Cholesterol in peripheral vascular disease--a suitable case for treatment?

Aspirin nonsensitivity in patients with vascular disease: Assessment by light transmission aggregometry (aspirin nonsensitivity in vascular patients)

BACKGROUND

Aspirin is a key antiplatelet therapy for the prevention of thrombotic events in patients with cardiovascular disease. Studies suggest that ≈20% of patients with cardiac disease suffer from aspirin nonsensitivity, a phenomenon characterized by the inability of 81 mg aspirin to inhibit platelet aggregation and/or prevent adverse cardiovascular events.

OBJECTIVES

To investigate aspirin nonsensitivity in patients with vascular disease and assess the consequences of aspirin nonsensitivity.

METHODS

One hundred fifty patients presenting to St. Michael's Hospital's outpatient clinics with evidence of vascular disease (peripheral arterial disease or carotid artery stenosis) and a previous prescription of 81 mg of aspirin were recruited in this study. Light transmission aggregometry with arachidonic acid induction was used to determine sensitivity to aspirin. Patients with a maximum aggregation ≥20% in response to arachidonic acid were considered aspirin nonsensitive, as per previous studies.

RESULTS

Of the 150 patients recruited, 36 patients (24%) were nonsensitive to 81 mg of aspirin. Of these 36 nonsensitive patients, 30 patients provided a urine sample for urine salicyluric acid analysis (a major metabolite of aspirin). Urine analysis demonstrated that 14 patients were compliant and 16 were noncompliant with their aspirin therapy. Major adverse cardiovascular events and major adverse limb events were significantly higher in the nonsensitive patients compared to sensitive patients (hazard ratio, 3.68; P < 0.001).

CONCLUSION

These data highlight the high prevalence of aspirin nonsensitivity and noncompliance in patients with vascular disease and emphasizes the urgent need for improved medical management options for this patient population.

Elevated plasma levels of NT-proBNP in ambulatory patients with peripheral arterial disease

N-terminal pro B-type natriuretic peptide (NT-proBNP), a cardiac disease biomarker, has been demonstrated to be a strong independent predictor of cardiovascular events in patients without heart failure. Patients with peripheral arterial disease (PAD) are at high risk of cardiovascular events and death. In this study, we investigated levels of NT-proBNP in patients with PAD compared to non-PAD controls. A total of 355 patients were recruited from outpatient clinics at a tertiary care hospital network. Plasma NT-proBNP levels were quantified using protein multiplex. There were 279 patients with both clinical and diagnostic features of PAD and 76 control patients without PAD (non-PAD cohort). Compared with non-PAD patients, median (IQR) NT-proBNP levels in PAD patients were significantly higher (225 ng/L (120-363) vs 285 ng/L (188-425), p- value = 0.001, respectively). Regression analysis demonstrated that NT-proBNP remained significantly higher in patients with PAD relative to non-PAD despite adjusting for age, sex, hypercholesterolemia, smoking and hypertension [odds ratio = 1.28 (1.07-1.54), p-value <0.05]. Subgroup analysis showed elevated NT-proBNP levels in patients with PAD regardless of prior history of CHF, CAD, diabetes and hypercholesteremia (p-value <0.05). Finally, spearmen's correlation analysis demonstrated a negative correlation between NT-proBNP and ABI (ρ = -0.242; p-value < 0.001). In conclusion, our data shows that patients with PAD in an ambulatory care setting have elevated levels of NT-proBNP compared to non-PAD patients in the absence of cardiac symptoms.

Current therapies and investigational drugs for peripheral arterial disease

Peripheral artery disease (PAD) is associated with elevated morbidity and mortality with cardiovascular (CV) disease. The guideline recommends smoking cessation and antiplatelet/antithrombotic drugs for asymptomatic and symptomatic PAD patients. It also recommends that PAD patients with critical limb ischemia (CLI) should be considered to receive endovascular and open surgical treatment for limb salvage. Although PAD patients with CLI receive these treatments, they are sometimes unable to deliver sufficient blood flow to eliminate their symptoms. Thus specific strategies are needed to promote enough blood flow. To establish the effective method, many investigations have been performed using cell-based therapy. Endothelial progenitor cells, mononuclear cells and mesenchymal stem cells have been well investigated in clinical settings. To induce angiogenesis, vascular endothelial growth factor, fibroblast growth factor and hepatocyte growth factor (HGF) have also been transfected in PAD patients. Among them, HGF is the most promising factor because it can induce angiogenesis without the induction of vascular inflammation and increased permeability. In this review article, we summarize current treatments and investigational drugs of PAD.

