Clinical significance of a high ankle-brachial index: insights from the Atherosclerosis Risk in Communities (ARIC) Study

High ankle-brachial index participants experienced similar long-term mortality as peripheral artery disease in a national sample of community-dwelling adults

BACKGROUND

Only a few small studies have shown the association between high ankle-brachial pressure index (ABI >1.4) and adverse cardiovascular (CV) events and mortality. Although there is abundant literature depicting the association between ABI and overall systemic atherosclerosis, it typically focuses on low ABI. Furthermore, historically, many studies focusing on peripheral artery disease have excluded high ABI participants. We aimed to study the mortality outcomes of persons with high ABI in the National Health and Nutrition Examination Survey (NHANES).

METHODS

We obtained ABI from participants aged ≥40 years for survey years 1999 to 2004. We defined low a ABI as ≤0.9, normal ABI as 0.9 to 1.4, and high ABI as >1.4 or if the ankle pressures were >245 mm Hg. Demographics, various comorbidities, and laboratory test results were obtained at the time of the survey interview. Multivariable adjusted hazard ratios (HRs) along with 95% confidence intervals (CIs) were calculated for CV and all-cause mortality via Cox proportional hazards regression. Mortality was linked to all NHANES participants for follow-up through December 31, 2019, by the Centers for Disease Control and Prevention.

RESULTS

We identified 7639 NHANES participants with available ABI. Of these, 6787 (89%) had a normal ABI, 646 (8%) had a low ABI, and 206 (3%) had elevated ABI. Of participants with high ABI, 50% were men, 15% were African Americans, 10% were current smokers, 56% had hypertension, 33% had diabetes, 15% had chronic kidney disease (CKD), and 18% had concomitant coronary artery disease (CAD). Diabetes (odds ratio [OR], 2.4; 95% CI, 1.7-3.2), CAD (OR, 1.6; 95% CI, 1.0-2.4), and CKD (OR, 1.5; 95% CI, 1.0-2.3) at baseline were associated with having a high ABI, respectively. A high ABI was associated independently with elevated CV (HR, 2.6; 95% CI, 2.1-3.1; P < .0001) and all-cause mortality (HR, 2.5; 95% CI, 2.2-2.8; P < .0001) after adjusting for covariates, including diabetes, CKD, CAD, current smoking, cancer, and hypertension.

CONCLUSIONS

A high ABI is associated with an elevated CV and all-cause mortality, similar to patients with PAD. High ABI participants should receive the same attention and aggressive medical therapies as patients with PAD.

Impaired brachial flow-mediated dilation may predict choroidal and retinal nerve fibre layer thickness changes in people with obesity

CLINICAL RELEVANCE

Choroidal thickness and peripapillary retinal nerve fibre layer (RNFL) changes are known to occur in obesity. Endothelial dysfunction and systemic atherosclerosis may play a role in the pathophysiology of these differences.

BACKGROUND

Flow-mediated dilation (FMD) is reduced in patients with endothelial dysfunction, and the ankle-brachial index is a surrogate marker for atherosclerosis. This study was conducted to examine the relationship between systemic vascular parameters (FMD, and ankle-brachial index), subfoveal choroidal thickness, and peripapillary RNFL thickness in obese individuals.

METHODS

This observational, cross-sectional study involved 108 total participants who were divided into two groups. One group consisted of 54 obese subjects who each had a body mass index of 30 kg/m2 or more. The other control group contained 54 participants who each had a body mass index of 25 kg/m2 or less but higher than 20 kg/m2 . For each participant, only one eye was examined in this study. Subfoveal choroidal thickness, RNFL thickness, ankle-brachial index, and ultrasound measurement of the brachial artery FMD were performed. FMD was categorised according to receiver operating characteristic analysis, and endothelial dysfunction was defined as an FMD ≤ 7.29%.

RESULTS

Subfoveal choroidal and RNFL thicknesses in the temporal quadrant were significantly lower in the obese group (p < 0.05). Lower mean values of subfoveal choroidal and RNFL thicknesses in the temporal and inferior quadrants were observed in subjects with an FMD ≤ 7.29% (p < 0.05). In people with obesity, FMD was positively correlated with subfoveal choroidal thickness (r = 0.322, p = 0.001), inferior RNFL thickness (r = 0.259, p = 0.007), and temporal RNFL thickness (r = 0.297, p = 0.002). However, the ankle-brachial index was not correlated with obesity.

CONCLUSIONS

Impaired FMD was associated with reduced subfoveal choroidal and RNFL thicknesses in the temporal and inferior quadrants of people with obesity.

Peripheral arterial disease: A small and large vessel problem

Peripheral arterial disease (PAD) is one clinical manifestation of systemic atherosclerosis and is very common. Despite its prevalence, PAD remains underdiagnosed, undertreated, and understudied. The most common symptom in patients with PAD is intermittent claudication (IC), or pain in the lower extremities with walking or exertion, which is relieved after a short period of rest. Many patients with confirmed PAD are asymptomatic or have symptoms other than IC. Regardless of symptoms, patients with PAD have poor cardiovascular outcomes. PAD has largely been viewed a disease of large vessel atherosclerosis but what is becoming clear is that arterial plaques and occlusions are only one piece of the puzzle. Recent work has shown that abnormalities in the microvasculature contribute to the outcome of patients with PAD. From the perspective of the leg, limitation in blood flow is not the only problem as patients have a myriad of other problems, including muscle fibrosis, neuropathic changes, changes in the cellular respiration machinery and dysfunction of the small vessels that perfuse skeletal muscle and the supporting structures. Supervised exercise training remains one of the most effective tool to treat patients with PAD, however, the mechanisms behind its effectiveness are still being elucidated and use of structured exercise programs is not widespread. Medical therapy to treat systemic atherosclerosis is underutilized in patients with PAD. Invasive therapies are used only when patients with PAD have reached an advanced stage. While invasive strategies are effective in some patients with PAD, these strategies are costly, carry risk, and many patients are not amenable to invasive therapy. Appreciating the complex pathophysiology of PAD will hopefully spur new research and development of effective therapies for PAD.

