Intermittent claudication and risk of cardiovascular events

Dietary antioxidant intake increases ankle brachial pressure index in men but not in women: a cross-sectional study

Objective

Atherosclerosis is a significant cause of cardiovascular and cerebrovascular diseases, with a greater impact on men than women. Dietary antioxidant intake is inversely related to the risk of atherosclerosis development. We aimed to investigate the association between dietary composite antioxidant intake and the ankle brachial pressure index (ABPI). The ABPI is not only used for assessing the progression of arterial lesions but also for stratifying the risk of atherosclerotic disease.

Methods

We conducted a cross-sectional analysis involving 1,049 participants from the National Health and Nutrition Examination Survey (NHANES). We examined six antioxidants (zinc, selenium, carotenoids, and vitamins A, C, and E) and a composite dietary antioxidant index (CDAI) derived from these antioxidants as exposure variables. The primary outcomes encompassed cardio-metabolic parameters, including body mass index (BMI), body fat mass (BFM), systolic and diastolic blood pressure, triglycerides, HDL and LDL cholesterol, C-reactive protein, and the Ankle-Brachial Pressure Index (ABPI). Associations and interactions between variables were assessed using linear regression analyses. Moreover, mediation and moderation analysis is employed.

Results

Hierarchical multiple regression analysis revealed that among men, dietary intake of zinc, selenium, and vitamin A remained positively associated with a higher ABPI even after adjusting for covariates. Conversely, in the stratified regression analysis based on CDAI quartiles, a U-shaped association between CDAI and ABPI was suggested. Notably, no significant association between dietary antioxidant intake and ABPI was observed among women. CDAI, intake of Vitamin A, Vitamin C, and Vitamin E do not influence all-cause death through mediation by abpi, but rather have a direct effect on all-cause death. Moreover, there is a significant interaction between the intake of Vitamin A and gender, where a daily intake of Vitamin A more than 776 ug is especially beneficial for women.

Conclusion

The combined intake of nutrients with antioxidant properties may prevent the initiation and progression of atherosclerosis and influence the outcome in a sex-specific manner.

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.

Physical Activity Levels in Peripheral Artery Disease Patients

Background

Increases in daily physical activity levels is recommended for patients with peripheral artery disease (PAD). However, despite this recommendation, little is known about the physical activity patterns of PAD patients.

Objective

To describe the physical activity patterns of patients with symptomatic peripheral artery (PAD) disease.

Methods

This cross-sectional study included 174 PAD patients with intermittent claudication symptoms. Patients were submitted to clinical, hemodynamic and functional evaluations. Physical activity was objectively measured by an accelerometer, and the time spent in sedentary, low-light, high-light and moderate-vigorous physical activities (MVPA) were obtained. Descriptive analysis was performed to summarize patient data and binary logistic regression was used to test the crude and adjusted associations between adherence to physical activity recommendation and sociodemographic and clinical factors. For all the statistical analyses, significance was accepted at p < 0.05.

Results

Patients spent in average of 640 ± 121 min/day, 269 ± 94 min/day, 36 ± 27 min/day and 15 ± 16 min/day in sedentary, low-light, high-light and MVPA, respectively. The prevalence of patients who achieved physical activity recommendations was 3.4%. After adjustment for confounders, a significant inverse association was observed between adherence to physical activity recommendation and age (OR = 0.925; p = 0.004), while time of disease, ankle brachial index and total walking distance were not associated with this adherence criteria (p > 0.05).

Conclusion

The patterns of physical activity of PAD patients are characterized by a large amount of time spent in sedentary behaviors and a low engagement in MVPA. Younger patients, regardless of the clinical and functional factors, were more likely to meet the current physical activity recommendations.

Clinical implications of fetuin-A

Fetuin-A, also termed alpha2-Heremans-Schmid glycoprotein, is a 46kDa hepatocyte derived protein (hepatokine) and serves multifaceted functions.