Reliability of Doppler and stethoscope methods of determining systolic blood pressures: considerations for calculating an ankle-brachial index

PURPOSE

The purposes of this study were to: (1) identify the interrater and intrarater reliability of systolic blood pressures using a stethoscope and Doppler to determine an ankle-brachial index (ABI), and (2) to determine the correlation between the 2 methods.

BACKGROUND

Peripheral arterial disease (PAD) affects approximately 8 to 12 million people in the United States, and nearly half of those with this disease are asymptomatic. Early detection and prompt treatment of PAD will improve health outcomes. It is important that clinicians perform tests that determine the presence of PAD.

METHOD

Two individual raters trained in ABI procedure measured the systolic blood pressures of 20 individuals' upper and lower extremities. Standard ABI measurement protocols were observed. Raters individually recorded the systolic blood pressures of each extremity using a stethoscope and a Doppler, for a total of 640 independent measures.

RESULTS

Interrater reliability of Doppler measurements to determine SBP at the ankle was very strong (intraclass correlation coefficient [ICC], 0.93-0.99) compared to moderate to strong reliability using a stethoscope (ICC, 0.64-0.87). Agreement between the 2 devices to determine SBP was moderate to very weak (ICC, 0.13-0.61). Comparisons of the use of Doppler and stethoscope to determine ABI showed weak to very weak intrarater correlation (ICC, 0.17-0.35). Linear regression analysis of the 2 methods to determine ABI showed positive but weak to very weak correlations (r2 = .013, P = .184).

CONCLUSIONS

A Doppler ultrasound is recommended over a stethoscope for accuracy in systolic pressure readings for ABI measurements.

Peripheral arterial disease and cognitive function

As a marker of generalized atherosclerosis, peripheral arterial disease (PAD) has implications not only for the affected lower extremity but also to overall cardiovascular health. It confers an increased risk of non-fatal and fatal vascular events which increases with the severity of the disease. Patient-based studies have shown that individuals with advanced PAD tend to perform poorly on cognitive tests compared to controls. In population studies, PAD is associated with an increased cognitive decline independently of previous cerebrovascular disease and cardiovascular risk factors. A low ankle-brachial index (ABI) may be an early predictor of cognitive decline and of potential value in identifying individuals at increased risk of cognitive impairment. In patients with PAD, secondary preventive measures directed at decreasing the long-term systemic vascular complications may also be important to the preservation of cognitive health. However, evidence suggests that PAD patients may be undertreated with regard to atherosclerotic risk factors, as demonstrated by an undue emphasis on symptom relief rather than essential risk factor reduction. More research needs to be carried out to determine the predictors of cognitive function in PAD patients, whether subtle cognitive disturbances are related to activities of daily living, including medical treatment compliance, and whether neuroprotective strategies and atherosclerotic risk factor control positively influence cognitive function in these high-risk patients.

The Unsung Perils of Peripheral Arterial Disease: A Malady in Search of a Patient

Peripheral arterial disease (PAD) is increasingly recognized as a strong predictor of mortality and morbidity from atherosclerotic events, especially from coronary heart disease. Since vascular disease remains the most common cause of death in the world, the substantial prevalence, ease of diagnosis, and ominous prognosis have increased interest in PAD among the prevention community. The association with coronary heart disease is strong enough that for prevention purposes, PAD should be considered a high-risk condition that demands aggressive therapy to reduce incident vascular events. Unlike other forms of atherosclerotic disease, PAD is easily diagnosed in the outpatient clinic noninvasively, using the ankle brachial index. Because its diagnosis can thus be seamlessly integrated into the routine clinical encounter, the ankle brachial index has emerged as a tool for global risk assessment. This article will review the relationship between PAD and other vascular disease, emphasizing the role of PAD in prevention efforts.

