Activated protein C resistance, factor V Leiden and peripheral vascular disease

Complications of Factor V Leiden in Adults Undergoing Noncardiac Surgical Procedures: A Systematic Review

Factor V Leiden is the commonest hereditary prothrombotic allele, affecting 1% to 5% of the world's population. The objective of this study was to characterize the perioperative and postoperative outcomes of patients with Factor V Leiden compared to patients without a diagnosis of hereditary thrombophilia. This was a focused systematic review of studies including adult (>18 years) patients with Factor V Leiden (heterozygous or homozygous) undergoing noncardiac surgery. Included studies were either randomized controlled trials or observational. The primary clinical outcomes of interest were thromboembolic events occurring from the perioperative period up to 1 year postoperatively, defined as deep venous thrombosis, pulmonary embolism, or other clinically significant thrombosis occurring during or after a surgical procedure. Secondary outcomes included cerebrovascular events, cardiac events, death, transplant-related outcomes, and surgery-specific morbidity. Pediatric and obstetrical patients were excluded, as were case reports and case series. Databases searched included MEDLINE and EMBASE from inception until August 2021. Study bias was assessed through the CLARITY (Collaboration of McMaster University researchers) Risk of Bias tools, and heterogeneity through analysis of study design and end points, as well as the I 2 statistic with its confidence interval and the Q statistic. A total of 5275 potentially relevant studies were identified, with 115 having full text assessed for eligibility and 32 included in the systematic review. On the whole, the literature suggests that patients with Factor V Leiden have an increased risk of perioperative and postoperative thromboembolic events compared to patients without the diagnosis. Increased risk was also seen in relation to surgery-specific morbidity and transplant-related outcomes, particularly arterial thrombotic events. The literature did not support an increased risk for mortality, cerebrovascular, or cardiac complications. Limitations of the data include predisposition toward bias due in many study designs and small sample sizes across the majority of published studies. Variable outcome definitions and durations of patient follow-up across different surgical procedures resulted in high study heterogeneity precluding the effective use of meta-analysis. Factor V Leiden status may confer additional risk for surgery-related adverse outcomes. Large, adequately powered studies are required to accurately estimate the degree of this risk by zygosity.

[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.

Links between arterial and venous disease

An increasing body of evidence suggests the likelihood of a link between arterial and venous disease. According to the results of recent studies, atherosclerosis and venous thromboembolism (VTE) share common risk factors, including age, obesity, diabetes mellitus and metabolic syndrome. Atherosclerosis has the potential to promote the development of thrombotic disorders in the venous system. Another scenario assumes that the two clinical conditions are simultaneously triggered by biological stimuli responsible for activating coagulation and inflammatory pathways in both the arterial and the venous system. Several recent studies have consistently shown that patients with VTE of unknown origin are at a higher risk of cardiovascular diseases, including atherosclerotic complications, than patients with secondary VTE and matched control individuals. Future studies are needed to clarify the nature of this association, to assess its extent and to evaluate its implications for clinical practice.

Venous thromboembolism and atherosclerosis: is there a link?

After the initial demonstration provided 4 years ago by a case-control study in the New England Journal of Medicine, numerous investigations have addressed the association between venous and arterial thrombotic disorders. According to the results of recent studies, the two conditions are likely to share common risk factors, including age, obesity, cigarette smoking, diabetes mellitus, arterial hypertension, hyperlipemia and metabolic syndrome. The nature of this association is unclear. On the one hand, atherosclerosis has the potential to promote the development of thrombotic disorders in the venous system. On the other hand, the two clinical conditions can be simultaneously triggered by biological stimuli responsible for activating coagulation and inflammatory pathways in both the arterial and the venous system. Based on the results of two population-based studies carried out in the USA, atherosclerosis is unlikely to constitute a risk factor for venous thromboembolic (VTE) disorders. Several recent studies have consistently shown that subjects with VTE of unknown origin are at a higher risk of subsequent arterial cardiovascular events than subjects with secondary VTE and matched control individuals. In conclusion, the separate nature of arterial and venous disorders has been challenged. Future studies are needed to clarify the nature of this association, to assess its extent, and to evaluate its implications for clinical practice.

