.

RESULTS

HAEC genomic expression of TLR4 was higher after the exposure to group I serum than after the exposure to group II serum (log10×10-relative quantification [RQ]: 1.80 ± 0.42 vs 1.37 ± 0.39; P = .01) or control serum (log10×10-RQ: 1.80 ± 0.42 vs 1.09 ± 0.26; P < .01). TLR4 expression was higher in group II than in the control group (log10×10-RQ: 1.37 ± 0.39 vs 1.09 ± 0.26; P = .04). TLR4 expression correlated with MyD88 (r = 0.54; P < .01) and IRAK1 (r = 0.55; P < .01) expression. We recorded a positive correlation between MyD88 and IRAK1 genomic expression (r = 0.58; P < .01).

CONCLUSIONS

Our results suggest that serum from PAD patients with elevated ABGPI antibodies induces a genomic overexpression of TLR4 and its cellular signalling molecules in endothelial cells.

Hybrid treatment of lower limb critical ischemia in a patient with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory multisystemic disease, which affects primarily small-sized vessels, arterioles, venules, and capillaries in the cardiovascular system. Less often, medium-sized vessels are affected, and large-sized vessels are affected rarely. We report an unusual case of a 52-year-old female patient with SLE under treatment and multileveled arterial obstructive disease of the lower limb, who presented with critical limb ischemia. The patient was treated using a hybrid endovascular and open revascularization procedure, on the basis of the clinical picture of the patient, the angiographic findings, and the experience of our department. Our aim is not only to highlight the rarity of the clinical picture but also to make useful conclusions regarding the proper management for such unusual cases. Given the fact that there are no guidelines, we present the treatment strategy selected for our patient and discuss our results.

Antiphospholipid antibodies attenuate endothelial repair and promote neointima formation in mice

Background

Antiphospholipid syndrome patients have antiphospholipid antibodies (aPLs) that promote thrombosis, and they have increased cardiovascular disease risk. Although the basis for the thrombosis has been well delineated, it is not known why antiphospholipid syndrome patients also have an increased prevalence of nonthrombotic vascular occlusion. The aims of this work were to determine if aPLs directly promote medial hypertrophy or neointima formation in mice and to identify the underlying mechanisms.

Methods and Results

Medial hypertrophy and neointima formation invoked by carotid artery endothelial denudation were evaluated in mice administered normal human IgG or aPLs. While aPLs had no effect on medial hypertrophy, they caused exaggerated neointima development. This was related to an aPL‐induced impairment in reendothelialization post denudation, and scratch assays in cell culture revealed that there are direct effects of aPLs on endothelium that retard cell migration. Further experiments showed that aPL antagonism of endothelial migration and repair is mediated by antibody recognition of β2‐glycoprotein I, apolipoprotein E receptor 2, and a decline in bioavailable NO. Consistent with these mechanisms, the adverse impacts of aPLs on reendothelialization and neointima formation were fully prevented by the NO donor molsidomine.

Conclusions

APLs blunt endothelial repair, and there is related aPL‐induced exaggeration in neointima formation after endothelial injury in mice. The initiating process entails NO deficiency mediated by β2‐glycoprotein I recognition by aPLs and apolipoprotein E receptor 2. The modulation of endothelial apolipoprotein E receptor 2 function or NO bioavailability may represent new interventions to prevent the nonthrombotic vascular occlusion and resulting cardiovascular disorders that afflict antiphospholipid syndrome patients.

Atherosclerosis in primary antiphospholipid syndrome

Antiphospholipid syndrome (APS) is the most common cause of acquired thrombophilia, but experimental and clinical evidence accumulated over the years suggest that the clinical manifestations of APS go beyond those of a simple hypercoagulable state. Although still a controversial topic, the elevated risk of atherosclerosis in systemic lupus erythematosus seems little accounted for by the presence of antiphospholipid antibodies, whereas premature atherosclerosis has been addressed in few series of patients with primary APS. The available data in primary APS suggest that traditional risk factors for atherosclerosis are less involved in arterial disease, rather antiphospholipid antibodies appear as major players. Their effect on the coagulation system, the vessel wall and on the antioxidant/oxidant balance impairs vascular homeostasis, leading to premature arterial thickening.