Disease-specific characteristics of vascular cell adhesion molecule-1 levels in patients with peripheral artery disease

Peripheral arterial disease (PAD) is one of the most common manifestations of systemic atherosclerosis. The prevalence of unrecognized PAD is high, leading to a lack of opportunity to detect subjects at a high risk for cardiovascular events. Inflammatory processes play an important role in the disease initiation as well as in the disease progression. Vascular cell adhesion molecule 1 (VCAM-1), a biomarker of endothelial dysfunction, appears to be an important mediator in inflammatory processes. Therefore, we hypothesized that in patients with PAD, circulating VCAM-1 might be elevated due to its function in mediating adhesion of immune cells to the vascular endothelium in the process of endothelial dysfunction and inflammation, and, therefore, applicable as a diagnostic biomarker. A total of 126 non-consecutive patients were enrolled in this study, of whom 51 patients had typical clinical manifestations of PAD and as controls 75 patients with no history of PAD or cardiovascular disease. All serum samples were obtained either during hospitalization or during out-patient visits and analyzed for VCAM-1 by the ELISA. Compared with controls, median levels of VCAM-1 were significantly elevated in patients suffering from PAD (953 vs. 1352 pg/ml; p < 0.001). Furthermore, VCAM-1 appeared to be highly discriminative for the detection of PAD (AUC = 0.76; CI 0.67-0.83). We could not observe dynamics related to increasing disease stages according to Rutherford classes in patients with apparent PAD. VCAM-1 was shown to be a potential discriminator and biomarker for the severity of systemic atherosclerosis. In a logistic regression analysis, VCAM-1 was robustly associated with the diagnosis of PAD, even after correction for clinically relevant cofounders (namely age, arterial hypertension, diabetes and LDL levels). Thusly, VCAM-1 might serve as a biomarker for PAD screening and detection.

Peripheral artery disease: epidemiology and global perspectives

Global populations are undergoing a major epidemiological transition in which the burden of atherosclerotic cardiovascular diseases is shifting rapidly from high-income to low-income and middle-income countries (LMICs). Peripheral artery disease (PAD) is no exception, so that greater focus is now required on the prevention and management of this disease in less-advantaged countries. In this Review, we examine the epidemiology of PAD and, where feasible, take a global perspective. However, the dearth of publications in LMICs means an unavoidable over-reliance on studies in high-income countries. Research to date suggests that PAD might affect a greater proportion of women than men in LMICs. Although factors such as poverty, industrialization, and infection might conceivably influence the development of PAD in such settings, the ageing of the population and increase in traditional cardiovascular risk factors, such as smoking, diabetes mellitus, and hypertension, are likely to be the main driving forces.

Falsely high ankle-brachial index predicts major amputation in critical limb ischemia

Falsely high ankle-brachial index (ABI) values are associated with an adverse clinical outcome in diabetes mellitus. The aim of the present study was to verify whether such an association also exists in patients with chronic critical limb ischemia (CLI) with and without diabetes. A total of 229 patients (74 ± 11 years, 136 males, 244 limbs with CLI) were followed for 262 ± 136 days. Incompressibility of lower limb arteries (ABI > 1.3) was found in 45 patients, and was associated with diabetes mellitus ( p = 0.01) and renal insufficiency ( p = 0.035). Limbs with incompressible ankle arteries had a higher rate of major amputation ( p = 0.002 by log-rank). This association was confirmed by multivariate Cox regression analysis (relative risk [RR] 2.67; 95% CI 1.27-5.64, p = 0.01). The relationship between ABI > 1.3 and amputation rate persisted after subjects with diabetes and renal insufficiency had been removed from the analysis (RR 3.85; 95% CI 1.25-11.79, p = 0.018). Dividing limbs with measurable ankle pressure according to tertiles of ABI, the group in the second tertile (0.323 ≤ ABI ≤ 0.469) had the lowest amputation rate (4/64, 6.2%), and a U-shaped association between the occurrence of major amputation and ABI was evident. No association was found between ABI and mortality. In conclusion, this study demonstrates that falsely high ABI is an independent predictor of major amputation in patients with CLI.