Inherited Thrombophilia in Arterial Disease: A Selective Review

Thrombophilia may be defined as an acquired or congenital abnormality of hemostasis predisposing to thrombosis. Because arterial thrombosis is usually linked with classical risk factors such as smoking, hypertension, dyslipidemia, or diabetes, a thrombophilia workup is usually not considered in case of arterial thrombosis. The most accepted inherited hemostatic abnormalities associated with venous thromboembolism are factor V Leiden (FVL) and factor II (FII) G20210A mutations, as well as deficiencies in antithrombin (AT), protein C (PC), and protein S (PS). This review focuses on the link between these abnormalities and arterial thrombosis. Overall, the association between these genetic disorders and the three main arterial complications (myocardial infarction [MI], ischemic stroke [IS], and peripheral arterial disease [PAD]) is modest. Routine screening for these disorders is therefore not warranted in most cases of arterial complications. However, when such an arterial event occurs in a young person, inherited abnormalities of hemostasis seem to play a role, particularly when associated with smoking or oral contraceptive use. These abnormalities also seem to play a role in the risk of premature occlusion after revascularization procedures. Therefore thrombophilia tests may be informative in a very restricted population with arterial events. Anticoagulants rather than antiplatelet therapy may be preferable for these patients, although this remains to be proven.

Increased venous versus arterial thrombosis in the Factor V Leiden mouse

BACKGROUND

Deep vein thrombosis (DVT) occurs with high prevalence in association with the Factor V Leiden (R506Q) mutation, whereas most evidence suggests no correlation with clinical arterial thrombosis.

OBJECTIVE

This study compared arterial to venous thrombosis in the mutationally analogous Factor V Leiden mouse.

METHODS

Three separate vascular thrombosis models were evaluated in Fv(+/+) (wild-type), Fv(Q/+) (heterozygous) and Fv(Q/Q) (homozygous) Factor V Leiden mice.

RESULTS

In a FeCl(3)-induced arterial thrombosis model, no statistical differences among the three genotypes were found in the time to thrombotic occlusion. In contrast, Fv(Q/+) and Fv(Q/Q) mice demonstrated larger femoral vein thrombi at 30 and 60 min compared to wild-types, with Fv(Q/Q) mice having statistically larger thrombi than both wild-type and Fv(Q/+) mice at 10 and 60 min and 24 h (p<0.05). In a model of thrombotic occlusion following arterial and venous anastomotic repair, both Fv(Q/+) and Fv(Q/Q) mice had higher rates of venous thrombosis than wild-types, but only Fv(Q/Q) homozygotes showed a statistically greater arterial occlusion rate than wild-types.

CONCLUSION

The Factor V Leiden mouse demonstrated a greater propensity for venous vs. arterial thrombosis, paralleling clinical epidemiologic findings and supporting its use for research on deep vein thrombosis.

Factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations are not associated with chronic limb ischemia: the Linz Peripheral Arterial Disease (LIPAD) study

OBJECTIVE

Factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T mutations are considered risk factors for venous thromboembolism. It remains to be characterized whether the presence of these relatively common mutations poses a risk for peripheral arterial disease (PAD). Therefore, we intended to test, by conducting a case-control study, the hypothesis that PAD was associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations.

METHODS

The study comprised 433 patients admitted for inpatient diagnostics and treatment of PAD in patients with chronic limb ischemia. Patients with acute ischemia or malignancy were excluded. A total of 433 control subjects matched to the patients with PAD in a 1:1 design by sex, age (+/-2 years), and diabetes mellitus status were recruited. Factor V G1691A, prothrombin G20210A, and MTHFR C677T genotypes were assessed by polymerase chain reaction.

RESULTS

For the factor V G1691A polymorphism, the genotype frequencies in PAD patients were 92.8% GG (normal homozygotes = wild type) and 7.2% GA (mutant heterozygotes), and in control subjects they were 94.0% GG and 6.0% GA (chi 2 test; P = .493). The distribution of the prothrombin G20210A genotypes was 96.3% GG (normal homozygotes = wild type) and 3.7% GA (mutant heterozygotes) in PAD patients and was 97.2% GG and 2.8% GA in control subjects (chi 2 test; P = .442). Genotype frequencies for the MTHFR C677T polymorphism were 47.8% CC (normal homozygotes = wild type), 43.4% CT (mutant heterozygotes), and 8.8% TT (mutant homozygotes) in PAD patients, compared with 47.1% CC, 44.1% CT, and 8.8% TT in control subjects (chi 2 test; P = .977). Accordingly, as determined by logistic regression analysis, no significant odds ratios for heterozygous or homozygous genotypes of the three polymorphisms could be observed.