[Thrombophilias and peripheral arterial occlusive disease]

Peripheral arterial occlusive disease is a frequent disease due to the classical vascular risk factors such as smoking, diabetes mellitus, dyslipidemia, and hypertension. Despite these risk factors, many thrombophilias (physiological inhibitors defects, Factor V Leiden and 20210A prothrombin gene variant, antiphospholipid antibodies, mild hyperhomocysteinemia 15-30micromol/l) can be evoked in some clinical forms of peripheral arterial occlusive disease. This paper provides a synthesis of the published data about this topic. Screening for these thrombophilias is justified in patients with venous thromboembolic disease, or signs of antiphospholipid syndrome and possibly in different situations such as premature atheroma of lower limbs, chronic ischaemia, evolutive disease despite adapted treatment and revascularisation failures without evident technical explanation. Except for the antiphospholipid syndrome, there is currently no consensus for systematic screening of thrombophilia and treatment in patients with peripheral arterial occlusive disease.

The prevalence of thrombophilia in patients with symptomatic peripheral vascular disease

Background

The aim of this prospective study was to establish the prevalence of thrombophilia and hyperhomocysteinaemia using a comprehensive screen in patients with peripheral vascular disease.

Methods

A total of 150 patients with peripheral vascular disease (with an ankle brachial pressure index of less than 0·8) underwent thrombophilia screening (protein C and protein S, antithrombin, lupus anticoagulant, activated protein C resistance and factor V Leiden and prothrombin mutations). Fasting homocysteine assays were also performed.

Results

A thrombophilia defect was found in 41 patients (27·3 per cent). The commonest was protein S deficiency, found in 17 patients (11·3 per cent). Others included factor V Leiden mutation, found in 10 (6·7 per cent) and protein C deficiency, found in six (4·0 per cent). Lupus anticoagulant and prothrombin mutation were both found in six (4·0 per cent). One patient had an antithrombin deficiency. Only the presence of critical ischaemia was associated with a positive thrombophilia screen on single variable analysis (P = 0·03). Hyperhomocysteinaemia was present in over a third of the study group (37·3 per cent): 45 defined as moderate and 11 as intermediate.

Conclusion

A quarter of patients with peripheral vascular disease had evidence of thrombophilia, and a third had hyperhomocysteinaemia.

Assessment of Hemostatic Risk Factors in Predicting Arterial Thrombotic Events

Arterial thrombosis results from endovascular injury and, to a lesser extent, alterations in hemostatic equilibrium. Although multiple hereditary and acquired hemostatic risk factors have been described in the pathophysiology of venous thrombosis, the degree and type of abnormalities that contribute to arterial thrombosis are less well understood. Endothelial cell injury with the elaboration of proinflammatory mediators stimulates the process of arterial thrombosis. Although this is most often the result of endovascular injury attributable to atherosclerotic disease, other disease states can elicit a similar response as well. Similarly, once thrombosis has been initiated, variations in the activity of coagulation proteins and endogenous anticoagulants, as well as the kinetics of platelet aggregation, may alter the effectiveness of thrombus formation. Epidemiological studies have identified several acquired or inherited states that may result in endothelial damage or altered hemostatic equilibrium, thereby predisposing patients to arterial thrombosis. These include hyperhomocysteinemia, elevated C-reactive protein, antiphospholipid antibodies, elevated fibrinogen, Factor VII, plasminogen activator inhibitor-1 (PAI-1), hereditary thrombophilias, and platelet hyper-reactivity. This review explores our present understanding of these risk factors in the development of arterial thrombotic events. At present, the literature supports a role for hyperhomocysteinemia, elevated C-reactive protein, and elevated fibrinogen as risk factors for arterial thrombosis. Similarly, the literature suggests that lupus anticoagulants and, to a lesser extent, elevated titers of cardiolipin IgG antibodies predispose to arterial vascular events. In certain subsets of patients, including those with concomitant cardiac risk factors, <55 years of age, and women, hereditary thrombophilias such as carriership of the factor V Leiden and the prothrombin G20210A mutations may confer a higher risk of arterial thrombosis. However, the data on Factor VII, PAI-1, and platelet receptor polymorphisms are contradictory or lacking.