Decrease in circulating dendritic cell precursors in patients with peripheral artery disease

Peripheral artery disease (PAD) is a common manifestation of atherosclerosis. Inflammation is important for initiation and progression of the disease. Dendritic cells (DCs) as antigen-presenting cells play an important role in the immune system. Therefore, we hypothesize that, in patients with PAD, DCPs might be reduced in blood due to their recruitment into the vascular wall and induce a proinflammatory response. The numbers of myeloid DCPs, plasmacytoid DCPs, and total DCPs were analyzed by flow cytometry in blood of patients with PAD (n = 52) compared to controls (n = 60). Femoralis plaques (n = 12) of patients who underwent surgery were immunostained for CD209 and CD83 (mDCs) as well as CD304, CD123 (pDCs), and HLA-DR. In patients with PAD, a significant decrease in mDCPs, pDCPs, and tDCPs was observed. In immunostaining, markers indicative for mDCs (CD209: 16 versus 8 cells/0.1 mm(2), P = 0.02; CD83: 19 versus 5 cells/0.1 mm(2), P = 0.03) were significantly elevated in femoralis plaques compared to control vessels. We show for the first time that mDCPs, pDCPs, and tDCPs are significantly reduced in patients with PAD. Immunohistochemical analysis unraveled that the decrease in DCPs might be due to their recruitment into atherosclerotic plaques.

Predictive value of elevated neutrophil to lymphocyte ratio for long-term cardiovascular mortality in peripheral arterial occlusive disease

BACKGROUND

Peripheral arterial occlusive disease (PAOD), which is common in male gender and elderly population, is related with increased cardiovascular mortality and morbidity. Neutrophil to lymphocyte ratio (NLR) has been found to be an independent predictor of cardiovascular mortality in atherosclerosis. The aim of the present study was to investigate the association between NLR and cardiovascular mortality both in patients with intermittent claudication and critical limb ischemia.

METHODS

In a retrospective study, 593 consecutive patients who had been admitted to the inpatient ward of the vascular department of a large tertiary training and research hospital with diagnosis of symptomatic PAOD between May 2009 and September 2012 were included. Patients were divided into two groups according to their NLR as follows: high NLR (NLR>3.0) and low NLR (NLR ≤ 3.0) groups.

RESULTS

During the course of the present study [median follow-up period of 20 months (interquartile range, 12-27)], 75 deaths occurred out of 508 patients (14.8%). Cardiovascular mortality was found to be significantly higher in elevated NLR group (n = 43) as compared to low NLR group (n = 32) (23.6% vs 9.8%, respectively; p < 0.001). Even after adjustment of various risk factors, NLR > 3 and age were found as independent predictors of long-term cardiovascular mortality in Cox regression analysis [hazard ratios (95% confidence interval), 2.04 (1.26-3.30) and 1.04 (1.01-1.07), p = 0.004 and p = 0.004, respectively].

CONCLUSION

We demonstrated that an increased NLR was related with higher cardiovascular mortality in patients with PAOD, who were admitted with critical limb ischemia or intermittent claudication. NLR, which reflects the patient's inflammatory status, is an inexpensive and readily available biomarker that provides an additional level of risk stratification beyond that provided by conventional risk scores in predicting long-term cardiovascular mortality in PAOD.

A decline in walking distance predicts long-term outcome in patients with known or suspected peripheral artery disease

AIM

To assess the predictive value of a decline in total walking distance and ankle brachial index (ABI) on all-cause mortality and cardiac death in patients with known or suspected peripheral artery disease.

METHODS

Two hundred and sixty-one patients, who performed single-stage treadmill walking test twice to evaluate their peripheral artery disease, were enrolled in an observational study. Patients who underwent surgery during follow-up were excluded. Delta total walking distance and delta resting and exercise ABI consisted of the difference between the first and the second test. All three variables were categorized into two groups: stable/improvement or a decline.