CONCLUSIONS

PAD was not associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations in the population studied. Thus, there is no indication that of one of these mutations may be a risk factor for chronic limb ischemia. However, the role of these mutations in acute limb ischemia remains to be clarified.

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.

Inherited thrombophilia

There is limited evidence that certain heritable thrombophilias may be associated with an increased risk of peripheral vascular disease. In particular, increased activated protein C resistance and FV Leiden have been described as being more prevalent in patients with peripheral arterial disease. There is no clear evidence at present, however, that other heritable thrombophilias are associated with an increased risk of arterial occlusive disease. Heritable thrombophilia, in particular FV Leiden, may be associated with an increased risk of vascular reconstruction failure but there is a lack of evidence to show that intervention with anticoagulants influences the outcome of graft surgery in these patients.

Factor V Leiden and perioperative risk

Factor V Leiden (FVL) is the most common known inherited cause of thrombophilia; it is present in approximately 5% of the Caucasian population. Although the risk of venous thrombosis associated with this polymorphism in various medical settings is well described, its effect on perioperative risk is only beginning to be explored. Specifically, there are few studies addressing the potential risks of FVL in the surgical population, in which both hemorrhagic and thrombotic complications convey substantial clinical and economic significance. There are speculations and unproven hypotheses regarding FVL in this population, and these therefore highlight the need to comprehensively address this issue. This review will describe the physiology of the FVL mutation, briefly clarify its risk in the nonsurgical setting, and assess current data regarding FVL in noncardiac and cardiac surgery. Finally, a summary of current clinical evidence and a plan for more detailed investigation of this potentially significant risk factor will be proposed.

Are National Cardiac Guidelines being Applied by Vascular Surgeons?

INTRODUCTION

National cardiac guidelines recommend that patients with intermittent claudication should be managed in the same way as those with established coronary heart disease. This survey aimed to determine the attitudes of vascular consultants to risk factor management in new patients attending their out-patient clinic.

METHODS

An anonymous postal questionnaire was sent to all 394 members of the Vascular Surgical Society in June 2002. Questions were asked about the following measures: serum cholesterol levels, the presence of diabetes, antiplatelet therapy, exercise regimens, blood pressure, thrombophilia, smoking and the availability of local guidelines and expertise.

RESULTS

A response rate of 65% was obtained. Most (85%) consultants would measure a random cholesterol, but 34% would only treat claudicants if the cholesterol was greater than 5.5 mmol/l. Furthermore, 23% would inappropriately use diet alone as initial cholesterol lowering therapy. Over a quarter of consultants would not screen for diabetes or measure blood pressure. Nearly all (99%) would recommend aspirin and 66% would recommend nicotine replacement therapy. Only 55% had access to a smoking cessation clinic, and 34% to a formal exercise program. The majority (56%) did not have local risk factor management guidelines, only 16% had access to a vascular physician, and 65% would prefer to have this expertise available for difficult cases.

DISCUSSION

Management of major risk factors was found to be sub-optimal. Thus guidelines for the prevention of coronary disease in clinical practice are not being applied to claudicants.

An association between atherosclerosis and venous thrombosis

BACKGROUND

In about a third of patients with venous thromboembolism, the cause of the disorder is unexplained. In patients with atherosclerosis, activation of both platelets and blood coagulation and an increase in fibrin turnover are detectable, which may lead to thrombotic complications. Whether atherosclerosis is associated with an increased risk of venous thrombosis is unknown.

METHODS

We performed ultrasonography of the carotid arteries in 299 unselected patients who had deep venous thrombosis of the legs without symptomatic atherosclerosis and in 150 control subjects. Patients with spontaneous thrombosis, patients with secondary thrombosis from acquired risk factors, and control subjects were assessed for plaques.

RESULTS

At least one carotid plaque was detected in 72 of the 153 patients with spontaneous thrombosis (47.1 percent; 95 percent confidence interval, 39.1 to 55.0), 40 of the 146 with secondary thrombosis (27.4 percent; 95 percent confidence interval, 20.2 to 34.6), and 48 of the 150 control subjects (32.0 percent; 95 percent confidence interval, 24.5 to 39.5). The odds ratios for carotid plaques in patients with spontaneous thrombosis, as compared with patients with secondary thrombosis and with controls, were 2.3 (95 percent confidence interval, 1.4 to 3.7) and 1.8 (95 percent confidence interval, 1.1 to 2.9), respectively. In a multivariate analysis that accounted for risk factors for atherosclerosis, the strength of this association did not change.

