Glucose intolerance, physical signs of peripheral artery disease, and risk of cardiovascular events: the Framingham Study

Tourniquet use for people with peripheral arterial disease undergoing major lower limb amputations

BACKGROUND

At least 7000 major lower limb amputations (MLLAs) are performed in the UK each year, 80% of which are due to peripheral arterial disease (PAD). Intraoperative blood loss can have a deleterious effect on patient outcomes, and its replacement with transfused blood is not without risk. Tourniquets can be used in lower limb surgical procedures to provide a bloodless surgical field, minimise intraoperative blood loss, and reduce perioperative blood transfusion requirements. Although their safety has been demonstrated in certain orthopaedic operations, their use among people with PAD undergoing MLLA remains controversial. Many clinicians are concerned about tourniquets potentially compromising perfusion of the stump and thereby impacting wound healing through direct tissue injury, damage to the arterial supply of the wound, or both.

OBJECTIVES

To assess the safety and effectiveness of tourniquet use in people undergoing MLLA for complications of PAD, specifically with regard to intraoperative blood loss, change in haemoglobin levels, transfusion rates, wound healing, need for revision surgery, and postoperative complications including mortality.

SEARCH METHODS

We searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers from inception to 17 May 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing tourniquet use to no tourniquet use among people with PAD undergoing MLLA.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were intraoperative blood loss, fall in haemoglobin levels, and perioperative blood transfusion requirement. Secondary outcomes were primary wound-healing rates, stump revision rates, other postoperative complications defined as per Clavien-Dindo classification, and postoperative mortality at 30 days and at maximal follow-up. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

One RCT met our inclusion criteria, which was a prospective randomised blinded controlled trial conducted in Sheffield, UK in 2006. In total 64 participants undergoing transtibial amputation for non-reconstructable PAD were randomised to either tourniquet or no tourniquet to assess for intraoperative blood loss, fall in haemoglobin, transfusion requirement, wound healing, stump breakdown and revision. Ten participants were excluded postrandomisation (five from the tourniquet group and five from the no tourniquet group). The reported median volume of intraoperative blood loss was significantly less in the tourniquet group (255 mL (interquartile range (IQR) 150 to 572.5 mL))) compared to the control group (550 mL (IQR 255 to 1050 mL)) (P = 0.014). There was a significantly lower median drop in haemoglobin concentration in the tourniquet group (1.0 g/dL (IQR 0.6 to 2.4 g/dL)) compared to the control group (1.8 g/dL (IRQ 0 to 1.2 g/dL)) (P = 0.035). There was a significantly lower perioperative blood transfusion requirement in the tourniquet group (8 participants, 32%) compared to the control group (14 participants, 48%) (P = 0.047). There were no clear differences in wound breakdown, stump revision, primary wound healing at six weeks, postoperative complications (myocardial infarction, cardiac arrhythmias, pulmonary oedema), and death between groups. We assessed the one included study as at low risk of bias for sequence generation and blinding of outcome assessors; high risk of bias for incomplete outcome data and selective outcome reporting; and unclear risk of bias for allocation concealment, blinding of participants and personnel, and other sources of bias. We assessed the certainty of the evidence as low or very low due to risk of bias, small sample size, and the study being insufficiently powered for most outcomes.

AUTHORS' CONCLUSIONS

This review identified only one small historical RCT evaluating tourniquet use in MLLA. Tourniquets appeared to reduce intraoperative blood loss, drop in haemoglobin, and blood transfusion requirements following transtibial amputations for people with PAD. However, it is unclear whether tourniquets affect wound healing, stump revision rates, postoperative complications, or mortality. High-certainty evidence is required to inform clinical decision-making for the use of tourniquets in these patients.

Peripheral artery disease in outpatients with a recent history of acute coronary syndrome or at high atherothrombotic risk

OBJECTIVES

The frequency and implications of peripheral artery disease (PAD) in some risk groups are not entirely characterized in Latin America. We studied PAD prevalence, risk factors, and six-month outcomes in stable outpatients with a history of a recent acute coronary syndrome (ACS), or at high coronary risk.