Statins and Peripheral Arterial Disease: Potential Mechanisms and Clinical Benefits

Peripheral arterial disease (PAD) is a manifestation of widespread atherosclerosis. Lipid modification (especially with statins) is a component of the treatment of patients with PAD since this condition is considered a coronary heart disease equivalent. This review considers the mechanism of action of statins in PAD. Statins have been shown to reduce the incidence of new coronary events in patients with PAD. However, surveys suggest that many such patients remain undertreated. Statins can also increase walking distance in patients with PAD. There is also evidence that statins can improve renal function in these patients. Several other actions of statins are considered in this review. PAD patients have an increased morbidity and mortality, largely due to myocardial infarction and stroke. Recognizing and treating these high-risk patients as early as possible should be a priority.

Effect of a clinical pharmacy service on lipid control in patients with peripheral arterial disease

OBJECTIVE

Our group and others have previously established that patients with peripheral artery disease (PAD) are significantly undertreated with respect to overall cardiovascular risk factor management, despite national guidelines to the contrary. In an effort to maximize risk factor control in our patients with PAD, we established a pharmacist-managed, physician-monitored algorithmic approach to the outpatient management of lipids in patients with PAD. The purpose of this study was to determine the effect of this service on lipid screening and control in patients with PAD.

METHODS

We analyzed the records of patients treated at a large, group-model, not-for-profit regional managed care system serving approximately 405,000 members. An electronic medical record provided full examination, laboratory, and pharmacy data for all patients. Pharmacy data were analyzed to determine prescriptions for lipid-lowering agents. Lipid control was assessed through fasting lipid data. Patients with validated PAD and the absence of clinical coronary artery disease (CAD) were offered the service between May 2003 and September 2004 and followed up for a minimum of 6 months.

RESULTS

We administratively identified 5159 active patients with a diagnosis of PAD. Of these, 1075 could be validated with a noninvasive arterial study. The exclusion of 384 patients with a diagnosis of CAD resulted in a cohort of 691 patients. Of these, 90 patients were enrolled in the lipid service (study group), and 601 received standard care. Mean follow-up was 17.1 months. Screening fasting lipid profiles were found in 95.6% (86/90) of patients in the study group and only 66.9% (402/601) of the standard care patients (P < .0001). Low-density lipoprotein cholesterol (LDL-C) control was improved in the pharmacist-managed group, with 79.1% (68/86) achieving an LDL-C of less than 100 mg/dL in comparison to the standard care group (54.8% [219/400]; P < .0001). An LDL-C value of more than 130 mg/dL was noted in 1.2% and 14.0% (56/400) in the treatment and control groups, respectively (P < .001). Statin use was present in 51.9% (312/601) of the control group patients and 84.4% (76/90) of the pharmacist-managed group (P < .001).

CONCLUSIONS

Despite national consensus of PAD as a CAD equivalent, patients are currently undertreated with regard to atherosclerotic risk factor modification. Initiation of a pharmacist-managed, physician-monitored lipid service provides improved compliance with national guidelines.

Incidence of and factors associated with achieving target lipid levels in patients with peripheral arterial disease

BACKGROUND

Patients with peripheral arterial disease (PAD) have increased mortality compared with patients without PAD. Coronary artery disease (CAD) accounts for almost 75% of deaths in PAD patients. Studies suggest that PAD is underdiagnosed and atherosclerotic risk factors undertreated when compared with CAD.

OBJECTIVE

To determine whether cholesterol guidelines are being met in patients with PAD and to determine whether any independent factors increase the likelihood of reaching goal low-density lipoprotein (LDL).

DESIGN

A retrospective chart review of subjects diagnosed with PAD in 2001 at 2 Veterans Affairs Medical Centers.

MEASUREMENTS

Univariate analysis compares baseline characteristics between those reaching goal and those who do not. Multivariate logistic regression analysis identified predictors of meeting LDL goal among PAD patients.

RESULTS

Of 315 patients, 62% reached goal LDL. Those more likely to reach goal were older, had hypertension, and a history of CAD and stroke. Positive predictors of LDL goal were age and CAD, while smoking was a negative predictor.

CONCLUSION

The majority of veterans with PAD received lipid-lowering medication and achieve goal LDL, but they are more likely to do so if they are older than 70 and have a history of CAD.

CJ, Presti C, Silva ESD, De Luccia N. Doença arterial obstrutiva periférica: que atenção temos dispensado à abordagem clínica dos pacientes?

