Risk Modification in Patients with Peripheral Arterial Disease: A Retrospective Survey

Utilization of Vasculoprotective Therapy for Peripheral Artery Disease: A Systematic Review and Meta-analysis

INTRODUCTION

Practice guidelines recommend that patients with peripheral artery disease receive antiplatelets, statins, and angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). We sought to quantify the rates of prescribing these therapies in patients with peripheral artery disease in the literature.

METHODS

We performed a systematic review and meta-analysis of treatment prescribing rates in observational studies containing peripheral artery disease patients published on or after the year 2000. We also assessed whether prescribing rates are increasing over time.

RESULTS

A total of 86 studies were available for analysis. The aggregate sample size across all studies was 332,555. The pooled estimates for utilization of antiplatelets, statins, and ACE inhibitors or ARBs were 75% (95% confidence interval [CI], 71%-79%), 56% (95% CI, 52%-60%), and 53% (95% CI, 49%-58%), respectively. Statin use was directly related to publication year (+2.0% per year, P < .001), but this was not the case for antiplatelets (P = .68) or ACE inhibitors or ARBs (P = .066).

CONCLUSIONS

Although some improvement in statin prescribing has occurred in recent years, major practice gaps exist in the treatment of peripheral artery disease. Effective measures to close these gaps should be implemented.

The anti-microbial peptide SR-0379 stimulates human endothelial progenitor cell-mediated repair of peripheral artery diseases

Ischemia is a serious disease, characterized by an inadequate blood supply to an organ or part of the body. In the present study, we evaluated the effects of the anti-microbial peptide SR-0379 on the stem cell-mediated therapy of ischemic diseases. The migratory and tube-forming abilities of human endothelial progenitor cells (EPCs) were enhanced by treatment with SR-0379 in vitro. Intramuscular administration of SR-0379 into a murine ischemic hindlimb significantly enhanced blood perfusion, decreased tissue necrosis, and increased the number of blood vessels in the ischemic muscle. Moreover, co-administration of SR-0379 with EPCs stimulated blood perfusion in an ischemic hindlimb more than intramuscular injection with either SR-0379 or EPCs alone. This enhanced blood perfusion was accompanied by a significant increase in the number of CD31- and α-SMApositive blood vessels in ischemic hindlimb. These results suggest that SR-0379 is a potential drug candidate for potentiating EPC-mediated therapy of ischemic diseases. [BMB Reports 2017; 50(10): 504-509].

Short-term Lipid-Lowering Treatment with Atorvastatin Improves Renal Function But Not Renal Blood Flow Indices in Patients with Peripheral Arterial Disease

Some studies have suggested that lipid lowering with statins exerts favorable effects on the progression of chronic kidney disease. Therefore, the authors assessed the effects of short-term atorvastatin treatment on biochemical markers of renal function and evaluated duplex indices of renal blood flow (RBF) in patients with peripheral arterial disease. Hyperlipidemic claudicants (n=18), aged 44-85 years, were treated for 8 weeks with 20 mg/day atorvastatin. Blood tests at baseline and after 8 weeks included serum fasting lipids, creatinine, urate, and cystatin C (a sensitive indicator of renal function) levels. RBF was also assessed (n=9) by measuring pulsatile and resistance duplex indices. As expected, there was a significant improvement in total cholesterol, low-density lipoprotein cholesterol, and triglycerides. There was also a significant (p<0.0001) fall in serum creatinine from 89 (58-125) to 79 µmol/L (54-119) and an increase in calculated creatinine clearance (CrCl) from 72 (40-129) to 80 mL/minute (47-138; p<0.0001). Serum cystatin C values decreased significantly (p=0.0002) from 1.04 (0.57-1.56) to 0.90 mg/L (0.47-1.47). There were no detectable changes in the RBF duplex indices. Treatment of stable claudicants with atorvastatin for 8 weeks was associated with improved renal function (as assessed by serum creatinine, cystatin C, and calculated CrCl) without changes in RBF. Further studies are required to identify the mechanisms involved in this phenomenon.