High ankle brachial index predicts high risk of cardiovascular events amongst people with peripheral artery disease

Ankle-brachial pressure index (ABPI) is commonly measured in people referred to vascular specialists. This study aimed to assess the association of high ABPI (≥ 1.4) with cardiovascular events in people with peripheral artery disease (PAD). 1533 participants with PAD diagnosed by a vascular specialist were prospectively recruited from four out-patient clinics in Australia. ABPI was measured at recruitment and the occurrence of myocardial infarction (MI), stroke or cardiovascular death (major cardiovascular events; MACE) and any amputation were recorded over a median (inter-quartile range) follow-up of 3.3 (1.0-7.1) years. The association of high, compared to normal, low (0.5-0.9) or very low (<0.5), ABPI with clinical events was estimated using Cox proportional hazard analyses, adjusting for traditional risk factors and reported as hazard ratio with 95% confidence intervals. 596 (38.9%), 676 (44.1%), 157 (10.2%) and 104 (6.8%) participants had normal, low, very low and high ABPI, respectively. Participants with high ABPI had increased risk of MACE, MI and death by comparison to those with either normal ABPI [1.69 (1.07, 2.65), 1.93 (1.07, 3.46) and 1.67 (1.09, 2.56)] or either low or very low ABPI [1.51 (1.02, 2.23), 1.92 (1.16, 3.19) and 1.47 (1.02, 2.14)] after adjusting for other risk factors. Findings were similar in a sensitivity analysis excluding people with ABPI only measured in one leg (n = 120). Participants with high ABPI also had an increased risk of MACE and MI compared to those with very low ABPI alone. High ABPI is a strong indicator of excess risk of cardiovascular events amongst people with PAD.

Relation between high Ankle-Brachial Index and cardiovascular outcomes in the general population and cardiovascular disease: a meta-analysis

INTRODUCTION

Conflicting findings have been reported on the association between high Ankle-Brachial Index (ABI) and cardiovascular outcomes. This meta-analysis aimed to assess the association of abnormally high ABI and cardiovascular outcomes in the general population and suspected or established cardiovascular disease (CVD) patients.

EVIDENCE ACQUISITION

A comprehensive literature search was conducted in PubMed and Embase databases through November 10th, 2018. All observational studies evaluating the association of high ABI with cardiovascular events including stroke, coronary heart disease (CHD), congestive heart failure, and composite of CVD/all-cause mortality in the general population and suspected or established CVD patients were included. We pooled risk ratios (RR) with 95% confidence intervals (CI) for the abnormally high ABI (> 1.3 or >1.4) versus the reference normal ABI category.

EVIDENCE SYNTHESIS

We identified 10 cohort studies enrolling 39,421 participants. A random effect model meta-analysis indicated that the pooled RR of composite of CVD/all-cause mortality was 1.07 (95% CI 0.83-1.38) in the general population and 1.26 (95% CI 1.03-1.55) in suspected or established CVD patients. Moreover, participants with abnormally high ABI did not increase the risk of stroke (RR 1.60; 95% CI 0.83-3.06) and CHD (RR 1.40; 95% CI 0.87-2.24) in the general population.

CONCLUSIONS

Abnormally high ABI appears to be associated with an increased risk of a composite of CVD/all-cause mortality in suspected or established CVD patients but not in the general population. However, additional well-designed studies are required to support the current findings.

Impact of Body Mass Index on the Association of Ankle-Brachial Index With All-Cause and Cardiovascular Mortality: Results from the National Health and Nutrition Examination Survey

OBJECTIVE

To assess the influence of body-mass index (BMI) on the association of ankle-brachial index (ABI) with mortality.

PATIENTS AND METHODS

We conducted a prospective study of National Health and Nutrition Examination Survey participants enrolled from January 1, 1999 to December 31, 2002 with BMI and ABI data available. ABI categories were <0.9 (low), 0.9 to 1.3 (reference), and >1.3 (high). BMI categories were <30 kg/m² (nonobese) and ≥30 kg/m² (obese). Cardiovascular (CV) and all-cause mortality were assessed by National Death Index records. Cox proportional-hazards models and Kaplan-Meier survival estimates were used to compare groups.

RESULTS

In total, 4614 subjects were included, with mean age 56±12 years and BMI 28±6 kg/m². Median follow-up was 10.3 years (interquartile range [IQR]: 9.3 to 11.4 years). Low and high ABI were present in 7% and 8%, respectively. After adjustment, low ABI was associated with increased all-cause and CV mortality in nonobese (hazard ratio [HR] 1.5, 95% CI, 1.1-2.1 for all-cause and 3.0 [1.8-5.1] for CV mortality) and obese individuals (1.8 [1.2-2.7] and 2.5 [1.2-5.6], respectively) compared with reference. High ABI was associated with increased CV mortality in nonobese (2.2 [1.1-4.5]) but not obese patients; it was not associated with all-cause mortality overall or when stratified by BMI.

CONCLUSION

In a US cohort, weight influenced the prognostic significance of high ABI. This may be related to technical factors reducing compressibility of the calf arteries in obese persons compared with those who are nonobese.

Ankle-brachial index and physical function in older individuals: The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND AND AIMS

Most prior studies investigating the association of lower extremity peripheral artery disease (PAD) with physical function were small or analyzed selected populations (e.g., patients at vascular clinics or persons with reduced function), leaving particular uncertainty regarding the association in the general community.

METHODS

Among 5262 ARIC participants (age 71-90 years during 2011-2013), we assessed the cross-sectional association of ankle-brachial index (ABI) with the Short Physical Performance Battery (SPPB) score (0-12), its individual components (chair stands, standing balance, and gait speed) (0-4 points each), and grip strength after accounting for potential confounders, including a history of coronary disease, stroke, or heart failure.

RESULTS

There were 411 participants (7.8%) with low ABI ≤0.90 and 469 (8.9%) participants with borderline low ABI 0.91-1.00. Both ABI ≤0.90 and 0.91-1.00 were independently associated with poor physical function (SPPB score ≤6) compared to ABI 1.11-1.20 (adjusted odds ratio 2.10 [95% CI 1.55-2.84] and 1.86 [1.38-2.51], respectively). The patterns were largely consistent across subgroups by clinical conditions (e.g., leg pain or other cardiovascular diseases), in every SPPB component, and for grip strength. ABI >1.3 (472 participants [9.0%]), indicative of non-compressible pedal arteries, was related to lower physical function as well but did not necessarily reach significance.

CONCLUSIONS

In community-dwelling older adults, low and borderline low ABI suggestive of PAD were independently associated with poorer systemic physical function compared to those with normal ABI. Clinical attention to PAD as a potential contributor to poor physical function is warranted in community-dwelling older adults.

Lower Extremity Peripheral Artery Disease and Quality of Life Among Older Individuals in the Community

Background

Evidence regarding the association of lower extremity peripheral arterial disease with quality of life (QOL) is mainly from selected clinical populations or relatively small clinical cohorts. Thus, we investigated this association in community‐derived populations.