RESULTS

The mean follow-up period was 6 years. At both 5 years and total follow-up, a decline in total walking distance was independent and highly associated with an increased mortality risk and cardiac death [hazard ratio: 2.31 (95% confidence interval 1.35-3.96); hazard ratio: 3.55 (95% confidence interval: 1.53-8.21), respectively]. A decline in resting or exercise ABI after adjustment for delta walking distance was not significantly associated with all-cause mortality or cardiac death.

CONCLUSION

A decline in total walking distance in single-stage treadmill exercise tests is a strong prognostic predictor of all-cause mortality and cardiac death in the short term and long term.

The prognostic impact of general and abdominal obesity in peripheral arterial disease

OBJECTIVE

Obesity is an independent cardiovascular risk factor, but its prognostic role in patients with peripheral arterial disease (PAD) is not well defined. Accordingly, we assessed the impact of body mass index (BMI) and waist circumference (WC) on cardiovascular risk in a homogeneous cohort of PAD patients.

METHODS

BMI and WC were measured in 190 consecutive PAD patients with ABI <0.90, referred to our university hospital for intermittent claudication. The occurrence of cardiac, cerebrovascular and peripheral events was prospectively assessed. The ability to classify risk was determined by calculating the hazard ratios (HRs) and c-statistics.

RESULTS

During a median follow-up of 31.5 months, 63 patients (33.2%) had a cardiovascular event. Considered as continuous variables, both adiposity indices were significantly associated with increased cardiovascular risk, even after adjustment for possible confounding factors (HR=1.08, 95% CI 1.01-1.15, P=0.045 for BMI and HR=1.04, 95% CI 1.01-1.07, P=0.004 for WC). When BMI and WC were included together in a fully adjusted Cox model, the significant association between BMI and cardiovascular risk disappeared (HR=0.98, 95% CI 0.88-1.10, P=0.772), whereas WC remained significantly associated with a worse outcome (HR=1.04, 95% CI 1.01-1.08, P=0.033). The better discriminative ability of WC vs BMI was confirmed by the c-statistic, which was significantly higher for WC (0.63, 95% CI 0.56-0.70) than for BMI (0.56, 95% CI 0.51-0.63, P=0.038).

CONCLUSIONS

Abdominal obesity and, to a lesser degree, general obesity worsen the prognosis of PAD patients independently of possible confounding factors. Weight reduction should be integrated in the active management of these patients.

Risk assessment in the patient with established peripheral arterial disease

Office-based cardiovascular risk prediction continues to challenge practitioners in primary and secondary risk stratification settings. In patients with established peripheral arterial disease (PAD), the risk of cardiovascular events (i.e. death or morbidity due to coronary heart disease and/or cerebrovascular disease) is high, yet traditional risk factors and the ankle-brachial index (ABI) do not provide a complete secondary risk prediction. In this population, office-based cardiovascular risk stratification may be improved by surrogate markers of the systemic atherosclerotic burden, as well as markers of systemic inflammation. This review will evaluate the utility of the ABI, clinical stage of disease, and the emerging role of C-reactive protein (CRP) and other inflammatory markers in secondary risk prediction in PAD. Defining which patients are in the highest category of risk may direct health care providers to emphasize secondary preventive measures, and facilitate patient adherence to recommended medical therapies and smoking cessation.

Endothelial dysfunction: a key to the pathophysiology and natural history of peripheral arterial disease?