Low estimated glomerular filtration rate is a major determinant of low ankle-brachial index and toe-brachial index in type 2 diabetes

We enrolled 1461 Taiwanese type 2 diabetic outpatients with ankle-brachial index (ABI) and toe-brachial index (TBI) examinations, excluding participants with history of stroke, end-stage renal disease, malignancy, acute myocardial infarction, amputation, and overt calcification of the lower limbs (ABI > 1.3). Ankle-brachial index values <0.9 were found in 2.8% of the patients and 5.7% had TBI < 0.6. Estimated glomerular filtration rate (eGFR; 90 ± 33 mL/min per 1.73 m2) obtained from 473 patients correlated significantly with both ABI and TBI. Progressive eGFR decline was observed in 419 participants with normal ABI and TBI, 35 with normal ABI but low TBI, and 19 with low ABI and normal or low TBI (P for trend < .001). After adjusting for confounding factors, age and eGFR were significantly associated with TBI and ABI. Low eGFR is associated with peripheral arterial disease in type 2 diabetes with mild to moderate renal insufficiency.

A prospective randomized controlled study with intermittent mechanical compression of the calf in patients with claudication

OBJECTIVES

The study tested the feasibility of using a new portable mechanical compression device for the treatment of claudication. The device applies intermittent non-pneumatic mechanical compression (IMC) to the calf. It was hypothesized that it can offer a low-cost convenient option for patients and achieve good compliance and improved clinical outcomes.

METHODS

Thirty patients were enrolled in a randomized controlled single blind study. Fourteen patients were assigned to active IMC. Sixteen control patients continued with medical treatment alone. Outcomes were recorded at baseline, after one month, three months, and six months. The study examined changes in exercise tolerance using Initial Claudiacation Distance (ICD) and Absolute Claudiaction Distance (ACD) as well as ankle-brachial index at rest (ABI-r) and post-exercise (ABI-pe). All patients had stable claudication due to peripheral arterial disease (PAD) and were already under best medical treatment (BMT). To be eligible for inclusion, patients had to be between the ages of 50 and 75 years, had to have stable claudication with an absolute claudication distance >40 meters but <300 meters on a standardized treadmill stress test (3.8 km/h at a 10% grade), have a resting ABI in the affected limb <0.8 with a drop of at least 0.15 following exercise, in whom surgical intervention was not expected for at least three months. Fourteen patients were assigned to active IMC consisting of compressions 65 mm Hg in amplitude, applied for three 3-second compressions/minute, two hours/day for three months. Sixteen control patients continued with BMT alone.

RESULTS

One month after treatment, ICD increased by 66% (P = .001), ACD increased by 51.75% (P = .005), and ABI-pe increased by 42% (P = .01). Treatment effects were maintained or further improved after three months. ABI-r did not increase at any time. Compliance exceeded 80%. Three months following cessation of therapy, claudication distances and ABI-pe did not decrease significantly.

CONCLUSIONS

We concluded that the use of IMC of the calf for three months increased claudication distances and led to objective improvements in ABI-pe. Intermittent mechanical compression may be a useful approach to patients with continued claudication despite standard medical treatment.

Diagnosis and treatment of dyslipidemia are neglected in patients with peripheral artery disease

OBJECTIVE

Our aim was to investigate how dyslipidemia was diagnosed and treated in patients with peripheral artery disease (PAD) in a university vascular clinic.

DESIGN

Our analysis included all 1 843 PAD patients (median age 71 years, interquartile range 63-79, M/W 975/868) who attended the clinic in 2002-2003 either for diagnostic angiography or for revascularization. The charts of patients tested for dyslipidemia were reviewed closer.

RESULTS

Serum lipids were measured in only 214 PAD patients (11.6%). Of them 37.9% smoked, 59.8% had antihypertensive medication, 35.0% diabetes, and 30.8% a history of coronary heart disease. Mean serum cholesterol concentration was 4.5 mmol/l (SD 1.3), LDL-cholesterol 2.54 (0.48), HDL-cholesterol 1.25 (0.48), and triglycerides 1.62 (0.84). Only 40 patients (19.7%) were using statins, this was increased to 72 (33.6%) after clinic visit. Consequently, 50.0% and 53.2% met the current total cholesterol (<4.5 mmol/l) and LDL-cholesterol (<2.5 mmol/l) goals, respectively.

CONCLUSIONS

Dyslipidemia was highly under-diagnosed among PAD patients. Serum lipids were measured only in a minority and among them serum lipid values and the use of hypolipidemic drugs were not optimal according to guidelines.

Kidney function and estimated vascular risk in patients with primary dyslipidemia

Background:

Chronic kidney disease (CKD) is associated with increased vascular risk. Some studies suggested that considering markers of CKD might improve the predictive accuracy of the Framingham risk equation.

Aim:

To evaluate the links between kidney function and risk stratification in patients with primary dyslipidemia.