METHODS

We recruited 830 outpatients in 43 Mexican sites (median age: 64.8 years; 57.8% men). Inclusion criteria were age >18 years, and ACS within 30 days, or age <55 years plus ≥2 major vascular risk factors, or age ≥55 years plus ≥1 vascular risk factors. Patients received standardized assessments at baseline and six-month follow-up for medical history, ankle-brachial index (ABI), and the Edinburgh Claudication Questionnaire (ECQ).

RESULTS

ABI <0.8 was found in 10.5%, <0.9 in 22.5%, >1.3 in 4.8%, and >1.4 in 3.6%, without differences according to sex or selection criteria. Positive ECQ was found in 7.6%. ABI <0.9 was directly associated with age, diabetes, ACS, and chronic kidney disease, but inversely associated with BMI >27. The six-month case-fatality and atherothrombotic events rates were 1.6% and 3.6%, respectively. In patients with ABI <0.9 and ABI <0.8, the six-month case-fatality rates were 2.5% (p = 0.27) and 5.4% (p = 0.03), respectively. In a Cox proportional-hazards model, baseline factors associated with death were age ≥65, ABI <0.8, and ACS.

CONCLUSIONS

Subclinical PAD is more common than symptomatic claudication in high-risk coronary outpatients. Low ABI is associated with reduced short-term survival in patients with recent ACS or at high coronary risk.

Podiatry Ankle Duplex Scan: Readily Learned and Accurate in Diabetes

We aimed to train podiatrists to perform a focused duplex ultrasound scan (DUS) of the tibial vessels at the ankle in diabetic patients; podiatry ankle (PodAnk) duplex scan. Thirteen podiatrists underwent an intensive 3-hour long simulation training session. Participants were then assessed performing bilateral PodAnk duplex scans of 3 diabetic patients with peripheral arterial disease. Participants were assessed using the duplex ultrasound objective structured assessment of technical skills (DUOSATS) tool and an "Imaging Score". A total of 156 vessel assessments were performed. All patients had abnormal waveforms with a loss of triphasic flow. Loss of triphasic flow was accurately detected in 145 (92.9%) vessels; the correct waveform was identified in 139 (89.1%) cases. Participants achieved excellent DUOSATS scores (median 24 [interquartile range: 23-25], max attainable score of 26) as well as "Imaging Scores" (8 [8-8], max attainable score of 8) indicating proficiency in technical skills. The mean time taken for each bilateral ankle assessment was 20.4 minutes (standard deviation ±6.7). We have demonstrated that a focused DUS for the purpose of vascular assessment of the diabetic foot is readily learned using intensive simulation training.

Review: Insulin-like growth factor-related proteins and diabetic complications

The insulin-like growth factor system and, in particular, insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-1 (IGFBP-1) are dysregulated in type 1 and type 2 diabetes. Serum IGF-I levels are low in both forms of diabetes, and this may be in part genetically determined. It is possible that the reduced serum levels of IGF-I are involved in the development of microvascular and macrovascular complications. Fasting serum IGFBP-1 levels are usually low in early type 2 diabetic patients with insulin resistance and hyperinsulinaemia but may be raised in patients with particularly poor glycaemic control and severe beta-cell failure. Treatment with IGF-I/binding protein complexes has been shown to improve glycaemic control in conjunction with insulin and may in future have a place in the treatment of diabetes, potentially to prevent diabetic complications. Serum IGFBP-1 determination may have utility in the assessment of cardiovascular risk and as an indicator for insulin resistance.