Methods and Results

Using data of 5115 participants aged 66 to 90 years from visit 5 (2011‐2013) of the Atherosclerosis Risk in Communities Study, we quantified the associations of ankle‐brachial index (ABI) with several QOL parameters, including 12‐item Short‐Form Health Survey (SF‐12), after accounting for potential confounders using linear and logistic regression models. Peripheral arterial disease defined by an ABI <0.90 (n=402), was independently associated with a low SF‐12 Physical Component Summary score (−3.26 [95% CI −5.60 to −0.92]), compared to the ABI reference 1.10 to 1.19 (n=1900) but not with the Mental Component Summary score (−0.07 [−2.21 to 2.06]). A low ABI was significantly associated with poorer status of all SF‐12 physical domains (physical functioning, role‐physical, bodily pain, and general health) but only vitality out of 4 mental domains. Similarly, low ABI values were more consistently associated with other physically related QOL parameters (leisure‐time exercise/activity/walking) than mentally related parameters (significant depressive symptoms and hopeless feeling). Lower physical QOL was observed even in individuals with borderline low ABI (0.90 to 0.99; n=426).

Conclusions

Low ABI (even borderline) was independently associated with poor QOL, especially for physical components, in community‐dwelling older adults. QOL is a critical element for older adults, and thus, further studies are warranted to assess whether peripheral arterial disease‐specific management can improve QOL in older populations.

Clinical Characteristics and Outcomes of Patients with High Ankle-Brachial Index from the IMPACT-ABI Study

Background

Reduced ankle–brachial index (ABI) is a predictor of cardiovascular events. However, the significance of high ABI remains poorly understood. This study aimed to assess the characteristics and outcomes of patients with high ABI.

Methods

The IMPACT-ABI study was a retrospective cohort study that enrolled and examined ABI in 3,131 patients hospitalized for cardiovascular disease between January 2005 and December 2012. From this cohort, 2,419 patients were identified and stratified into two groups: high ABI (> 1.4; 2.6%) and normal ABI (1.0–1.4; 97.3%). The primary endpoint was the cumulative incidence of major adverse cardiovascular events (MACE), including cardiovascular-associated death, myocardial infarction, and stroke.

Results

Compared with the normal ABI group, patients in the high ABI group showed significantly lower body mass index (BMI) and hemoglobin level, but had higher incidence of chronic kidney disease and hemodialysis. Multivariate logistic regression analysis revealed that hemodialysis was the strongest predictor of high ABI (odds ratio, 6.18; 95% confidence interval (CI), 3.05–12.52; P < 0.001). During the follow-up (median, 4.7 years), 172 cases of MACE occurred. Cumulative MACE incidence in patients with high ABI was significantly increased compared to that in those with normal ABI (32.5% vs. 14.5%; P = 0.005). In traditional cardiovascular risk factors-adjusted multivariate Cox proportional hazard analysis, high ABI was an independent predictor of MACE (hazard ratio, 2.07; 95% CI, 1.02–4.20; P = 0.044).

Conclusion

Lower BMI, chronic kidney disease, and hemodialysis are more frequent in patients with high ABI. Hemodialysis is the strongest predictor of high ABI. High ABI is a parameter that independently predicts MACE.

Change in Ankle-Brachial Index Over Time in a Screened Japanese Cohort - The Okinawa Peripheral Arterial Disease Study

BACKGROUND

The temporal change in ankle-brachial index (ABI) in the general population, especially in those aged <40 years, remains unclear.

METHODS AND RESULTS

ABIs of 23,673 individuals were measured in 1-day health checkups between 2003 and 2010. Among them, 1,117 participants aged 28-76 years (mean 53±9 years) whose ABI was measured at least twice within an interval of ≥4 years (mean: 4.9 years) were selected for this study. Baseline ABI was the lowest at age <40 years and increased with age. ABI significantly increased in participants aged <40 and 40-49 years, but not in participants aged 50-59 and ≥60 years. ABI increased in participants with borderline-low baseline ABI (0.9<ABI<1.0, 0.09; P<0.001) and normal baseline ABI (1.0≤ABI<1.2, 0.006; P=0.017). ABI decreased in participants with high-normal baseline ABI (1.2≤ABI<1.4, -0.04; P<0.001). Stepwise multivariate analysis revealed that ABI change was independently associated with baseline ABI (β=-0.566), height (β=0.162), body mass index (β=0.093), and sex (women, β=-0.08).

CONCLUSIONS

ABI was lowest at age <40 years and increased with age. In participants aged <50 years, ABI significantly increased over the mean observation period of 4.9 years. (Circ J 2016; 80: 2004-2009).

Association of High Ankle Brachial Index With Incident Cardiovascular Disease and Mortality in a High-Risk Population

OBJECTIVE

The objective of this present study is to determine whether high ankle brachial index (ABI) as compared with ABIs within reference limits is associated with an increased incidence of cardiovascular disease (CVD) events and all-cause mortality in a high-risk population and whether this association is the same for patients with and without diabetes mellitus or prevalent CVD.

APPROACH AND RESULTS

Seven thousand five hundred and thirty-eight patients with ABI>0.9 and either prevalent CVD or a high risk for CVD were selected from the Second Manifestations of Arterial Disease (SMART) study. Three hundred and thirty-six participants (4.5%) had high ABI (≥1.4 or incompressible). Higher age, male sex, higher body mass index, and diabetes mellitus were associated with higher prevalences of high ABI; smoking and higher non-high-density lipoprotein levels were associated with lower prevalences of high ABI. Cox proportional hazards models were fitted assessing the association of high ABI (as compared with ABI 0.9-1.4) with the risk of myocardial infarction, stroke, cardiovascular death, the combined outcome of these 3, and total mortality (median follow-up 6.9 years). After multivariable adjustment, high ABI was associated with an increased risk of myocardial infarction (hazard ratio 1.83 [95% confidence interval 1.22-2.76]), but not with stroke (hazard ratio 0.86 [95% confidence interval 0.44-1.69]), cardiovascular (hazard ratio 1.14 [95% confidence interval 0.70-1.84]), or all-cause mortality (hazard ratio 0.95 [95% confidence interval 0.67-1.34]). Associations of high ABI with CVD outcomes tended to be stronger in patients with diabetes mellitus but without statistically significant interactions.

CONCLUSIONS

In a high-risk population, the presence of an ABI≥1.4 was associated with an increased risk for myocardial infarction, but not with stroke, all-cause, or vascular mortality.