CONCLUSIONS

There is an association between atherosclerotic disease and spontaneous venous thrombosis. Atherosclerosis may induce venous thrombosis, or the two conditions may share common risk factors.

Elevated prothrombin and activated protein C resistance in patients with thoracic aortic atheroma

Patients with protruding aortic atheroma containing mobile emboli are at risk for peripheral emboli and stroke. This risk may possibly be reduced by anticoagulation, but whether or not such patients have an increased prevalence of thrombotic risk factors has not been previously determined. Twenty-two patients were studied (11 with protruding thoracic aortic atheromas and superimposed mobile thrombi on transesophageal echocardiography were compared to 11 age-matched controls). The authors evaluated activated protein C resistance (APC-R) by measuring the prolongation of the partial thromboplastin time (PTT) in response to activated protein C (APC). Concentrations of fibrinogen, antithrombin III (AT III), factor II, factor V, and D-dimer were also determined in all patients. There was significant resistance to APC (a smaller prolongation in PTT) in patients with atheromas and thrombi. They also had significantly higher concentrations of factor II. Factor V and fibrinogen were higher, and AT III lower, in patients than in controls; however, these latter differences did not reach statistical significance. Patients with aortic atheroma and mobile thrombi may have an increased prevalence of thrombotic risk factors. There is significantly increased resistance to activated protein C in patients with protruding atheroma and mobile thrombi in their thoracic aorta. There was also a trend toward elevated fibrinogen, homocysteine, and apo (a) concentrations as well as lower antithrombin III concentrations in these patients.

Thrombophilia, polymorphisms, and vascular disease

Thrombophilia traditionally refers to rare inherited defects leading to enhanced coagulation, especially of the venous system. In recent years, a broader search for genetic polymorphisms of prothrombotic genes has been carried out to determine the relative impact on venous and arterial thrombosis. The bulk of evidence is drawn from numerous, often small, heterogeneous, case control association studies, with a variety of end points (deep venous thrombosis, myocardial infarction, or stroke). The data are often conflicting and inconclusive with only factor V Leiden and prothrombin polymorphisms having clear associations with venous thrombosis. Many of the polymorphisms interact with established cardiovascular risk factors, in particular smoking, to increase greatly the risk of a thrombotic episode. Future studies will need to consider the confounding factors of sample size, race, and clinical end points as well gene-environment interactions.

Unlike thrombin, protein C and activated protein C do not affect vascular tone

Because plasma levels of protein C (PC) or activated protein C (APC) are altered in certain diseases associated with vascular dysfunction, and APC has therapeutic potential in preventing microvascular coagulation in severe sepsis, potential vascular effects of PC and APC were compared to those of the vasoactive peptide, thrombin. Thrombin was a more potent relaxant agonist than contractile agonist in aorta. Unlike thrombin, cumulatively administered APC (10(-9)-10(-7) M) did not exert vascular effects in rat or rabbit aorta. Noncumulative challenge of PC (10(-7) M) and APC (8 x 10(-8) M) also did not contract rat or rabbit aortae, either with or without endothelium. Likewise, the same concentrations of PC and APC also did not relax norepinephrine-induced (10(-7) M) vascular tone in either rat or rabbit aortae. Thus, in contrast to thrombin, PC and APC failed to modulate vascular tone, suggesting that the therapeutic use of APC is unlikely to be accompanied by any direct effects on vascular motility.

The Leiden mutation of coagulation factor V in Hungarian SLE patients

We studied the prevalence and the effect of coagulation factor V Leiden mutation on the occurrence of thrombotic episodes in 120 Hungarian patients having systemic lupus erythematosus (SLE) with or without antiphospholipid antibody. The frequency of the factor V Leiden mutation in Hungarian SLE patients was 13%, which is comparable with those found previously in a healthy Caucasian population. The incidence of venous thrombosis among factor V Leiden carriers has been found to be higher (odds ratio [OR] 1.7) than it is in patients without Leiden mutation (38% vs 29%). In addition, the frequency of venous thrombosis in the heterozygous SLE patients (OR 8.4 [confidence interval (CI) 0.8-83.9] P = 0.06) is dependent on the coexistence of other risk factors, such as antiphospholipid antibody. Moreover, among heterozygous factor V SLE patients, the Leiden mutation could explain the tendency to have significantly higher prevalence of fetal losses (OR 3.9 [CI 1.2-12.0] P = 0.02) and higher prevalence of cerebrovascular lesions, cardiac valvular abnormalities, and Raynaud's syndrome than that found in individuals without factor V Leiden mutation of those having antiphospholipid antibody. Systemic lupus erythematosus patients with combined defects suffer more severely from thrombosis than those with a single risk factor do, suggesting that thrombophilia is a multifactorial disorder in SLE, also. Although, the factor V Leiden mutation does not seem to be a significant risk factor for venous thrombosis in SLE, these data demonstrate that Leiden mutation can be regarded as an additive thrombogenic factor providing higher predisposition to several vasoocclusive disorders in SLE.