Dysfunctional endothelium plays a crucial role in all stages of atherosclerosis and thus the accurate assessment of this organ is a valuable tool, especially if such assessments are clinically relevant. In peripheral arterial disease (PAD), which affects about 27 million of individuals in Europe and North America, increased plasma markers of endothelial dysfunction and reduced endothelium-mediated vasoreactivity, are associated with both the severity and the extent of atherosclerosis in the arteries of the lower limbs, is exacerbated by acute exercise, may help identify subjects with subclinical coronary artery disease, and portends a worse outcome. As a result, endothelial dysfunction is a promising target for therapeutic interventions in PAD. Large clinical trials are needed to verify whether affected individuals with depressed endothelial function benefit from specific treatments.

Metabolic syndrome increases the risk of significant coronary artery involvement in patients with peripheral artery disease

BACKGROUND

Peripheral artery disease is a common condition, mainly associated with clinical cardiovascular risk factors. Patients with peripheral artery disease suffer from coronary artery disease-related complications. On the other hand, metabolic syndrome, as a constellation of specific risk factors, represents a risk factor for cardiovascular mortality. Metabolic syndrome might increase the risk of significant coronary artery disease in patients with peripheral artery disease. We aimed to examine the association of metabolic syndrome with the angiographically shown coronary artery involvement in patients with peripheral artery disease.

METHODS

Two hundred and forty-seven patients with peripheral artery disease (mean age 60+/-9.5 years, 223 men/24 women), who were referred to coronary angiography, were evaluated. The resting ankle-brachial pressure index was measured with the patient in supine position. Patients with >70% diameter stenosis were considered to have significant coronary artery disease.

RESULTS

In all, there were 223 male/24 female patients with mean ankle-brachial pressure index of 0.7+/-0.2, and mean age of 60+/-9.5 years. Metabolic syndrome was present in 53% (n=131) of all patients. Significant coronary artery disease was more frequently encountered in patients with peripheral artery disease and metabolic syndrome than in those without metabolic syndrome (73.3 vs. 40.5%, P<0.001). The presence of metabolic syndrome increased the risk of having significant coronary artery disease in patients with peripheral artery disease by 4.027 fold. Lower ankle-brachial pressure index (P=0.038, B=2.567), older age (P<0.001, B=1.075), presence of metabolic syndrome (P=0.015, B=2.247), and presence of diabetes mellitus (P<0.001, B=1.293) were found to be independent predictors of significant coronary artery disease in patients with peripheral artery disease in multivariable regression.

CONCLUSION

Metabolic syndrome seems to increase the risk of significant coronary artery disease in patients with peripheral artery disease.

Cellular adhesion molecules and peripheral arterial disease

Cellular adhesion molecules (CAMs), by mediating the recruitment of circulating leukocytes to the blood vessel wall and their subsequent migration into the subendothelial spaces, play a crucial role in all stages of atherosclerosis. Soluble forms of CAMs, probably derived from proteolytic shedding, are present in the circulation and their blood levels parallel the amount expressed on the cell surface. In patients with peripheral arterial disease (PAD), increased levels of soluble CAMs have been found during exercise-induced claudication, are associated with the presence, the severity and the extent of atherosclerosis in the arteries of the lower limbs, and portend a worse outcome. These findings have provided new insights into the pathophysiology of PAD and its consequences. However, further large population studies are needed to firmly establish whether increased levels of circulating CAMs give additive information to current risk assessment approaches, and to verify whether PAD patients with elevated levels of circulating CAMs would benefit from any specific therapy.

Does nutrition have a role in peripheral vascular disease?

Peripheral vascular disease (PVD) is a manifestation of systemic atherosclerosis in the lower limbs, and PVD patients have a 3- to 5-fold increased risk of cardiovascular mortality compared with age-matched controls. Nevertheless, recent reports show how PVD patients are undertreated with regard to CVD risk-factor reduction and the use of lipid-lowering or antiplatelet drugs. There is appreciable evidence that demonstrates the beneficial effects of certain nutrients and dietary habits in the prevention of CVD, but there has been little attention paid to the role of nutrients in PVD. The purpose of the present review is to provide an overview of our understanding of how foods could possibly benefit PVD. In the last few decades, several nutrients have arisen as potentially health-promoting in PVD. While nutritional interventions in PVD show positive clinical effects for fish oil, carnitine or vitamin E, others such as olive oil or vitamin C seem to interact only at a biochemical level by decreasing risk factors. Moreover, only epidemiological associations exist for the potential role of fibre, folates or vitamin B6 in this disease. In all cases, the limited data available provide no clear-cut evidence in favour of the clinical benefit of nutritional interventions aimed at reducing risk factors and ameliorating symptoms in PVD patients. No practical recommendations can be given at this stage, and further studies are clearly needed.