Methods:

Dyslipidemic patients (n = 156; 83 men) who were non-smokers, did not have diabetes mellitus or evident vascular disease and were not on lipid-lowering or antihypertensive agents were recruited. Creatinine clearance (CrCl) was estimated using the Cockcroft-Gault equation. Estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease (MDRD) equation. We estimated vascular risk using the Framingham equation.

Results:

In both men and women, there was a significant negative correlation between estimated Framingham risk and both eGFR and CrCl (p < 0.001 for all correlations). When men were divided according to creatinine tertiles, there were no significant differences in any parameter between groups. When men were divided according to either eGFR or CrCl tertiles, all estimated Framingham risks significantly increased as renal function declined (p<0.001 for all trends). When women were divided according to creatinine tertiles, all estimated Framingham risks except for stroke significantly increased as creatinine levels increased. When women were divided according to either eGFR or CrCl tertiles, all estimated Framingham risks significantly increased as renal function declined.

Conclusions:

Estimated vascular risk increases as renal function declines. The possibility that incorporating kidney function in the Framingham equation will improve risk stratification requires further evaluation.

Effect of acute cigarette smoking on left and right ventricle filling parameters: a conventional and tissue Doppler echocardiographic study in healthy participants

Acute effects of smoking on left and right ventricular function is determined by conventional and tissue Doppler imaging methods in this study. Pulsed-wave Doppler indices of the left and right ventricle diastolic function, including mitral and tricuspid inflow peak early and late velocity and their ratio were obtained from 20 healthy subjects by conventional Doppler and tissue Doppler imaging. Echocardiographic indices of left and right ventricles, including isovolumetric relaxation time, deceleration time, isovolumetric contraction time, ejection time, and myocardial performance index of right ventricle were measured before and 30 minutes after smoking a cigarette. Mitral and tricuspid inflow parameters and right ventricular myocardial performance index significantly altered after smoking a cigarette. Among the tissue Doppler imaging parameters, mitral and tricuspid lateral annulus diastolic, but not systolic, velocities altered after smoking a cigarette. Acute cigarette smoking alters left and right ventricular diastolic functions in healthy nonsmokers.

Lipid abnormalities and cardiovascular risk in the elderly

The relationship between dyslipidaemia and cardiovascular disease is well documented. However, it is relevant to consider that cholesterol levels vary with age. Moreover, there is some controversy regarding the ability of lipid levels to predict vascular risk beyond the age of 70 years. In general, raised low-density lipoprotein cholesterol (LDL-C) and triglyceride levels as well as reduced levels of high-density lipoprotein cholesterol (HDL-C) predict risk in the elderly. There is evidence supporting the use of statins in the elderly. It is also likely that these drugs are under-used in this population.

[Risk status of patients with peripheral arterial disease (PAD)]

The authors have analyzed clinical and laboratory risk factors of 168 patients with PAD and 82 control persons. Among the patients the prevalences of diabetes, coronary heart disease (CHD), and cerebrovascular disease (CVD) were 30.4%, 39.9%, and 6.5%, respectively. 7.1% of the patients had CHD and CVD. Among patients with PAD and control persons, the prevalences of hypertension and current smoking were 76.2% vs 46.3% and 49.4% vs 28%. HDL-cholesterol and ApoA1 levels were significantly lower, while the triglycerides, fibrinogen, hsCRP, homocysteine, creatinine, uric acid levels, and white blood cell count as well as plasma viscosity were significantly higher in the patient group compared with the values of control persons. Among the PAD patients the diabetics and the smokers had further unfavourable significant differencies in the laboratory findings compared with the data of non-diabetics and non-smokers. Correlations were detected between the hsCRP level and the white blood cell count, the plasma viscosity and the fibrinogen level, respectively. Examining 16 selected risk factors the average risk factor count of the patients was 7.79. 118 patients had lipid-lowering, and 142 patients had antithrombotic therapy. Our results emphasize the necessity of the secondary prevention among PAD patients.