Smoking and the patency of lower extremity bypass grafts: A meta-analysis

OBJECTIVE

Smoking is the major risk factor associated with the development and progression of peripheral arterial disease (PAD). To establish the best estimate of the effect of smoking, smoking cessation, and the dose-response relationship on the patency of lower extremity bypass grafts, we performed a systematic review.

METHODS

A search of medical articles and reviews relating to the influence of smoking on the patency of arterial reconstructive grafts in patients with PAD was made. Studies considered for inclusion were those that evaluated the influence of smoking on the primary, secondary, or cumulative patency rates of arterial reconstructive surgery in the lower extremities in patients with PAD. Primary data were used to calculate summary estimates with standard meta-analysis techniques.

RESULTS

The 29 eligible studies included 4 randomized clinical trials, 12 prospective studies, and 13 retrospective studies. The effect of smoking on graft patency in the randomized clinical trials and other prospective studies had a 3.09-fold (2.34 to 4.08; P < .00001) increase in graft failure. A comparison of patency rates among all studies that used autogenous or polyester grafts showed no difference. A clear dose-response relationship was present, with a decreased patency in heavy smokers compared with moderate smokers. Smoking cessation restores patency rates toward the never smokers group.

CONCLUSION

Continued smoking after lower limb bypass surgery results in a threefold increased risk of graft failure. Smoking cessation, even if instigated after the operation, restored graft patency towards the patency of never smokers. These results indicate that adequate smoking cessation strategies in patients eligible for lower limb bypass surgery are of utmost importance.

Thrombophilic risk factors in patients with severe carotid atherosclerosis

Carotid stenosis and atrial fibrillation are the strongest risk factors for ischemic stroke. Ongoing prevention efforts include the identification of novel factors that increase the risk for carotid atherosclerosis. The aim of this study was to determine the thrombophilic risk profile of patients with severe carotid stenosis by evaluating a number of genetic and metabolic risk factors [factor (F)II G20210A, factor V Leiden, MTHFR C677T polymorphisms, anticardiolipin antibodies (aCL), lipoprotein(a) (Lp(a)), and homocysteine (Hcy)]. The study population consisted of 615 patients [(410 M/205 F; median age 73 (26-94) years] with severe (> 70%) carotid stenosis, and 615 apparently healthy subjects [(410 M/205 F; age 73 (31-92) years]. On multivariate analysis, independent risk factors were elevated Hcy [odds ratio (OR) 7.6, 95% confidence interval (CI) 4.8, 11.8] and Lp(a) levels (OR 2.9, 95% CI 2.1, 3.9), the presence of aCL (OR 5.7, 95% CI 3.1, 10.4) and heterozygosity for FII G20210A polymorphism (OR 2.8, 95% CI 1.3, 5.9). In the subgroup of women, independent risk factors for severe carotid atherosclerosis were: high levels of Hcy and Lp(a) and the presence of aCL, whereas hyperhomocysteinemia, elevated Lp(a) levels, aCL, FII G20210A and MTHFR 677TT polymorphisms remained independent risk factors in the subgroup of men. The results of the present study demonstrate that the prevalence of the thrombophilic risk factors is increased in patients with severe carotid atherosclerosis.

Thrombophilic risk factors for symptomatic peripheral arterial disease

OBJECTIVE

Peripheral arterial disease (PAD) is a common manifestation of systemic atherosclerosis. Over the last years, several novel mediators relevant to the process of atherogenesis have been identified, but few and conflicting data are available on the possible association with PAD symptoms. The aim of this study was to determine an extended thrombophilic risk profile of patients with symptomatic PAD.

METHODS

Two hundred eighty patients with symptomatic PAD admitted to the Department of Vascular Surgery of the University of Florence were compared with 280 control subjects without PAD, matched for age and gender. The following metabolic and genetic risk factors were evaluated: lipoprotein(a), homocysteine, antiphospholipid antibodies, plasminogen activator inhibitor-1, factor V Leiden mutation, prothrombin variant, and 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism.