Impact of C-reactive protein on the likelihood of peripheral arterial disease in United States adults with the metabolic syndrome, diabetes mellitus, and preexisting cardiovascular disease

We sought to determine, in United States (US) patients with the metabolic syndrome (MS), diabetes mellitus (DM), or preexisting cardiovascular disease, whether higher levels of C-reactive protein (CRP) would identify those with an increased likelihood of peripheral arterial disease (PAD). In a cross-sectional evaluation of the National Health and Nutrition Examination Survey (NHANES), 1999 to 2000, of 1,600 adults (representing a US population of 62.9 million) aged > or =40 years who had valid ankle-brachial index measurements available, subjects were categorized as having MS (without DM), DM, preexisting cardiovascular disease, or none of these conditions. The presence of PAD was defined as an ankle-brachial index <0.9. Subjects were also divided into groups according to CRP levels that were low (<1 mg/L), intermediate (1 to 3 mg/L), and elevated (>3.0 mg/L). Weighted multiple logistic regression analysis examined the odds of PAD by CRP group and disease category compared with the reference group of subjects who did not have MS, DM, or cardiovascular disease and had a CRP level of <1 mg/L. Those with MS (including DM) had an increased likelihood of PAD (odds ratio 4.8, 95% confidence interval 1.4 to 16.1, p = 0.01) as did those with MS without diabetes and an elevated CRP level (odds ratio 3.9, 95% confidence interval 1.1 to 14.6, p = 0.04); those with DM and an elevated CRP had the highest likelihood of PAD (odds ratio 8.6, 95% confidence interval 2.2 to 34.0, p = 0.001). In conclusion, the likelihood of PAD in US adults with MS and DM is enhanced by elevated CRP levels.

Endothelial dysfunction and cardiovascular risk prediction in peripheral arterial disease: additive value of flow-mediated dilation to ankle-brachial pressure index

BACKGROUND

Endothelial dysfunction plays a key role in atherogenesis. We prospectively investigated the impact of noninvasive measurement of endothelial function on cardiovascular risk in peripheral arterial disease (PAD). The study was specially aimed at assessing whether brachial artery flow-mediated dilation (FMD) added to the predictive value of ankle-brachial pressure index (ABPI).

METHODS AND RESULTS

Of 131 patients monitored for a mean of 23+/-10 months, 18 had a coronary event, 12 a cerebrovascular event, and 9 a peripheral event. The median FMD was lower in patients with an event than in those without (5.8% versus 7.6%, P<0.05), whereas vasodilation to nitroglycerin was similar in the two groups. The cardiovascular event rate was higher in patients with FMD below the median versus those with FMD above the median (P<0.001 by log-rank test). In a Cox proportion hazard model, independent predictors of events were FMD below the median (P<0.01), ABPI below the median (P<0.01), and previous stroke (P<0.02). Similar results were obtained when peripheral events were excluded from the analysis. Below-median ABPI and FMD combined was more accurate in predicting risk (relative risk [RR] 13.0; 95% CI, 3.0 to 56.2; P<0.01) than ABPI (RR, 6.4; 95% CI, 1.4 to 29.1; P<0.02) and FMD (RR, 4.8; 95% CI, 1.1 to 23.3; P<0.05) alone.

CONCLUSIONS

A low brachial artery FMD is an independent predictor of cardiovascular risk in patients with PAD and adds to the prognostic value of ABPI, which is currently the most powerful prognostic indicator in PAD.