Acute effect of cigarette smoking on heart rate variability

Acute cigarette smoking enhances adrenergic activity and thus may be associated with hemodynamic changes in the cardiovascular system. In this study, the acute effect of cigarette smoking on heart rate variability (HRV) was studied. Fifteen subjects were included in the study. Time domain (the mean R-R interval, the standard deviation of R-R interval, and the root mean square of successive R-R interval differences) and frequency domain (high-frequency, low-frequency ratio, and low-frequency/high-frequency ratio) parameters of HRV were obtained from all participants for each 5-minute segment: 5 minutes before and 5, 10, 15, 20, 25, and 30 minutes after smoking a cigarette. The mean R-R interval, the standard deviation of R-R interval, and the root mean square of successive R-R interval differences significantly decreased within the first 5-minute period compared with baseline, and then the standard deviation of R-R interval increased within the 20- to 30-minute period. The low-frequency high-frequency ratio significantly decreased within the first 5 minutes after smoking and then remained unchanged throughout the study period. Similarly, low-frequency and high-frequency power increased within the first 5 minutes compared with baseline. Acute cigarette smoking alters HRV parameters, particularly within the first 5 to 10 minutes after smoking.

The role of fibrinogen and fibrinolysis in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with high rates of cerebrovascular and cardiovascular events; PAD is a marker of systemic atherosclerosis. As a result, standard therapy for all PAD patients should be directed at both peripheral and systemic atherosclerosis. Modification of established risk factors in the form of smoking cessation, correcting hypertension, optimizing diabetic control and normalizing lipids is essential. Furthermore, novel risk factors have emerged including fibrinogen and other hemostatic factors. Fibrinogen is a coagulation factor and a marker of the acute phase response (inflammation), a platelet activator, a major determinant of plasma viscosity and a component of the atherosclerotic plaque. Fibrinogen appears not only to predict the severity of PAD, but also serves as a marker for future development of PAD. Whether reducing the levels of fibrinogen and other coagulation factors will decrease the incidence and progression of PAD remains to be resolved. This review summarizes the role of fibrinogen in the pathogenesis of PAD and its association with other hemostatic factors. The role of fibrinolysis in patients with PAD is also considered.

A population-based study of peripheral arterial disease prevalence with special focus on critical limb ischemia and sex differences

OBJECTIVE

A population-based point-prevalence study was conducted to determine the prevalence of peripheral arterial disease (PAD) in Sweden, with special attention to critical limb ischemia and sex differences.

METHODS

An age-standardized randomly selected population sample of 8000 women and men, aged 60 to 90 years, from four different regions in Sweden was invited to participate. The sample had the same age and gender distribution as the Swedish population in this age group. Participating subjects completed questionnaires on medical history, present medication, and symptoms, and their ankle-brachial index (ABI) was measured. Subjects were analyzed for presence of PAD according to reported symptoms and an ABI<0.9.

RESULTS

A total of 5080 subjects were included, giving a participation rate of 64%. The prevalence of any PAD, asymptomatic PAD, intermittent claudication, and severe limb ischemia was, respectively, 18% (95% confidence interval [CI], 16% to 20%) 11% (9% to 13%), 7% (6.5 to 7%) and 1.2% (1% to 1.5%). Women had a higher prevalence than men when PAD was diagnosed with ABI only; that is, asymptomatic PAD (12.6% vs 9.4%, P=.03) and severe limb ischemia (1.5% vs 0.8%, P<.008). The prevalence of any PAD was 7.9% in the age group 60 to 65 years and increased to 47.2% among the age group 85 to 90 years. Severe limb ischemia occurred in 0.3% in the youngest age group, was highest in the age group 80 to 84 years at 3.3%, and declined to 2.5% among the oldest. The prevalence of PAD differed between regions (P<.0001).

CONCLUSIONS

PAD is common in Sweden, and almost a fifth of all elderly individuals have some stage of this disease. Women are more often afflicted than men. The prevalence of severe ischemia, as a measure of critical limb ischemia, is about 1% the population.

The role of established and emerging risk factors in peripheral vascular graft occlusion

Several studies have evaluated the association between established as well as emerging vascular risk factors with peripheral graft occlusion. There is evidence for a link between the risk for graft occlusion and total serum cholesterol, low-density lipoprotein cholesterol and triglyceride levels. The overall effect of smoking shows a 2.35-fold increase in risk of graft failure. Studies involving diabetic patients undergoing peripheral bypass may have failed to detect higher occlusion rates, possibly due to increased morbidity and mortality as well as higher amputation rates even if the graft is patent. Both antiplatelet agents and anticoagulation seem to be effective in the prevention of graft occlusion. Unconvincing data have been published with regards to the effect of hypertension on graft patency. Emerging factors such as fibrinogen, lipoprotein (a), C-reactive protein and homocysteine levels should also be considered when assessing the risk of graft occlusion. More research is needed to prevent graft occlusion due to the obvious clinical relevance, quality of life and cost issues.