Ankle-Brachial Index Testing at the Time of Stress Testing in Patients Without Known Atherosclerosis

BACKGROUND

Individuals referred for stress testing to identify coronary artery disease may have nonobstructive atherosclerosis, which is not detected by stress tests. Identification of increased risk despite a negative stress test could inform prevention efforts. Abnormal ankle-brachial index (ABI) is associated with increased cardiovascular risk.

HYPOTHESIS

Routine ABI testing in the stress laboratory will identify unrecognized peripheral arterial disease in some patients.

METHODS

Participants referred for stress testing without known history of atherosclerotic disease underwent ABI testing (n = 451). Ankle-brachial index was assessed via simultaneous arm and leg pressure using standard measurement, automated blood-pressure cuffs at rest. Ankle-brachial index was measured after exercise in 296 patients and 30 healthy controls. Abnormal postexercise ABI was defined as a >20% drop in ABI or fall in ankle pressure by >30 mm Hg.

RESULTS

Overall, 2.0% of participants had resting ABI ≤0.90, 3.1% had ABI ≥1.40, and 5.5% had borderline ABI. No patient with abnormal or borderline ABI had an abnormal stress test. Participants who met peripheral arterial disease screening criteria (age ≥65 or 50-64 with diabetes or smoking) tended toward greater frequency of low ABI (2.9% vs 1.0%; P = 0.06) and were more likely to have borderline ABI (0.91 to 0.99; 7.8% vs 2.9%; P = 0.006). Postexercise ABI was abnormal in 29.4% of patients and 30.0% of controls (P not significant).

CONCLUSIONS

Ankle-brachial index screening at rest just before stress testing detected low ABI in 2.0% of participants, all of whom had negative stress tests.

Complex nonlinear autonomic nervous system modulation link cardiac autonomic neuropathy and peripheral vascular disease

BACKGROUND

Physiological interactions are abundant within, and between, body systems. These interactions may evolve into discrete states during pathophysiological processes resulting from common mechanisms. An association between arterial stenosis, identified by low ankle-brachial pressure index (ABPI) and cardiovascular disease (CVD) as been reported. Whether an association between vascular calcification-characterized by high ABPI and a different pathophysiology-is similarly associated with CVD, has not been established. The current study aims to investigate the association between ABPI, and cardiac rhythm, as an indicator of cardiovascular health and functionality, utilizing heart rate variability (HRV).

METHODS AND RESULTS

Two hundred and thirty six patients underwent ABPI assessment. Standard time and frequency domain, and non-linear HRV measures were determined from 5-min electrocardiogram. ABPI data were divided into normal (n = 101), low (n = 67) and high (n = 66) and compared to HRV measures.(DFAα1 and SampEn were significantly different between the low ABPI, high ABPI and control groups (p < 0.05).

CONCLUSION

A possible coupling between arterial stenosis and vascular calcification with decreased and increased HRV respectively was observed. Our results suggest a model for interpreting the relationship between vascular pathophysiology and cardiac rhythm. The cardiovascular system may be viewed as a complex system comprising a number of interacting subsystems. These cardiac and vascular subsystems/networks may be coupled and undergo transitions in response to internal or external perturbations. From a clinical perspective, the significantly increased sample entropy compared to the normal ABPI group and the decreased and increased complex correlation properties measured by DFA for the low and high ABPI groups respectively, may be useful indicators that a more holistic treatment approach in line with this more complex clinical picture is required.

The Ankle-Brachial Index Is Related to Left Ventricular Ejection Fraction in Bonnet Macaques

Low ankle-brachial index (ABI) is a marker of peripheral arterial disease associated with higher cardiovascular risk. ABI has been found to be influenced by left ventricular ejection fraction (LVEF), but this relation is confounded by atherosclerosis. <b><i>Objectives:</i></b> Since nonhuman primates have a low incidence of atherosclerosis, we sought to evaluate the effect of LVEF on ABI in 24 healthy female bonnet macaques (age 83 ± 21 months). <b><i>Methods:</i></b> LVEF was determined by echocardiography during anesthesia with ketamine. ABI was determined using automatic blood pressure cuff. <b><i>Results:</i></b> Mean LVEF was 73 ± 6%. Mean ABI was 1.03 (range 0.78-1.17) with similar right and left lower limb values (p = 0.78). On univariate analysis, mean ABI was significantly correlated with LVEF (r = 0.58, p = 0.003) but not with age, crown-rump length or weight. Mean LVEF increased in a stepwise manner from lowest to highest ABI tertile (68 ± 6 vs. 73 ± 4 vs. 77 ± 5%, p = 0.008). On ordinal regression and forced multivariate linear analyses, ABI status was independently related to LVEF. <b><i>Conclusions:</i></b> ABI is influenced by left ventricular systolic function but not age, height, weight or mass index in bonnet macaques. Left ventricular systolic function should be accounted for when considering ABI measurements.

Combination of high ankle-brachial index and hard coronary heart disease Framingham Risk Score in predicting the risk of ischemic stroke in general population

Our previous study showed that the patients with more metabolic risk factors had higher risk of high ankle–brachial index (ABI), but the relationship between high ABI and the risk of severe cardiovascular and cerebrovascular diseases is still under debate. This study aims to evaluate this association in the general population. 1486 subjects of South China were recruited in the study. 61 subjects were defined as high ABI group (ABI≥1.3) and 65 subjects were randomly selected as normal ABI group (0.9<ABI<1.3). Biochemical parameters, clinical characteristics and 10-year hard coronary heart disease (HCHD) Framingham Risk Score (FRS) were compared between two groups. The results showed that the 10-year HCHD FRS of high ABI group was significantly higher than normal ABI group (7.87±6.11 vs. 3.98±2.90%, P<0.001). There was a positive correlation between ABI value and HCHD FRS in overweight participants (R = 0.576, P<0.01). The prevalence of ischemic stroke was higher in high ABI group than normal ABI group (21.3% vs. 6.2%, P<0.05), and it was higher in participants with HCHD FRS≥6% than those with HCHD FRS<6% (19.1% vs. 6.9%, P<0.05). Moreover, the prevalence of ischemic stroke was higher in participants with high ABI and HCHD FRS≥6% than those with normal ABI and HCHD FRS<6% (26.7% vs. 4.1%, P<0.05). BMI, hypertension, hsCRP and smoking were proved to be the independent factors and effective predictors for high ABI (P<0.05). In conclusion, high ABI combined with high HCHD FRS should be a potential predictor of ischemic stroke in the general population of South China.

