Metabolic syndrome and vascular risk in patients with peripheral arterial occlusive disease

Lower Lean Mass Is Associated with Greater Arterial Stiffness in Patients with Lower Extremity Artery Disease

Background: Arterial stiffness is independently associated with lower extremity artery disease (LEAD). Although obesity is already known as an independent cardiovascular risk factor, it was found that, paradoxically, in patients diagnosed with cardiovascular disease, an increase in body mass index (BMI) was associated with a decrease in mortality. However, the underlying mechanism of this paradoxical association remain uncertain. In this study, we firstly hypothesize that arterial stiffness correlates with body mass; secondly, the underlying mechanism of the association for patients with LEAD is individual body composition, in particular, lean mass. Methods: The present study was performed as a single-center, prospective, observational analysis. A total of 412 patients with current or previously diagnosed LEAD (Rutherford Classification 2–4) were included, the cfPWV and AIx were measured as indices of arterial stiffness, and a body composition assessment was performed. Results: In male patients, there was a significantly negative correlation between the AIx and lean mass coefficient (p = 0.004, 95% CI: −0.28 (−0.48–0.09)). Conclusion: For patients with peripheral arterial disease, our data show that lower lean mass in male patients is associated with increased arterial stiffness as measured by the AIx. Therefore, progressive resistance training may be beneficial for the reduction in arterial stiffness in PAD patients in secondary prevention.

Lipoprotein-associated phospholipase A2 single-nucleotide polymorphisms and cardiovascular events in patients with coronary artery disease

AIMS

We tested the hypothesis that variations in the PLA2G7 gene encoding the lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme deemed to have proatherogenic activity, affect the Lp-PLA2 levels and predicts cardiovascular events.

METHODS

Using a prospective cohort study design, we investigated incident cardiovascular events as a function of the PLA2G7 gene for rs1805017, rs1805018, and rs1051931 single-nucleotide polymorphisms (SNPs) in 643 randomly selected white patients from the GENICA Study, who at baseline underwent coronary angiography, measurement of Lp-PLA2 mass and activity. Cardiovascular event-free survival was compared across the genotypes by Cox regression, propensity score matching, and haplotype analysis.

RESULTS

The rs1805018 SNP did not follow the Hardy-Weinberg equilibrium and was not further explored. The rs1805017 GG genotype had a lower Lp-PLA2 mass and a higher Lp-PLA2 activity, thus suggesting that this SNP is functional. Long-term follow-up (median 7.8 years) was obtained in 75% of the cohort and allowed recording of incident cardiovascular events in 25.8% of the patients. On Cox regression analysis, the common rs1805017 GG genotype predicted acute myocardial infarction (AMI) [hazard ratio 1.75, 95% confidence interval (CI) 1.03-2.99, P = 0.041]; this finding was confirmed on propensity score matching (82.6% AMI-free survival in GG vs. 94.4% in GA + AA, P = 0.003). The rs1805017 and rs1051931 G/G haplotype was also associated with AMI (52.7 vs. 42.2%, P = 0.026) and cardiovascular event incidence (49.5 vs. 41.7%, P = 0.025).

CONCLUSION

In high-risk coronary artery disease patients of European ancestry, the PLA2G7 rs1805017 GG genotype is associated with increased Lp-PLA2 plasma activity and AMI.

Metabolic syndrome in patients with peripheral arterial disease

BACKGROUND AND OBJECTIVE

The prevalence of metabolic syndrome (MS) in patients with peripheral arterial disease (PAD) and coronary or cerebrovascular disease is increasing, but it is not known whether this association also exists in patients with isolated PAD. The aim of the current study was to assess the prevalence of MS in patients with PAD who had no coronary or cerebrovascular disease, the prescription rate of evidence-based cardiovascular therapies and the attainment of therapeutic goals in patients with PAD and with and without MS.

PATIENTS AND METHODS

Multicenter, cross-sectional study of 3.934 patients aged ≥ 45 years with isolated PAD who were treated in primary care and specialized outpatient clinics during 2009. A diagnosis of PAD was reached for ankle brachial indices <0.9, a previous history of amputation or revascularization.

RESULTS

In the overall population, the mean age was 67.6 years, 73.8% were males and 63% had MS (95% CI 61.5-64.3%). Patients with MS had a higher prevalence of cardiovascular risk factors and comorbidities, more severe PAD and higher prescription rate of evidence-based cardiovascular therapies. After adjusting for risk factors and comorbidity, there was a more frequent use of renin-angiotensin system blockers, beta-blockers, diuretics and statins among the patients with MS. A lower percentage of patients with MS achieved the therapeutic goals for blood pressure (22% vs. 41.5%, p<0.001). Similarly, a lower percentage of patients with diabetes achieved the glycated hemoglobin goals (44% vs. 53.1%, p<0.001), with no differences in LDL-cholesterol levels (29.8% vs. 39.1%, p=0.265).

CONCLUSION

Patients with PAD have a high prevalence of MS. Patients with MS do not attain therapeutic goals as frequently as those without, despite taking more cardiovascular drugs.