Endothelial dysfunction in peripheral arterial disease is related to increase in plasma markers of inflammation and severity of peripheral circulatory impairment but not to classic risk factors and atherosclerotic burden

OBJECTIVE

We undertook this study to evaluate in patients with peripheral arterial disease (PAD) the relationship of endothelial dysfunction, which is directly related to progression and clinical complications of atherosclerosis, with variables including classic risk factors, inflammation, severity of peripheral circulatory impairment, and atherosclerotic burden.

METHODS

This cross-sectional study included outpatients seen in an academic angiologic unit. Eighty-eight consecutive patients with PAD (ankle/brachial index [ABI] < 0.90) were studied. The control group consisted of 30 age-matched and sex-matched healthy subjects. Main outcome measures were endothelial function in the form of brachial artery flow-mediated dilation (FMD), plasma levels of C-reactive protein (CRP) and fibrinogen, severity of PAD according to ABI, and atherosclerotic burden, ie, atherosclerosis in one leg or in two or more other sites.

RESULTS

Compared with patients with FMD greater than 6.2% (ie, 5th percentile of FMD in control subjects), patients with FMD less than 6.2% had a similar prevalence of classic risk factors but higher median levels of CRP (1.6 vs 6.0 mg/L; P <.01) and fibrinogen (200 vs 374 mg/dL; P <.01). The two inflammatory markers were negatively correlated with FMD (P <.01). ABI was higher in patients with FMD greater than 6.2% than in those with worse endothelial function (0.72 +/- 0.15 vs 0.62 +/- 16; P <.01); there was no difference with respect to atherosclerotic burden. Multivariate analysis showed that the association of CRP, fibrinogen, and ABI with FMD less than 6.2% was unrelated to classic risk factors. In a second model, which included CRP, fibrinogen, and ABI, all three variables were independently related to FMD less than 6.2%.

CONCLUSION

Inflammation and severity of circulatory impairment are implicated in the pathophysiology of dysfunctional endothelium in PAD.

Progression of atherosclerosis in patients with peripheral arterial disease as a function of angiotensin-converting enzyme gene insertion/deletion polymorphism

Angiotensin-converting enzyme insertion/deletion (I/D) gene polymorphism plays a role in determining the inter-individual variability of circulating angiotensin-converting enzyme activity and intracellular angiotensin-converting enzyme levels. Angiotensin-converting enzyme, as a key enzyme in the renin-angiotensin system, catalyzes the activation of the vasoconstricting and proliferation-stimulating angiotensin II and breaks down the vasodilatory peptide bradykinin. It is assumed that the excess supply of angiotensin II (due to the deletion polymorphism of the angiotensin-converting enzyme gene) contributes to endothelial dysfunction and in this way promotes the onset and progression of atherosclerosis. The aim of this study was to test whether the presence of the deletion allele of the angiotensin-converting enzyme gene predisposes a more rapid systemic progression of a preexisting peripheral arterial disease. To this end, the course of disease was surveyed for an average of 5 years in 97 patients who were angiotensin-converting enzyme gene-typed and suffered from a stable stage II peripheral arterial disease according to Fontaine. These patients did not suffer from an additional coronary artery disease, a cerebrovascular disease, or other serious illness. A local progression in the periphery or a systemic progression in the coronary or cerebrovascular areas was regarded as study endpoints. Of the patients, 49.5% showed an atherosclerosis progression during the surveillance period. With II-carriers, a progression was registered in 42.1% and with DD carriers, progression was seen in 59.4%. D/I allele frequencies were seen in patients with progression at a level of 0.60/0.40 vs 0.55/0.45 for patients without progression. The average duration of disease in stable stage II (before progression appeared) amounted to 108 +/- 14 months for II carriers, 88 +/- 8 months for ID carriers, and 92 +/- 11 months for DD carriers (p = 0.21). Based on these findings, the deletion polymorphism of the angiotensin-converting enzyme gene is not an independent risk factor for progression of atherosclerosis in patients with peripheral arterial disease.