OBJETIVO: Avaliar como pacientes com doença arterial obstrutiva periférica têm sido tratados, em nosso meio, com relação aos fatores de risco e comorbidades. MÉTODO: Questionário sobre pesquisa e tratamento da dislipidemia, diabetes, exercício, uso de anti-plaquetários, tabagismo e hipertensão arterial no paciente com doença arterial obstrutiva periférica foi aplicado entre os médicos presentes na reunião mensal de março de 2004 da Sociedade Brasileira de Angiologia e Cirurgia Vascular - Regional São Paulo. RESULTADOS: Dos 102 questionários distribuídos, 75 foram respondidos (taxa de resposta de 73,5%). Entre os consultados, 82% pesquisam rotineiramente perfil lipídico e 20% visam alvo de LDL-colesterol abaixo de 100 mg/dl; 94% realizam pesquisa para diabetes melito; 97% recomendam exercício; 79% prescrevem aspirina; 97% aconselham que os pacientes parem de fumar e 60% se restringem ao aconselhamento isoladamente; 18% não realizam a medida da pressão arterial durante a consulta e 19% visam alvo pressórico de 130 x 80 mmHg. Considerando todas as avaliações em conjunto - intervenção no estilo de vida, no sentido de parar de fumar, orientação de exercícios, uso de anti-plaquetários, realização de pesquisa para diabetes melito, controle rigoroso da pressão arterial e lípides - observou-se que 7% dos entrevistados seguem todas essas recomendações como uma rotina estabelecida. CONCLUSÃO: O presente estudo demonstrou que, em nosso meio, a pesquisa e o tratamento dos fatores de risco e comorbidades nos pacientes com doença arterial obstrutiva periférica estão sendo sub-realizados.

Lipid-lowering therapy in patients with peripheral arterial disease: are guidelines being met?

OBJECTIVES

To determine the proportion of patients with lower extremity peripheral arterial disease (PAD) who reach recommended low-density lipoprotein cholesterol (LDL-C) levels (<100 mg/dL) and to identify the patient characteristics that are independently associated with attaining the LDL-C goal (<100 mg/dL).

PATIENTS AND METHODS

Eligible patients were identified from a roster of patients who had undergone testing at a nonvascular laboratory between September 1, 2001, and January 31, 2002, and were found to have evidence of PAD, defined as an ankle-brachial index of 0.9 or less. We thoroughly reviewed patients' electronic medical records. Backward elimination multivariate logistic regression modeling was used to Identify factors associated with reaching the goal LDL-C level.

RESULTS

Among 143 patients with PAD, 105 (73%) met the goal LDL-C level. Lipid-lowering therapy was prescribed for 109 (76%). Lower diastolic blood pressure and lower weight were independently associated with an LDL-C level of less than 100 mg/dL.

CONCLUSION

We found higher rates of lipid-lowering therapy in patients with PAD than reported previously. Patients with diabetes mellitus or coronary artery disease were not more likely to meet the goal LDL-C level than those without these comorbidities. Clinical practice may be catching up to clinical guidelines.

Undertreatment of dyslipidemia in peripheral arterial disease and other high-risk populations: an opportunity for cardiovascular disease reduction

Atherosclerosis is a form of arterial disease that manifests in the coronary circulation as coronary artery disease (CAD), in the carotid arteries as cerebrovascular disease, and in the aorta and lower extremity arteries as peripheral arterial disease (PAD). The systemic nature of the disease is reflected in the fact that individuals with PAD or carotid artery disease are more likely to have CAD than those without. Since individuals with PAD are at markedly increased risk of cardiovascular ischemic events, early identification of this population and more aggressive medical interventions could substantially improve both morbidity and survival. The incidence of PAD in the general population is high, and currently affects 8-10 million Americans. The risk of developing PAD is predicted by both age and common atherosclerosis risk factors (e.g., smoking and diabetes). Efficient office-based PAD detection depends on the application of objective techniques to establish this diagnosis. Objective noninvasive tests, such as measurement of the ankle-brachial index (ABI), are known to be more sensitive than traditional clinical assessments. Since the major threat to patients with PAD is from secondary cardiovascular ischemic events, a primary therapeutic goal is to modify atherosclerotic risk factors. While national recommendations mandate aggressive lowering of serum low-density lipoprotein cholesterol (LDL-C) levels as a primary treatment goal in all patients with overt atherosclerosis, as 'coronary heart disease risk equivalent' syndromes, individuals with PAD are less intensively treated than those with CAD. Statins are the most effective of current treatments in lowering LDL-C, and have proven efficacy in secondary prevention among patients with established CAD. The use of statin medications in high-risk groups such as PAD patients could prove particularly beneficial in reducing cardiovascular morbidity and mortality and therefore merits prospective clinical investigation.