Clinical detection, risk factors, and cardiovascular consequences of medial arterial calcification: a pattern of vascular injury associated with aberrant mineral metabolism

Patients with end-stage renal disease are characterized by extensive vascular calcification and high cardiovascular disease (CVD) risk. Calcification in end-stage renal disease patients represents at least two distinct pathologic processes. Calcification within the tunica intima frequently is associated with lipid-laden, flow-limiting atherosclerotic plaques. These appear as spotty areas of calcification interspersed with noncalcified arterial segments on plain radiography and generally are found near arterial branch points in medium-sized conduit arteries. In contrast, medial arterial calcification (MAC) involves deeper layers of the arterial wall; tends to affect the artery diffusely, appearing as a linear contiguous tram-track pattern of calcification on plain radiography; and often involves smaller muscular arteries such as the radial artery, intermammary arteries, and arteries in the ankle and foot. Both are related to CVD events, but potentially through different mechanisms. Atherosclerotic calcification may be marking the total burden of atherosclerosis, whereas MAC may lead to arterial stiffness and left ventricular hypertrophy. Existing data suggest that altered mineral metabolism may promote MAC, whereas heightened inflammation and oxidative stress contribute to atherosclerosis. Dysregulation of normal anticalcification factors and elastin degradation are common to both processes. Risk of vascular calcification also may be increased by the use of certain medications in the setting of chronic kidney disease. This review compares and contrasts known risk factors for MAC and atherosclerosis, describes existing and emerging technologies to distinguish between them, and reviews the existing literature linking each with CVD events in dialysis patients and in other settings.

Atherosclerosis and thromboembolic risk in atrial fibrillation: focus on peripheral vascular disease

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice. It results in a 5-fold increased risk for stroke and thromboembolism and is associated with a high morbidity and mortality. AF shares several risk factors and pathophysiological features with atherosclerosis. Hence AF is often complicated by a variety of other cardiovascular conditions. Indeed, peripheral vascular disease (PVD) is highly prevalent among AF patients and associates with increased mortality. Inclusion of PVD within stroke risk scoring systems such as the CHA2DS2-VASc score improves risk stratification of AF patients. Of note, PVD has not been previously well documented nor looked for in observational studies or clinical trials. The aim of this present review article is to provide an overview of the association between atherosclerosis (with particular focus on PVD) and AF as well as its complications.

Inflammation and oxidative stress are associated with the prevalence of high aankle-brachial index in metabolic syndrome patients without chronic renal failure

AIMS

High ankle-brachial index (ABI) is marker of increased cardiovascular morbidity and mortality, while the relationship and mechanism between high ABI and metabolic syndrome (MetS) are unclear. The objectives of this study were to determine the relationship and possible mechanism of MetS with high ABI.

METHODS

341 participants without CRF were recruited. Among these participants, 58 participants (ABI ≥ 1.3) were include in high ABI group and the other 283 participants (0.9 < ABI < 1.3) were include in normal ABI group. Furthermore, these 341 participants were also divided into MetS group (n = 54) and non-MetS group (n = 287). All participants received examinations including body mass index (BMI), ABI and related biochemical parameters.

RESULTS

Compared with non-MetS group, the prevalence of high ABI was higher in MetS group (27.8% vs. 15%, p < 0.05). Participants with 3-4 metabolic risk factors had higher prevalence of high ABI than those with 0-1 metabolic risk factors (27.8% vs. 12.7%, p < 0.05). The prevalence of high ABI in overweight participants was higher than those with normal body weight. And the participants with hypertension also had higher prevalence of high ABI than normotensive participants. BMI, high-sensitivity C-reactive protein (hsCRP) and superoxide dismutase (SOD) were all higher in high ABI group than normal ABI group (p < 0.05).

CONCLUSIONS

More metabolic risk factors have increased the risk of high ABI. Inflammation and oxidative stress are associated with prevalence of high ABI in metabolic syndrome patients without chronic renal failure.

Ankle brachial index as an independent predictor of mortality in anticoagulated atrial fibrillation

BACKGROUND

An abnormal ankle brachial index (ABI, the ratio of the ankle and the brachial systolic blood pressure) (≤ 0·90 or ≥ 1·4) suggests the presence of peripheral arterial disease (PAD) and has proposed as a marker of cardiovascular risk. We hypothesised that the ABI would predict mortality and adverse events in anticoagulated chronic nonvalvular AF patients.

METHODS

We recruited 287 consecutive anticoagulated outpatients with permanent or paroxysmal nonvalvular AF who were stabilised for 6 months on oral anticoagulation (Oral anticoagulation; INR 2·0-3·0). ABI was performed following a standard technique. Cox models were used to determine the association between ABI, and bleeding, cardiovascular events and mortality.

RESULTS

Median ABI was 1·09 (0·93-1·23) and 78 (27%) had an abnormal ABI. Abnormal ABI was associated with diabetes, heart failure and ischaemic heart disease (P = 0·006, 0·019 and 0·009, respectively), and a CHADS(2) score ≥ 2 (P = 0·016). Median follow-up was 861 (718-1016) days, during 21(7%) presented an adverse cardiovascular event, 23 (8%) major bleeding events and 18 (6%) died. ABI was an independent predictor for all-cause mortality, even after adjusting for CHADS(2) score (Cox multivariable regression analysis, HR 2·76(1·08-7·06), P = 0·033). Abnormal ABI was significantly associated with major haemorrhagic events [HR: 2·47(1·01-6·04); P = 0·047], even after adjustment for HAS-BLED score.

CONCLUSION

Abnormal ABI is common in AF patients, and ABI was an independent predictor for all-cause mortality, even after adjusting for CHADS(2) score. ABI was an independent predictor for major bleeding, even after adjusting for the HAS-BLED score. ABI could be a useful tool for improving risk stratification of anticoagulated AF patients.

The role of ankle brachial index and carotid intima-media thickness in vascular risk stratification

PURPOSE OF REVIEW

To summarize recent findings on the role of ankle brachial index (ABI) and carotid intima-media thickness (cIMT) in vascular risk stratification.

RECENT FINDINGS

The combination of either ABI or cIMT with the Framingham risk score does not appear to improve risk stratification more than the Framingham risk score alone.