Prevalence and outcome of activated protein C resistance in patients after peripheral arterial bypass grafts

The association of activated protein C resistance with peripheral arterial bypass graft patency was assessed. A retrospective cohort study of consecutive first-time femoro-popliteal or femoro-distal bypasses performed in patients living within the boundaries of the Area Health Service was performed. Of 242 patients eligible for inclusion, 73 had died, nine refused to participate and 40 were lost to follow-up. Activated protein C resistance was present in nine (7.5%) of the 120 patients tested. In the study group, smoking at the time of surgery, female gender and the use of prosthetic grafts were significantly associated with graft failure on univariate Cox regression analysis, but activated protein C resistance was not. After accounting for confounders, there was a trend (P = 0.098) for activated protein C resistance to be associated with graft failure (OR 2.90, 95% CL 0.82-10.3). Patients who died or who were lost to follow-up had significantly earlier operation dates than those who remained alive or tested for activated protein C resistance. However, there was also a highly significant (P = 0.006) trend for activated protein C resistance in patients who had undergone surgery closer to the end of the study period. Six of the nine patients with activated protein C resistance underwent surgery in the last 10 months of the review period and only three activated protein C resistance patients had a graft patent for more than 8 months. The prevalence of activated protein C resistance in patients undergoing peripheral arterial bypass grafting is greater than in the general population. There was a trend for activated protein C resistance to be associated with graft failure. A significantly higher proportion of patients with activated protein C resistance was found with more recently performed surgery. The observed results could be accounted for by excess mortality in patients with activated protein C resistance. This hypothesis requires testing prospectively.

Heterogeneous ethnic distribution of the factor v leiden mutation

Inherited resistance to activated protein C caused by the factor V Leiden (FVL) mutation is the most common genetic cause of venous thrombosis yet described, being found in 20-60% of patients with venous thrombophilia. A relationship between the FVL mutation and an increased predisposition to arterial thrombosis in young women was recently reported. We assessed the prevalence of the FVL mutation in 440 individuals (880 chromosomes) belonging to four different ethnic groups: Caucasians, African Blacks, Asians and Amerindians. PCR amplification followed by MnlI digestion was employed to define the genotype. The FVL mutation was found in a heterozygous state in four out of 152 Whites (2.6%), one out of 151 Amerindians (0.6%), and was absent among 97 African Blacks and 40 Asians. Our results confirm that FVL has a heterogeneous distribution in different human populations, a fact that may contribute to geographic and ethnic differences in the prevalence of thrombotic diseases. In addition, these data may be helpful in decisions regarding the usefulness of screening for the FVL mutation in subjects at risk for thrombosis.

Risk factors for premature atherosclerosis

OBJECTIVES

to investigate the prevalence of risk factors in patients with premature atherosclerosis.

DESIGN

retrospective controlled study.

MATERIALS

135 consecutive patients with premature atherosclerosis </= 55 years (group I) were investigated. A control group comprised 107 consecutive patients >/= 65 years (group II) with atherosclerosis. Statistical analysis was performed with Chi-squared test and logistic regression analysis.

RESULTS

group I versus group II: diabetes 11% vs. 27% (p=0.001), smoking 84% vs. 67% (p=0.002), hypertension 36% vs. 58% (p=0.001), hypercholesterolaemia 47% vs. 34% (p=0.04), family history of cardiovascular disease 53% vs. 42% (p=0.08). In group I hyperhomocysteinaemia was present in 24 of the 108 patients tested, anticardiolipin antibodies were present in four of the 34 tested and coagulation abnormalities were found in four of the 22 patients tested.

CONCLUSION

the difference in the prevalence of the different risk factors between the two groups suggests that either certain risk factors are more likely to cause premature atherosclerosis, or that other risk factors must be present in addition to the known risk factors in order to induce premature atherosclerosis.