p-Coumaric acid, a common dietary phenol, inhibits platelet activity in vitro and in vivo

p-Coumaric acid (3-(4-hydroxyphenyl)-2-propenoic acid; 4CA), is a ubiquitous plant metabolite with antioxidant and anti-inflammatory properties. The antiplatelet activity of this compound was analysed both ex vivo and in vitro. 4-CA, administered to rabbits for 2 weeks at the dose of 5 mg/kg, mixed with food, inhibited ADP-induced platelet aggregation without affecting blood coagulation. This effect was associated with a marked increase in plasma antioxidant activity, measured as ferric reducing ability of plasma, and with the reduction of thromboxane B2 production. The antiplatelet effect was confirmed by in vitro experiments on human blood: 4CA (500 microM and 1 mM) reduced ADP-induced platelet aggregation (55 x 2 (se 4 x 01) % and 35 x 6 (se 2 x 35) % relative to basal level, respectively). 4CA was able to modify platelet function, measured with PFA-100, a shear-inducing device that simulates primary haemostasis. 4CA interfered also with arachidonic acid cascade, reducing thromboxane B2 production and lipopolysaccharide-induced prostaglandin E2 generation (ic50 371 and 126 microM, respectively). The data show that 4CA is an antioxidant compound with good antiplatelet activity at doses that can be obtained with dietary intervention, suggesting possible applications for primary prevention of vascular disease.

Organising a Nurse-driven PAD Rehabilitation Clinic Within the Vascular Surgical Department: What is Required and are Treatment Goals Reached – A Prospective Study?

OBJECTIVES

Patients with PAD may have severe symptoms from their lower extremities as well as a 3-4 fold increased risk of death due to systemic atherosclerosis. The purpose of this study was to identify whether treatment goals of a nurse led rehabilitation clinic were achieved.

DESIGN

Prospective cohort study over 4 year period to May 2004.

METHODS

All patients with symptomatic PAD were offered enrollment in a nurse-led rehabilitation clinic and given advice on diet and exercise. All smokers were offered smoking cessation advice and treatment. Anti-platelet therapy was prescribed to all patients and statin therapy was prescribed to those with dyslipidemia.

RESULTS

693 patients with symptomatic PAD were prospectively entered into the clinic (total 2563 clinic visits). Average age was 67 years and 53% were males. Some (167, 24%) were included for non-surgical treatment and most (526, 76%) were included as part of their postoperative follow-up. After 6 months, the proportion of patients taking platelet inhibitors and statins had increased from 63% and 27% to 87% and 84% respectively. Mean total cholesterol was reduced from 6.2 mmol/l to 4.9 mmol/l and mean LDL cholesterol from 3.9 mmol/l to 2.6 mmol/l. After 1 year the proportion of smokers was reduced from 59% to 51.5% (12.5% relative reduction).

CONCLUSION

This nurse-driven rehabilitation clinic has proven effective in reaching medication targets for secondary prevention. Smoking cessation was less successful.

Smoking and Aortic Diseases

Cigarette smoking is a major vascular risk factor and in this context, it is an independent risk factor for the development of aortic disease, especially the formation and growth of abdominal aortic aneurysms (AAA). Medline was searched up to January 31, 2007 for the relevant literature for this review of the mechanisms by which smoking causes aortic wall damage and its subsequent impact on the clinical manifestation of this process. Idiopathic AAAs and aortic dissection are considered, as well as other aortic diseases (eg, Takayasu, Kawasaki, Behcet and Buerger). There is evidence suggesting an abnormal homeostasis between proteolytic and antiproteolytic activity in the vascular wall during the development of AAAs, and these mechanisms can be influenced by smoking. Smoking cessation plays an important role in the management of aortic disease.

Ezetimibe/simvastatin single tablet versus rosuvastatin in patients with hypercholesterolemia

Recent guidelines recommend strict goals for low density lipoprotein cholesterol (LDL-C) (70-100 mg/dL; 1.8-2.6 mmol/L). These goals were set following the publication of several trials. In the current issue of the journal, a study compares different doses of the combination tablet (ezetimibe/simvastatin) with statin monotherapy (rosuvastatin). In keeping with previous literature, the combination therapy was more effective in achieving LDL-C goals. This editorial comments on the potential disadvantages of using monotherapy with high-dose statins and considers the issue of statin-induced proteinuria. Combination therapy may need to be increasingly used to achieve the LDL-C targets set by recent guidelines.