Hind limb ischemia-reperfusion injury in diet-induced obese mice

BACKGROUND

Obesity is a major risk factor for the development of diabetes. Limb ischemia-reperfusion injury (IR) is a common clinical problem in diabetics who have compromised lower extremity perfusion. This study compared the histologic, metabolic, and functional outcomes after hind limb IR in diet-induced obese (DIO) and non-diabetic (ND) mice during the acute and the regenerative phases of IR.

METHODS

DIO and ND mice were subjected to 1.5 h unilateral hind limb ischemia followed by 1- or 28-d IR. Muscle morphology, metabolic, and genomic stress were evaluated at days 1 and 28 IR; Acute inflammation and thrombosis were only measured at day-1 IR. At day 28, IR, skeletal muscle contractility, and maturation were also assessed.

RESULTS

At day-1 IR, similar levels of acute muscle fiber necrosis were seen in both groups. DIO mice demonstrated substantially greater inflammatory, prothrombotic, and genomic stress responses, which were also associated with a greater reduction in energy substrates and Akt phosphorylation. At 28d, there was no difference in the peak forces generated in the hind limbs for the two groups. DIO mice had reduced fatigue resistance compared with ND and larger areas of fat accumulation although there was no significant difference in muscle fiber maturation.

CONCLUSIONS

DIO mice had an exacerbated acute response to IR with enhanced metabolic deficit, fat accumulation, and defective functional recovery during the regenerative phase of IR. These changes in fatigue resistance reflect compromised functional recovery after IR injury and have relevance for the functional recovery of patients with metabolic syndrome and insulin resistance.

Body mass index is inversely associated with mortality in patients with peripheral vascular disease

BACKGROUND

Current guidelines contain no advice on how to manage obesity and underweight in patients with peripheral vascular disease (PVD).

OBJECTIVES

The aim of this study was to assess the association of underweight, overweight and obesity with mortality in patients with PVD.

PATIENTS AND METHODS

We recruited 1472 patients with a broad range of presentations of PVD. Underweight, overweight and obesity were defined by body mass index (BMI) and associated with mortality using Kaplan Meier and Cox proportional hazard analyses.

RESULTS

Survival at 3 years was 37.5, 78.1, 86.8 and 87.0% for patients that were underweight, normal weight, overweight and obese at recruitment, respectively, p<0.001. Patients that were underweight had approximately twice the risk of dying (RR 2.15, 95% CI 1.31-3.55, p=0.003), while patients that were overweight (RR 0.67, 95% CI 0.49-0.91, p=0.011) or obese (RR 0.59, 95% CI 0.41-0.85, p=0.005) had approximately half the risk of dying, after adjustment for other risk factors and using normal weight subjects as the reference group. 823 patients had waist circumference measured at recruitment. Patients with waist circumference in the top quartile had half the risk of dying (RR 0.50, 95% CI 0.26-0.98, p=0.045). In 267 patients we assessed the relationship between BMI and abdominal fat volumes using computed tomography. BMI was highly correlated with both intra-abdominal and subcutaneous fat volumes.

CONCLUSIONS

Obesity whether assessed by BMI or central fat deposition is associated with reduced risk of dying in patients with established PVD. Underweight is highly predictive of early mortality in patients with PVD.

Biology of metabolic syndrome in a vascular patient

Metabolic syndrome is highly prevalent in vascular patients and has a significant impact on the outcomes of vascular interventions. It comprises of a set of metabolically driven risk factors, including truncal obesity, dyslipidemia, elevated blood pressure and elevated fasting blood glucose. Increased insulin resistance within the context of obesity and hypertension contributes to atherogenic dyslipidemia, hyperglycemia, and prothrombotic and proinflammatory states which lead to the adverse impact of metabolic syndrome on the response to injury and on atherosclerotic disease progression. This review focuses on the complex biology of metabolic syndrome and its relevance to management of vascular patients, including outcomes and implications for the coronary, cerebrovascular and lower-extremity vascular beds.

Low density lipoprotein cholesterol is inversely correlated with abdominal visceral fat area: a magnetic resonance imaging study

Background

Visceral Fat Area (VFA) is an independent predictor of coronary disease. While low density lipoprotein cholesterol (LDL-C) is used to determine risk and guide therapy, its accuracy fails in obese patients who may have low LDL-C despite high VFA.

Objective

We sought to describe the relationship between VFA, LDL-C and to describe shifting cholesterol metabolism with increasing VFA.

Methods

42 High-risk vascular patients not on lipid-lowering therapy provided a fasting lipid profile and underwent magnetic resonance imaging (MRI) to quantify VFA and subcutaneous fat area (SFA) at the L4-L5 disc. Comparisons: 1. Correlation between VFA, SFA, LDL-C and the standard lipid panel 2. Correlation between VFA, SFA and markers of cholesterol synthesis (desmosterol, lathosterol) and cholesterol absorption (cholestanol, sitosterol).