RESULTS

Multivariate logistic regression analysis, adjusted for traditional cardiovascular risk factors, showed a significant association between PAD symptoms and prothrombin variant, altered levels of homocysteine, lipoprotein(a), plasminogen activator inhibitor-1, and antiphospholipid antibodies. Moreover, the presence of high levels of lipoprotein(a) and another metabolic risk factor raised the likelihood of PAD symptoms (dyslipidemia and elevated lipoprotein[a]: odds ratio [OR], 29; 95% confidence interval [CI], 6.2 to 136.2; P <.0001; hyperhomocysteinemia and elevated lipoprotein[a]: OR, 37.7; 95% CI, 3.7 to 381.5; P <.0001). A significant correlation between the number of altered thrombophilic parameters and the Fontaine stage was observed ( R = 0.16; P = .006).

CONCLUSION

There is an independent association between altered levels of important thrombophilic risk factors and PAD symptoms. The clinical significance of this association needs to be tested in prospective population-based trials.

Current debates in antiphospholipid syndrome: the acquired antibody-mediated thrombophilia

Antiphospholipid (APL) syndrome is the most common form of acquired thrombophilia. It can cause significant morbidity and even mortality. The term "APL antibodies" represents a heterogeneous group of antibodies associated with this disorder. Currently no single assay can identify every APL antibody. Clinically relevant APL antibodies are mainly anticardiolipin antibodies (ACA) detected by solid phase enzyme-linked immunosorbent assay (ELISA) and lupus anticoagulants (LA) demonstrated by in vitro coagulation assay. However, there are some other antibodies associated with the APL syndrome (i.e., subgroup APL antibodies). ACAs, LAs, and subgroup APL antibodies represent intersecting, but non-identical, subsets of autoantibodies. Thus, those autoantibodies may coexist or may occur independently. Any organ system and any size of vessel can be affected during the clinical course of the disease. Therefore, the APL syndrome can manifest itself in a wide variety of clinical thrombotic features. Fetal loss and pregnancy morbidity represent a specific challenge. Despite tremendous advances in the understanding of the pathogenesis of APL syndrome during the past decade, the mainstay of management is still anticoagulation. However, there is no general agreement regarding the duration and intensity of anti-coagulant therapy. In this review, we focused on the current dilemmas and their present clarifications in the wide clinicopathologic spectrum of APL syndrome and APL antibody-related distinct pathologic conditions.

Prevalence and Risk of Thrombophilia Defects in Vascular Patients

This paper reviews the available data on the prevalence of thrombophilia defects in patients with peripheral vascular disease (PVD) and attempts to delineate the risk of failure of vascular intervention in these patients. The prevalence of thrombophilia in stable claudicants is 25% and increases to 40% in those requiring revascularisation, compared to only 11% in the control group. The overall prevalence of thrombophilia defects in patients with premature atherosclerosis appears to be between 15 and 30%. The prevalence in the typical cohort of patients with PVD appears to be similar. All these studies have recruited patients with symptoms significant enough to warrant intervention. The overall prevalence of thrombophilia calculated from these trials, therefore, may not be truly indicative of the general vascular population who may not even present primary or secondary healthcare. The risk of thrombotic occlusion following arterial revascularisation in patients with an identified thrombophilia defect appears to be almost three times that of patients with no evidence of a thrombophilia defect. The best management of these patients has not been determined and needs to be evaluated by prospective randomized trials.

Risk factors for autogenous infrainguinal bypass occlusion in patients with prosthetic inflow grafts

OBJECTIVE

In patients with prosthetic inflow (PI) grafts the proximal anastomosis of autogenous infrainguinal bypass (AIB) can be placed on the PI or on a distal native vessel in the groin. This study was performed to determine the effect of placement of an AIB proximal anastomotic site in a patient with ipsilateral PI.