Intermittent claudication: pharmacoeconomic and quality-of-life aspects of treatment

The purpose of this article is to review the literature on the pharmacoeconomics of treatment for intermittent claudication and to discuss the importance of quality-of-life assessment for evaluating treatment strategies. Systemic risk reduction is the primary objective in the treatment of patients with intermittent claudication, as these patients have a high future risk of cardiovascular morbidity and mortality. Modification of cardiovascular risk factors accompanied by antiplatelet therapy is likely to improve overall survival, reduce myocardial infarction and stroke, and will, perhaps, also reduce the risk of ulcers and amputation at acceptable cost-effectiveness ratios. The second goal in the treatment of patients with intermittent claudication is to improve their walking capacity and community-based functional status. Supervised exercise training is the most effective noninvasive intervention to improve walking capacity, but may have elevated indirect costs. Among patients with disabling claudication who are candidates for invasive therapeutic procedures, angioplasty is cost effective in those with femoropopliteal stenosis or occlusion and in those with critical limb ischaemia and a stenosis. For all these therapeutic strategies there is a need to relate the costs to a relevant and comprehensive measure of effectiveness. Quality-of-life evaluation by using questionnaires exploring the specific problems encountered by patients with intermittent claudication in their daily life appear to be the most appropriate tool to evaluate the net result of a treatment. Cost-utility studies by combining pecuniary and quality-of-life evaluations provide information that is extremely useful to patients with intermittent claudication, regulatory authorities, the pharmaceutical industry and healthcare providers.

Comparison of the effects of cilostazol and milrinone on intracellular cAMP levels and cellular function in platelets and cardiac cells

Cilostazol is a potent cyclic nucleotide phosphodiesterase (PDE) type 3 (PDE3) inhibitor that was recently approved by the Food and Drug Administration (FDA) for the treatment of intermittent claudication. Its efficacy is presumed to be due to its vasodilatory and platelet activation inhibitory activities. Compared with those treated with placebo, patients treated with cilostazol showed a minimal increase in cardiac adverse events. Because of its PDE3 inhibitory activity, however, the possibility that cilostazol exerts positive cardiac inotropic effects is a safety concern. Therefore we compared the effects of cilostazol with those of milrinone, a selective PDE3 inhibitor, on intracellular cyclic adenosine monophosphate (cAMP) levels in platelets, cardiac ventricular myocytes, and coronary smooth muscle cells. We also compared the corresponding functional changes in these cells. Cilostazol and milrinone both caused a concentration-dependent increase in the cAMP level in rabbit and human platelets with similar potency. Furthermore, cilostazol and milrinone were equally effective in inhibiting human platelet aggregation with a median inhibitory concentration (IC50) of 0.9 and 2 microM, respectively. In rabbit ventricular myocytes, however, cilostazol elevated cAMP levels to a significantly lesser extent (p < 0.05 vs. milrinone). By using isolated rabbit hearts with a Langendorff preparation, we showed that milrinone is a very potent cardiotonic agent; it concentration-dependently increased left ventricular developed pressure (LVDP) and contractility. Cilostazol was less effective in increasing LVDP and contractility (p < 0.05 vs. milrinone), which is consistent with the cardiac cAMP levels. The cardiac effect of OPC-13015, a metabolite of cilostazol with about sevenfold higher PDE3 inhibition, was similar to cilostazol. Whereas milrinone concentration-dependently increased cAMP in rabbit coronary smooth muscle cells, cilostazol did not have such an effect. However, both compounds increased coronary flow equally in rabbit hearts. Our results show that although cilostazol and milrinone both inhibit PDE3, cilostazol preferentially acts on vascular elements (platelets and flow). This unique profile of cilostazol is consistent with its beneficial and safe clinical outcomes in patients with intermittent claudication.