Results

VFA was inversely correlated with LDL-C (r = -0.348) indicating potential discordance between cardiovascular risk and LDL-C. However, VFA was appropriately correlated with other markers of increased risk: r = -0.361 with HDL-C, r = 0.503 with VLDL-C, r = 0.499 with TG (all p < 0.05). VFA did not correlate significantly with non-HDL-C. VFA correlated positively with cholesterol synthesis markers (desmosterol, lathosterol) and negatively with an absorption marker (cholestanol).

Conclusions

LDL-C is inversely correlated with VFA and this may explain the loss of the relationship between LDL-C and cardiovascular events in the obese. While Non-HDL-C did not correlate positively with VFA, the absence of a negative correlation suggests that it may be a more appropriate lipid target in an increasingly obese world.

MRI sagittal abdominal diameter is a stronger predictor of metabolic syndrome than visceral fat area or waist circumference in a high-risk vascular cohort

Objective:

To determine whether sagittal abdominal diameter (SAD) is associated with the metabolic syndrome independently of visceral fat area (VFA) and waist circumference (WC).

Methods:

Forty-three high-risk vascular patients were evaluated for metabolic syndrome criteria and underwent magnetic resonance imaging (MRI) to quantify SAD and VFA at the L4–L5 disc.

Comparisons:

1. Baseline differences in patients with and without the metabolic syndrome 2. Forward binary logistic regression analysis of predictors of the metabolic syndrome with SAD, VFA and WC as independents 3. Correlates of SAD.

Results:

Patients with metabolic syndrome had greater SAD, VFA and WC than patients without the metabolic syndrome (P < 0.01). Of SAD, VFA and WC, only SAD was associated with metabolic syndrome on forward binary logistic regression; beta 0.68, Wald’s statistic 10.8 (P = 0.001) and c-statistic 0.89 (P < 0.001). A > 22.7 cm SAD threshold identified metabolic syndrome with a 91% sensitivity and 80% specificity. SAD correlated with waist circumference (r = 0.918), high-density lipoprotein-cholesterol (r = −0.363), triglyceride (r = 0.401), fasting glucose (r = 0.428) and the QUICK index of insulin sensitivity (r = −0.667) (all P < 0.05).

Conclusions:

MRI-measured SAD is associated with the metabolic syndrome and renders the current gold standard of VFA redundant. This measure of obesity-related cardiovascular risk requires validation and evaluation in a prospective cohort.

Liver fat percent is associated with metabolic risk factors and the metabolic syndrome in a high-risk vascular cohort

Objective

To determine whether liver fat percent (LFP) is associated with the metabolic syndrome independently of visceral fat area (VFA).

Methods

43 High-risk vascular patients not on lipid-lowering therapy were evaluated for the Adult Treatment Panel III (ATPIII) metabolic syndrome criteria and underwent magnetic resonance imaging (MRI) to quantify VFA and subcutaneous fat area (SFA) at the L4-L5 disc and liver magnetic resonance spectroscopy (MRS) to quantify LFP. Comparisons: 1. Baseline differences in patients with and without the metabolic syndrome 2. Forward binary logistic regression analysis of predictors of the metabolic syndrome with VFA, SFA and LFP as independents 3. Correlates of LFP.

Results

43 patients were included in analysis. Patients with metabolic syndrome had greater VFA, SFA and LFP than patients without the metabolic syndrome (all p < 0.01). Of VFA, SFA and LFP, only LFP was associated with the diagnosis of the metabolic syndrome on forward binary logistic regression with an OR of 1.17 per 1% increase in LFP (p = 0.015). A 4% LFP threshold identified the metabolic syndrome with 84% sensitivity and 82% specificity. LFP correlated with waist circumference (r = 0.768), HDL-cholesterol (r = -0.342), triglyceride (r = 0.369), fasting glucose (r = 0.584) and the QUICK Index of insulin sensitivity (r = -0.679) (all p < 0.05)

Conclusions

LFP is associated with the metabolic syndrome and renders the current gold standard of VFA redundant in this analysis. This measure of obesity-related cardiovascular risk requires further validation and evaluation in a prospective cohort.

[Peripheral arterial disease with lower limb claudication: Medical treatment]

Whereas the complaint from a patient with intermittent arterial claudication is walking impairment, prognosis is linked to an increased risk of cardiovascular ischemic events due to the diffuse nature of the atherosclerosis. The objectives of the medical treatment therefore include improvement of walking limit, prevention of myocardial infarction, stroke and cardiovascular death, and preventive measures to avoid progression to critical lower limb ischemia. The key areas of treatment focus on smoking cessation, exercise rehabilitation, with supervised therapy if possible, cardiovascular risk prevention with antiplatelet drugs, statins and angiotensin converting enzymes, and correction of atherosclerotic risk factors with well-defined targets (LDL less than 1g/L, HDL greater than 0.4g/L, HbA(1c) less than 6.5%, brachial blood pressure less than 140/90 or 130/80mmHg in case of diabetes or renal insufficiency, body mass index less than 25kg/m(2)). Limitation or avoidance of progression to local critical ischemia requires control of atherosclerotic risk factors and proper foot care. The patient with arterial claudication needs to understand the local and general risks of arterial atherosclerotic disease, and to be involved in his/her own treatment. Obtaining patient compliance to medical care is fundamental: specific educational workshops are of great value for this.