METHODS

Patients undergoing AIB and PI between January 1990 and July 2002 were included in the study. They were classified into two groups on the basis of location of the proximal anastomosis. In group 1 the AIB proximal anastomosis was placed on the PI in the groin, whereas in group 2 the AIB proximal anastomosis was placed on a distal native groin artery. Patency, limb salvage, and patient survival in the two groups were calculated with the Kaplan-Meier method. The Cox proportional hazards model was used to determine independent risk factors affecting AIB patency.

RESULTS

Two hundred twenty-nine patients underwent AIB and PI. In group 1, 23 AIBs became thrombosed concurrent with 26 PI occlusions, and in group 2, 7 AIBs became thrombosed concurrent with 36 PI occlusions (P <.001). Five-year assisted primary patency, limb salvage, and patient survival in groups 1 and 2 were 50% and 75% (P <.001, log-rank test), 78% and 90% (P =.005, log-rank test), and 56% and 69% (P = NS, log-rank test), respectively. Factors independently associated with AIB occlusion are hypertension (hazard ratio [HR], 3.41; 95% confidence interval [CI], 1.65-7.05; P =.001), postoperative warfarin sodium therapy (HR, 1.86; 95% CI, 1.07-3.23; P =.03), continued smoking (HR, 1.72; 95% CI, 0.93-3.18; P =.08), AIB arising from PI (HR, 2.38; 95% CI, 1.35-4.18; P =.003), and PI occlusion (HR, 3.70; 95% CI, 2.15-6.36; P <.001).

CONCLUSION

A proximal AIB anastomosis located directly on the PI is an independent risk factor for decreased AIB patency of equal or greater importance than current smoking, hypertension, or PI occlusion. The proximal anastomosis of an AIB in a patient with an ipsilateral PI should be placed on a distal native artery.

Peripheral vascular disease in antiphospholipid syndrome

Atherosclerosis has been considered an inflammatory disease based on the finding that atherosclerotic lesion contains activated T lymphocytes reacting with oxidized low-density lipoproteins (oxLDL) and heat shock proteins (HSP); it also contains autoantigens like beta2GPI, a target of antibodies occurring in an immune-mediated thrombophilia called antiphospholipid syndrome (APS). Further support to this hypothesis comes from the cross-reactivity, which occurs between antiphospholipid antibodies (aPL) and antibodies to oxLDL. Animal experiments have shown that aPL are associated with atheroma. In addition, accelerated atherosclerosis has been detected in patients with a prototype systemic autoimmune disease, such as systemic lupus erythematosus (SLE). However, the association of APS or aPL with atherosclerosis is a matter of debate due to the small numbers of patients studied, and the fact that traditional risk factors for atherosclerosis coexist. The prevalence of APS ranges from 1.7% to 6%, and that of aPL reaches to 14% among patients with peripheral vascular disease defined on the basis of clinical outcomes. On the other hand, the prevalence of asymptomatic atherosclerosis, defined in terms of plaques in ultrasonography, reaches to 15% of patients with APS compared to 9% of SLE patients and 3% of normal controls. Among SLE patients with aPL, the prevalence of plaques ranges from 6% in premenopausal women to 31% in unselected patients. Less than 10% of APS patients express premature atherosclerosis in the absence of other risk factors. Which APS patient will develop atherosclerosis is unpredictable.

Laboratory evaluation of hypercoagulability with venous or arterial thrombosis

OBJECTIVE

To provide recommendations for hypercoagulation testing for patients with venous, arterial, or neurovascular thrombosis, as reflected in the medical literature and the consensus opinion of recognized experts in the field.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

The authors extensively examined the literature and current practices, and prepared a draft manuscript with preliminary recommendations. The draft manuscript was circulated to each of the expert participants (n = 30) in the consensus conference prior to the convening of the conference. The manuscript and recommendations were then presented at the conference for discussion. Recommendations were accepted if a consensus of the 28 experts attending the conference was reached. The discussions were also used to revise the manuscript into its final form.

CONCLUSIONS

The resulting article provides 17 recommendations for hypercoagulation testing in the setting of venous, arterial, or neurovascular thrombosis. The supporting evidence for test selection is analyzed and cited, and consensus recommendations for test selection are presented. Issues for which a consensus was not reached at the conference are also discussed.