SUMMARY

ABI and cIMT are well studied markers of atherosclerotic burden. Considerable evidence shows that they both are independently associated with increased vascular morbidity and mortality. However, their value in identifying high-risk patients among those with low or intermediate estimated risk appears to be limited. Regarding cIMT, this might be because cIMT is mostly a marker of early atherosclerosis. On the contrary, peripheral arterial disease (i.e. ABI <0.9) develops mostly in patients who already have high estimated vascular risk (e.g. elderly smokers or diabetic patients). Nevertheless, ABI is inexpensive, can be performed quickly and has high validity and good reproducibility, in contrast to the technical equipment and expertise required for measuring cIMT. Accordingly, ABI should be measured in patients at risk for peripheral arterial disease but not in all intermediate-risk patients indiscriminately. Finally, it has not been evaluated whether adding ABI or cIMT to the Framingham risk equation to guide management decisions will prevent more events than the use of the Framingham risk equation alone. Before the wider implementation of ABI or cIMT for risk stratification, this critical question has to be answered.

Usefulness of baseline obesity to predict development of a high ankle brachial index (from the Multi-Ethnic Study of Atherosclerosis)

An abnormally high ankle-brachial index (ABI) is associated with increased all-cause and cardiovascular mortality. The relation of obesity to incident high ABI has not been characterized. The aim of this study was to investigate the hypothesis that increased obesity-quantified by body weight, body mass index, waist circumference, and waist-to-hip-ratio-is positively associated with a high ABI (≥1.3) and with mean ABI increases over a 4-year follow-up. Prevalence and incidence ratios for a high ABI were obtained for 6,540 and 5,045 participants, respectively, in the Multi-Ethnic Study of Atherosclerosis (MESA), using log-binomial regression models adjusted for demographic, cardiovascular, and inflammatory and novel risk factors. Linear regression was used to analyze mean ABI change. The prevalence and incidence of a high ABI were significantly higher for the highest compared to the lowest quartile of every baseline measure of obesity, with weight and body mass index demonstrating the highest incidence ratios (2.7 and 2.4, respectively). All prevalence and incidence ratios were positive and graded across obesity quartiles and were persistent in the subpopulation without diabetes. In those with normal baseline ABI values, 1 MESA standard deviation increase in every baseline measure of obesity was associated with significant increases in mean ABI values. In conclusion, independent, positive, and graded associations of increasing obesity with prevalent and incident high ABI and with mean increases in ABI values over time were found. Weight and body mass index seemed to be at least as strongly, if not more strongly, associated with a high ABI than were measures of abdominal obesity.

A high ankle-brachial index is associated with increased aortic pulse wave velocity: the Czech post-MONICA study

Background: Ankle brachial index (ABI) has been increasingly used in general practice to identify individuals with low ABI at high cardiovascular risk. However, there has been no consensus on the clinical significance of high ABI. The aim of our study was to compare aortic stiffness as a marker of cardiovascular risk in individuals with low (<1.0), normal (1.0–1.4), and high ABI (>1.4).

Methods: A total of 911 individuals from the Czech post-MONICA study (a randomly selected 1% representative population sample, aged 54 ± 13.5 years, 47% of men) were examined. ABI was measured using a handheld Doppler and aortic pulse wave velocity (aPWV) using the Sphygmocor device.

Results: Of the 911 individuals, 28 (3.1%) had low ABI and 23 (2.5%) high ABI. There was a U-shaped association between aPWV and ABI. aPWV was significantly higher in individuals with low and high ABI compared with the normal ABI group (11.1 ± 2.8, 8.3 ± 2.3, p < 0.001; 10.8 ± 2.5, 8.3 ± 2.3 m/s, p < 0.001, respectively). In a model adjusted for age, sex, systolic, diastolic, mean blood pressure and examiner, aPWV remained increased in both extreme ABI groups compared with the normal ABI group. In logistic regression analysis, aPWV together with glucose level, male sex, and a history of deep venous thrombosis were independent predictors of high ABI, while cholesterol was not.

Conclusion: This is the first study showing increased aortic stiffness in individuals with high ABI, presumably responsible for increased left ventricular mass described previously in this group. These findings suggest increased cardiovascular risk of high ABI individuals.

Peripheral artery disease assessed by ankle-brachial index in patients with established cardiovascular disease or at least one risk factor for atherothrombosis--CAREFUL study: a national, multi-center, cross-sectional observational study

BACKGROUND

To investigate the presence of peripheral artery disease (PAD) via the ankle brachial index (ABI) in patients with known cardiovascular and/or cerebrovascular diseases or with at least one risk factor for atherothrombosis.

METHODS

Patients with a history of atherothrombotic events, or aged 50-69 years with at least one cardiovascular risk factor, or > = 70 years of age were included in this multicenter, cross-sectional, non-interventional study (DIREGL04074). Demographics, medical history, physical examination findings, and physician awareness of PAD were analyzed. The number of patients with low ABI (< = 0.90) was analyzed.

RESULTS

A total of 530 patients (mean age, 63.4 ± 8.7 years; 50.2% female) were enrolled. Hypertension and dyslipidemia were present in 88.7% and 65.5% of patients, respectively. PAD-related symptoms were evident in about one-third of the patients, and at least one of the pedal pulses was negative in 6.5% of patients. The frequency of low ABI was 20.0% in the whole study population and 30% for patients older than 70 years. Older age, greater number of total risk factors, and presence of PAD-related physical findings were associated with increased likelihood of low ABI (p < 0.001). There was no gender difference in the prevalence of low ABI, PAD symptoms, or total number of risk factors. Exercise (33.6%) was the most common non-pharmacological option recommended by physicians, and acetylsalicylic acid (ASA) (45.4%) was the most frequently prescribed medication for PAD.

CONCLUSION

Our results indicate that advanced age, greater number of total risk factors and presence of PAD-related physical findings were associated with increased likelihood of low ABI. These findings are similar to those reported in similar studies of different populations, and document a fairly high prevalence of PAD in a Mediterranean country.

Coronary artery calcium, brain function and structure: the AGES-Reykjavik Study

BACKGROUND AND PURPOSE

Several cardiovascular risk factors are associated with cognitive disorders in older persons. Little is known about the association of the burden of coronary atherosclerosis with brain structure and function.

METHODS

This is a cross-sectional analysis of data from the Age, Gene, Environment Susceptibility (AGES)-Reykjavik Study cohort of men and women born 1907 to 1935. Coronary artery calcification (CAC), a marker of atherosclerotic burden, was measured with CT. Memory, speed of processing, and executive function composites were calculated from a cognitive test battery. Dementia was assessed in a multistep procedure and diagnosed according to international guidelines. Quantitative data on total intracranial and tissue volumes (total, gray matter volume, white matter volume, and white matter lesion volume), cerebral infarcts, and cerebral microbleeds were obtained with brain MRI. The association of CAC with dementia (n=165 cases) and cognitive function in nondemented subjects (n=4085), and separately with MRI outcomes, was examined in multivariate models adjusting for demographic and vascular risk factors. Analyses tested whether brain structure mediated the associations of CAC to cognitive function.