Performance of prognostic markers in the prediction of wound healing or amputation among patients with foot ulcers in diabetes: a systematic review

Prediction of wound healing and major amputation in patients with diabetic foot ulceration is clinically important to stratify risk and target interventions for limb salvage. No consensus exists as to which measure of peripheral artery disease (PAD) can best predict outcomes. To evaluate the prognostic utility of index PAD measures for the prediction of healing and/or major amputation among patients with active diabetic foot ulceration, two reviewers independently screened potential studies for inclusion. Two further reviewers independently extracted study data and performed an assessment of methodological quality using the Quality in Prognostic Studies instrument. Of 9476 citations reviewed, 11 studies reporting on 9 markers of PAD met the inclusion criteria. Annualized healing rates varied from 18% to 61%; corresponding major amputation rates varied from 3% to 19%. Among 10 studies, skin perfusion pressure ≥ 40 mmHg, toe pressure ≥ 30 mmHg (and ≥ 45 mmHg) and transcutaneous pressure of oxygen (TcPO2 ) ≥ 25 mmHg were associated with at least a 25% higher chance of healing. Four studies evaluated PAD measures for predicting major amputation. Ankle pressure < 70 mmHg and fluorescein toe slope < 18 units each increased the likelihood of major amputation by around 25%. The combined test of ankle pressure < 50 mmHg or an ankle brachial index (ABI) < 0.5 increased the likelihood of major amputation by approximately 40%. Among patients with diabetic foot ulceration, the measurement of skin perfusion pressures, toe pressures and TcPO2 appear to be more useful in predicting ulcer healing than ankle pressures or the ABI. Conversely, an ankle pressure of < 50 mmHg or an ABI < 0.5 is associated with a significant increase in the incidence of major amputation.

Effectiveness of bedside investigations to diagnose peripheral artery disease among people with diabetes mellitus: a systematic review

Non-invasive tests for the detection of peripheral artery disease (PAD) among individuals with diabetes mellitus are important to estimate the risk of amputation, ulceration, wound healing and the presence of cardiovascular disease, yet there are no consensus recommendations to support a particular diagnostic modality over another and to evaluate the performance of index non-invasive diagnostic tests against reference standard imaging techniques (magnetic resonance angiography, computed tomography angiography, digital subtraction angiography and colour duplex ultrasound) for the detection of PAD among patients with diabetes. Two reviewers independently screened potential studies for inclusion and extracted study data. Eligible studies evaluated an index test for PAD against a reference test. An assessment of methodological quality was performed using the quality assessment for diagnostic accuracy studies instrument. Of the 6629 studies identified, ten met the criteria for inclusion. In these studies, the patients had a median age of 60-74 years and a median duration of diabetes of 9-24 years. Two studies reported exclusively on patients with symptomatic (ulcerated/infected) feet, two on patients with asymptomatic (intact) feet only, and the remaining six on patients both with and without foot ulceration. Ankle brachial index (ABI) was the most widely assessed index test. Overall, the positive likelihood ratio and negative likelihood ratio (NLR) of an ABI threshold <0.9 ranged from 2 to 25 (median 8) and <0.1 to 0.7 (median 0.3), respectively. In patients with neuropathy, the NLR of the ABI was generally higher (two out of three studies), indicating poorer performance, and ranged between 0.3 and 0.5. A toe brachial index <0.75 was associated with a median positive likelihood ratio and NLRs of 3 and ≤ 0.1, respectively, and was less affected by neuropathy in one study. Also, in two separate studies, pulse oximetry used to measure the oxygen saturation of peripheral blood and Doppler wave form analyses had NLRs of 0.2 and <0.1. The reported performance of ABI for the diagnosis of PAD in patients with diabetes mellitus is variable and is adversely affected by the presence of neuropathy. Limited evidence suggests that toe brachial index, pulse oximetry and wave form analysis may be superior to ABI for diagnosing PAD in patients with neuropathy with and without foot ulcers. There were insufficient data to support the adoption of one particular diagnostic modality over another and no comparisons existed with clinical examination. The quality of studies evaluating diagnostic techniques for the detection of PAD in individuals with diabetes is poor. Improved compliance with guidelines for methodological quality is needed in future studies.