Androgens and cardiovascular disease

Globally, cardiovascular disease will continue causing most human deaths for the foreseeable future. The consistent gender gap in life span of approximately 5.6 yr in all advanced economies must derive from gender differences in age-specific cardiovascular death rates, which rise steeply in parallel for both genders but 5-10 yr earlier in men. The lack of inflection point at modal age of menopause, contrasting with unequivocally estrogen-dependent biological markers like breast cancer or bone density, makes estrogen protection of premenopausal women an unlikely explanation. Limited human data suggest that testosterone exposure does not shorten life span in either gender, and oral estrogen treatment increases risk of cardiovascular death in men as it does in women. Alternatively, androgen exposure in early life (perinatal androgen imprinting) may predispose males to earlier onset of atherosclerosis. Following the recent reevaluation of the estrogen-protection orthodoxy, empirical research has flourished into the role of androgens in the progression of cardiovascular disease, highlighting the need to better understand androgen receptor (AR) coregulators, nongenomic androgen effects, tissue-specific metabolic activation of androgens, and androgen sensitivity. Novel therapeutic targets may arise from understanding how androgens enhance early plaque formation and cause vasodilatation via nongenomic androgen effects on vascular smooth muscle, and how tissue-specific variations in androgen effects are modulated by AR coregulators as well as metabolic activation of testosterone to amplify (via 5alpha-reductase to form dihydrotestosterone acting on AR) or diversify (via aromatization to estradiol acting upon estrogen receptor alpha/beta) the biological effects of testosterone on the vasculature. Observational studies show that blood testosterone concentrations are consistently lower among men with cardiovascular disease, suggesting a possible preventive role for testosterone therapy, which requires critical evaluation by further prospective studies. Short-term interventional studies show that testosterone produces a modest but consistent improvement in cardiac ischemia over placebo, comparable to the effects of existing antianginal drugs. By contrast, testosterone therapy has no beneficial effects in peripheral arterial disease but has not been evaluated in cerebrovascular disease. Erectile dysfunction is most frequently caused by pelvic arterial insufficiency due to atherosclerosis, and its sentinel relationship to generalized atherosclerosis is insufficiently appreciated. The commonality of risk factor patterns and mechanisms (including endothelial dysfunction) suggests that the efficacy of antiatherogenic therapy is an important challenge with the potential to enhance men's motivation for prevention and treatment of cardiovascular diseases.

Atherosclerotic risk factor reduction in peripheral arterial diseasea: results of a national physician survey

OBJECTIVE

Individuals with peripheral arterial disease (PAD) have a 3- to 6-fold increased risk of coronary heart disease and stroke compared to those without PAD. We documented physician-reported practice behavior, knowledge, and attitudes regarding atherosclerotic risk factor reduction in patients with PAD.

DESIGN

National physician survey.

PATIENTS/PARTICIPANTS

General internists (N = 406), family practitioners (N = 435), cardiologists (N = 473), and vascular surgeons (N = 264) randomly identified using the American Medical Association's physician database.