RESULTS

Subjects with higher CAC were more likely to have dementia and lower cognitive scores, more likely to have lower white matter volume, gray matter volume, and total brain tissue, and to have more cerebral infarcts, cerebral microbleeds, and white matter lesions. The relations of cognitive performance and dementia to CAC were significantly attenuated when the models were adjusted for brain lesions and volumes.

CONCLUSIONS

In a population-based sample, increasing atherosclerotic load assessed by CAC is associated with poorer cognitive performance and dementia, and these relations are mediated by evidence of brain pathology.

Relation of the ankle brachial index to left ventricular ejection fraction

Low and high ankle brachial index (ABI) values are both a marker of peripheral arterial disease and associated with greater cardiovascular disease event rates. The objective of the present study was to determine whether the ABI is associated with left ventricular (LV) systolic function. We studied 175 patients (age 67 +/- 13 years, 58% men) referred for ABI determination who had had the LV ejection fraction (EF) determined using echocardiography within 14 days. The mean LVEF was 47 +/- 13%, mean ABI for the right leg was 0.93 +/- 0.32, and the mean ABI for the left leg was 0.94 +/- 0.26. Of the 175 patients, 91 (52%) had a low, 69 (39%) had a normal, and 15 (9%) had a high ABI. The mean LVEF increased in a stepwise manner from the low, to normal, to abnormally high ABI groups (43 +/- 13% vs 51 +/- 12% vs 57 +/- 5%, respectively; p <0.01). On ordinal regression analysis, ABI status was independently related to LVEF. For each 1% increase in LVEF, the odds of being in the higher category of ABI increased by 1.08 (95% confidence interval 1.02 to 1.12, p = 0.002). No significant interaction was seen between coronary artery disease and LVEF on the ABI (p = 0.48). In conclusion, the ABI might be influenced by LV systolic function, independent of coronary disease. LVEF should be considered when ABI values are used to evaluate and monitor cardiovascular risk in patients.

[Usefulness of the ankle-arm index for detection of peripheral arterial disease in a working population of Junta de Andalucía at Málaga]

BACKGROUND AND OBJECTIVE

Detection of asymptomatic peripheral arterial disease increases the risk of vascular morbibity and mortality. We aimed to estimate the prevalence of clinical and subclinical peripheral arterial disease using the ankle-arm index (AAI) as diagnostic tool in a working population.

SUBJECTS AND METHOD

We included 450 workers, older than 50 years old, attending voluntary regular health check-up at Centro de Prevención de Riesgos Laborales de la Junta de Andalucía in Málaga (Spain). We recorded clinical and anthopometrical data. Blood samples were taken after an overnight fast. Vascular risk was calculated using Framinghan and SCORE scales. Every participant was asked for symptoms of intermittent claudicatio and AAI was measured. AAI was considered normal within 0.9-1.3 values.

RESULTS

Most of our workers were at low- or moderate vascular risk. Only 48 (10.6%) of individuals had an abnormal AAI: 9 (2%) showed an AAI<0.9 and 39 (8.6%) showed an AAI>1.3. An AAI<0.9 was found in 19% of those with a SCORE risk > or = 5%, and in 11% of those having a Framinghan risk > or = 20%. Intermittent claudication was present in 4 out of 9 (44%) of those having an AAI<0.9 and in 7 out of 402 (1.7%) with a normal AAI.

CONCLUSIONS

Systematic screening of peripheral arterial disease using the AAI is not recommended in active working population over 50 years-old of age. Thus, AAI measurement is indicated only for those individuals suffering from intermitent claudicatio and those who are at moderate- or high vascular risk.

Contemporary risk factor control and walking dysfunction in individuals with peripheral arterial disease: NHANES 1999-2004

BACKGROUND

Lower extremity peripheral arterial disease (PAD) is a coronary heart disease (CHD) risk equivalent. Selected studies have demonstrated less intense risk factor management and diminished mobility in individuals with PAD as compared to individuals with clinical recognized CHD. However, comparable data have not been reported from a nationally representative population.

OBJECTIVES

To assess the prevalence, treatment, and control of cardiovascular risk factors among individuals with PAD as defined by an ankle-brachial index (ABI) <0.90 (but without recognized CHD) as compared with individuals with recognized CHD (but without PAD). A second objective was to evaluate the diagnostic accuracy of measures of walking dysfunction to identify individuals with PAD.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed data from 7571 participants aged 40 or older who participated in the National Health and Nutrition Examination Survey (NHANES) 1999-2004, a nationally representative cross-sectional survey of the U.S. population.

RESULTS

The prevalence of PAD without CHD was 4.1% (95% CI 3.6-4.5) compared to 7.9% (7.1, 8.9) for CHD (without PAD). Hypertension prevalence was similar, but treatment and control rates were lower among individuals with PAD compared to CHD (treatment: 69% vs. 84%, p<0.001; control: 50% vs. 63%, p=0.01). Treatment of hypercholesterolemia was lower among individuals with PAD (54% vs. 79%, p<0.001) but control was similar (83% vs. 85%, p=0.78). Diabetes awareness, treatment, and control did not differ between the two groups. Walking mobility limitations were specific, but insensitive, for the identification of individuals with PAD.

CONCLUSION

PAD in the absence of clinically recognized CHD is under-treated and poorly controlled in the general U.S. population. Leg symptoms are not adequate to identify individuals with PAD, who are at high risk of ischemic events.

Ankle-Brachial Index and Extent of Atherosclerosis in Patients from the Middle East (the AGATHA-ME Study): A Cross-Sectional Multicenter Study

To assess the extent of atherothrombosis and the use of the ankle-brachial index (ABI) in populations from the Middle East, we conducted a multicenter study similar to AGATHA (a Global Atherothrombosis Assessment), AGATHA-ME, which included 1341 patients from 18 centers from 5 countries (United Arab Emirates, Kuwait, Qatar, Bahrain, and Oman). Patients were assigned to 2 groups: the with-disease and at-risk groups. Abnormal ABI (≤0.9) was seen in 31.5% of at-risk patients and 28.2% of with-disease patients. Patients with peripheral arterial disease had the highest frequency of abnormal ABI (77.6%), with 97.8 negative predictive value. The AGATHA-ME study confirms that atherothrombosis disease often occurs at more than 1 site. The ABI is related to the risk factor profile and to the site and extent of atherothrombosis. Gender and diabetes mellitus are associated with the worst parameters.