MEASUREMENTS AND MAIN RESULTS

Physicians were randomized to 1 of 3 questionnaires describing a) a 55- to 65-year-old patient with PAD; b) a 55- to 65-year-old patient with coronary artery disease (CAD), or c) a 55- to 65-year-old patient without clinically evident atherosclerosis (no disease). A mailed questionnaire was used to compare physician behavior, knowledge, and attitude regarding risk factor reduction for each patient. Rates of prescribed antiplatelet therapy were significantly lower for the patient with PAD than for the patient with CAD. Average low-density lipoprotein levels at which physicians "almost always" initiated lipid-lowering drugs were 121.6 +/- 23.5 mg/dL, 136.3 +/- 28.9 mg/dL, and 149.7 +/- 24.4 mg/dL for the CAD, PAD, and no-disease patients, respectively (P <.001). Physicians stated that antiplatelet therapy (P <.001) and cholesterol-lowering therapy (P <.001) were extremely important significantly more often for the CAD than for the PAD patient. Perceived importance of risk factor interventions was highly correlated with practice behavior. Compared to other specialties, cardiologists had lowest thresholds, whereas vascular surgeons had the highest thresholds for initiating cholesterol-lowering interventions for the patient with PAD. Cardiologists were significantly more likely to report "almost always" prescribing antiplatelet therapy for the patient with PAD than were all other physicians.

CONCLUSIONS

Deficiencies in physician knowledge and attitudes contribute to lower rates of atherosclerotic risk factor reduction for patients with PAD. Reversing these deficiencies may reduce the high rates of cardiovascular morbidity and mortality associated with PAD.

Second best medical therapy

BACKGROUND

Best medical therapy (BMT) provides patients with peripheral arterial disease (PAD) substantial protection against future vascular events.

OBJECTIVE

To determine the quality of BMT received by PAD patients in this vascular surgery unit.

METHODS

Retrospective case-note review of 50 consecutive patients in each of the following groups: intermittent claudication (out-patients), symptomatic carotid artery disease (out-patients), lower limb angioplasty, lower limb bypass surgery, carotid endarterectomy.

RESULTS

Overall BMT use was poor. Fifteen percent of smokers had assistance with smoking cessation noted. Seventy-eight percent of patients were taking an antiplatelet agent, 38% cholesterol-lowering medication and 51% antihypertensive medication. Fifty-three percent of patients had a cholesterol measurement, 50% of out-patients had a blood pressure measurement and 53% of non-diabetics had a random blood glucose performed. Sixteen of the patients with lower limb disease were given advice about exercise. Patients with a history of coronary artery disease were more likely to be taking cholesterol lowering, or antihypertensive medication.

CONCLUSIONS

BMT is poorly used in patients with PAD, which will result in an excess of cardiovascular morbidity and mortality. Strategies need to be developed to increase the use of BMT in our patients.

What constitutes best medical therapy for peripheral arterial disease?

Peripheral arterial disease (PAD) is associated with a high morbidity and mortality, largely from coronary and cerebrovascular disease, which often overshadows the PAD itself. Best Medical Therapy (BMT), comprising smoking cessation, antiplatelet agent use, cholesterol reduction, exercise therapy, and the diagnosis and treatment of hypertension and diabetes mellitus; is evidenced based and can result in significant reductions in cardiovascular risk, as well as some improvement in PAD. Previous data have largely been restricted to patients with coronary artery disease, and their relevance to PAD has been extrapolated. However, data are now starting to become available, such as the Heart Protection Study, with data specific to PAD patients. This article reviews the data regarding the use of BMT in patients with PAD, and based on this, makes recommendations for the use of BMT in this group of patients.

The lack of cardiovascular risk factor management in patients with critical limb ischaemia

AIM

to define the level of management of cardiovascular risk factors in patients treated for critical limb ischaemia in a vascular surgical setting.

MATERIALS AND METHODS

retrospective review of all (n =147) patients operated on for critical lower extremity ischaemia in 1998. We included pre- and postoperative cardiac events.

RESULTS

only eight (5%) (95% CI; 2-9) were on lipid lowering treatment and 58 (39%) (95% CI; 31-47) using acetylsalicylic acid.

CONCLUSIONS

only a minority of patients operated on for CLI were receiving adequate cardiovascular risk factor modification.

Nutritional and medical therapy for dyslipidemia in patients with cardiovascular disease

Dyslipidemia is a significant risk factor for the progression of cardiovascular disease, particularly when associated with other risk factors. An understanding of the pathophysiology and risks for patients with atherosclerotic diseases of undertreated dyslipidemia is essential for the healthcare provider. In this article, a review of epidemiologic data regarding the role of lipid levels in cardiovascular disease prognosis is presented. A familiarity with current dietary and drug treatment of lipid disorders is at the core of an evidence-based approach to dyslipidemia management in the patient with established cardiovascular diseases.