Peripheral arterial disease in HIV patients older than 50 years of age

Our objective was to analyze the prevalence of peripheral arterial disease (PAD) in HIV patients at risk and to compare them with the general population. All HIV patients older than 50 years who attended our unit from October 2005-July 2006 and all persons attending for an annual medical checkup at an employees' insurance association during the same period were invited to participate in the study. Of the latter (n = 407), a person of the same sex and age (+/-5 years) was included for each HIV patient. PAD was assessed by the ankle-brachial index (ABI) in all subjects, and all completed the Edinburgh questionnaire. Ninety-nine HIV patients and 99 persons from the general population of the same age and sex were included in the study. The HIV patients had a greater prevalence of dyslipidemia, diabetes, and PAD, which was symptomatic in five of them and in one subject from the general population. Patients with HIV infection older than 50 had a high prevalence of PAD, and as it was asymptomatic in half the cases, an ABI may be performed in this population to actively look for PAD. Control of cardiovascular risk factors and the use of such drugs as platelet antiaggregation agents should therefore be optimized in this population.

A high ankle-brachial index is associated with increased cardiovascular disease morbidity and lower quality of life

OBJECTIVES

The purpose of this study is to determine if an ankle-brachial index (ABI) >or=1.40 is associated with reduced quality of life (QoL).

BACKGROUND

Ankle-brachial index values >or=1.40 have been associated with some cardiovascular disease (CVD) risk factors and increased mortality, but the relationship to other disease morbidity such as reduced QoL has not been previously evaluated.

METHODS

The PARTNERS (PAD Awareness, Risk and Treatment: New Resources for Survival) program was a national cross-sectional study of 7,155 patients age >50 years recruited from 350 primary care sites. All sites performed the ABI using a Doppler device and a standardized technique.

RESULTS

A total of 296 subjects had an ABI >or=1.40 in at least 1 leg, and 4,420 had an ABI between 0.90 and 1.40. Diabetes, male gender, and waist circumference were positively associated with a high ABI, and smoking and dyslipidemia were inversely associated with a high ABI. After adjustment for age, gender, and the traditional CVD risk factors, and accounting for multiple comparisons, the high ABI group had significantly higher odds for foot ulcers (p < 0.005) and borderline associations with heart failure, stroke, and neuropathy. After the same adjustments and adjusting for patients with other CVD, the high ABI group scored 2.0 points lower on the physical component scale on the Medical Outcomes Study Standard Form-36 and 5.5 points lower on the Walking Impairment Questionnaire walking distance domain (p < 0.05 for both).

CONCLUSION

Individuals with a high ABI have higher odds for foot ulcers and neuropathy, as well as lower scores on some physical functioning QoL domains.

Aortic augmentation index is associated with the ankle-brachial index: a community-based study

BACKGROUND

Increased arterial stiffness has been associated with greater risk of cardiovascular events. We investigated whether aortic augmentation index (AIx), a measure of arterial stiffness and wave reflection, was associated with the ankle-brachial index (ABI), a measure of peripheral arterial disease (PAD).

METHOD

AIx and ABI were measured in a community-based sample of 475 adults without prior history of heart attack or stroke (mean age 59.3 years, 46.5% men). Radial artery pulse waveforms were obtained by applanation tonometry and an ascending aortic pressure waveform derived by a transfer function. AIx is the difference between the first and second systolic peak of the ascending aortic pressure waveform indexed to the central pulse pressure. ABI was measured using a standard protocol, and subjects with non-compressible vessels (ABI >1.5) were excluded from the analyses. Multivariable linear and logistic generalized estimating equations (GEE) analyses were used to assess whether AIx was associated with ABI and ABI <1.00, respectively, independent of conventional risk factors.

RESULTS

Mean (+/-S.D.) values were: AIx, 29.3+/-11.6%; ABI, 1.12+/-0.13; 59 (12.4%) participants had an ABI <1.00. Variables associated with a lower ABI (and ABI <1.00) included older age, shorter height, female sex, higher total cholesterol, hypertension medication use, history of smoking, and higher AIx. After adjustment for mean arterial pressure and the above variables, higher AIx remained associated with a lower ABI (P=0.015) and ABI <1.00 (P=0.002). A significant interaction (P=0.007) was present between AIx and age in the prediction of ABI; the (inverse) association of AIx with ABI was stronger in older subjects (>65 years).

CONCLUSION

AIx, a measure of arterial stiffness and wave reflection, was independently associated with a lower ABI in asymptomatic subjects from the community, and this association was modified by age.

The association of the ankle-brachial index with incident coronary heart disease: the Atherosclerosis Risk In Communities (ARIC) study, 1987-2001

BACKGROUND

Peripheral arterial disease (PAD), defined by a low ankle-brachial index (ABI), is associated with an increased risk of cardiovascular events, but the risk of coronary heart disease (CHD) over the range of the ABI is not well characterized, nor described for African Americans.

METHODS

The ABI was measured in 12186 white and African American men and women in the Atherosclerosis Risk in Communities Study in 1987-89. Fatal and non-fatal CHD events were ascertained through annual telephone contacts, surveys of hospital discharge lists and death certificate data, and clinical examinations, including electrocardiograms, every 3 years. Participants were followed for a median of 13.1 years. Age- and field-center-adjusted hazard ratios (HRs) were estimated using Cox regression models.

RESULTS

Over a median 13.1 years follow-up, 964 fatal or non-fatal CHD events accrued. In whites, the age- and field-center-adjusted CHD hazard ratio (HR, 95% CI) for PAD (ABI<0.90) was 2.81 (1.77-4.45) for men and 2.05 (1.20-3.53) for women. In African Americans, the HR for men was 4.86 (2.76-8.47) and for women was 2.34 (1.26-4.35). The CHD risk increased exponentially with decreasing ABI as a continuous function, and continued to decline at ABI values > 1.0, in all race-gender subgroups. The association between the ABI and CHD relative risk was similar for men and women in both race groups. A 0.10 lower ABI increased the CHD hazard by 25% (95% CI 17-34%) in white men, by 20% (8-33%) in white women, by 34% (19-50%) in African American men, and by 32% (17-50%) in African American women.

CONCLUSION

African American members of the ARIC cohort had higher prevalences of PAD and greater risk of CHD associated with ABI-defined PAD than did white participants. Unlike in other cohorts, in ARIC the CHD risk failed to increase at high (>1.3) ABI values. We conclude that at this time high ABI values should not be routinely considered a marker for increased CVD risk in the general population. Further research is needed on the value of the ABI at specific cutpoints for risk stratification in the context of traditional risk factors.