Diagnosis and assessment of peripheral arterial disease in the diabetic foot

Approximately half of all patients with a diabetic foot ulcer have co-existing peripheral arterial disease. Identifying peripheral arterial disease among patients with foot ulceration is important, given its association with failure to heal, amputation, cardiovascular events and increased risk of premature mortality. Infection, oedema and neuropathy, often present with ulceration, may adversely affect the performance of diagnostic tests that are reliable in patients without diabetes. Early recognition and expert assessment of peripheral arterial disease allows measures to be taken to reduce the risk of amputation and cardiovascular events, while determining the need for revascularization to promote ulcer healing. When peripheral arterial disease is diagnosed, the extent of perfusion deficit should be measured. Patients with a severe perfusion deficit, likely to affect ulcer healing, will require further imaging to define the anatomy of disease and indicate whether a revascularization procedure is appropriate.

Clues to Cardiovascular Risk: An Office-Based Approach

Current tools for predicting coronary heart disease risk in the asymptomatic patient fall into 2 major categories: traditional population-based models and noninvasive imaging techniques. Population-based models that estimate cardiovascular risk are powerful clinical tools but do not utilize a large volume of patient-specific data that are readily available to the clinician and may help to identify at-risk patients. The use of high-technology noninvasive imaging has not been consistently validated and clinicians or patients often lack the resources for such testing. This paper reviews several commonly encountered historical, physical, radiologic, laboratory, and electrocardiographic markers of increased cardiovascular risk that may enhance clinicians' ability to identify individual patients at increased risk for coronary heart disease.

Safety and efficacy of reoperative carotid endarterectomy: A 14-year experience

BACKGROUND

Reoperative carotid endarterectomy (CEA) is an accepted treatment for recurrent carotid stenosis. With reports of a higher operative morbidity than primary CEA and the advent of carotid stenting, catheter-based therapy has been advocated as the primary treatment for this reportedly "high-risk" subgroup. This study reviews a contemporary experience with reoperative CEA to validate the high-risk categorization of these patients.

METHODS

From 1989 to 2002, 153 consecutive, isolated (excluding CEA/coronary artery bypass graft and carotid bypass operations) reoperative CEA procedures were reviewed. Clinical and demographic variables potentially associated with the end points of perioperative morbidity, long-term durability, and late survival were assessed with multivariate analysis.

RESULTS

There were 153 reoperative CEA procedures in 145 patients (56% men, 36% symptomatic) with an average age of 69 +/- 1.3 years. The average time from primary CEA (68% primary closure, 23% prosthetic, 9% vein patch) to reoperative CEA was 6.1 +/- 0.4 years (range, 0.3 to 20.4 years). At reoperation, patch reconstruction was undertaken in 93% of cases. The perioperative stroke rate was 1.9%, with no deaths or cardiac complications. Other complications included cranial nerve injury (1.3%) and hematoma (3.2%). Average follow-up after reoperative CEA was 4.4 +/- 0.3 years (range, 0.1 to 12.7 years), with an overall total stroke-free rate of 96% and a restenosis rate (>50%) by carotid duplex of 9.2%. Among variables assessed for association with restenosis after reoperative CEA, only younger age was found to be significant (66 +/- 2.5 years vs 70 +/- 0.7 years, P < .05). The all-cause long-term mortality rate was 29%. Multivariate analysis of long-term survival identified diabetes mellitus as having a negative impact (hazard ratio, 3.4 +/- 0.3, P < .05) and lipid-lowering agents as having a protective effect (hazard ratio, 0.42 +/- 0.4, P < .05) on survival.

CONCLUSION

Reoperative CEA is a safe and durable procedure, comparable to reported standards for primary CEA, for long-term protection from stroke. These data do not support the contention that patients who require reoperative CEA constitute a "high-risk" subgroup in whom reoperative therapy should be avoided.

Preoperative cardiac evaluation does not improve or predict perioperative or late survival in asymptomatic diabetic patients undergoing elective infrainguinal arterial reconstruction

OBJECTIVE

Patients undergoing infrainguinal arterial reconstruction frequently have increased cardiac risk factors. Diabetic patients are often asymptomatic despite advanced cardiac disease. This study investigates whether preoperative cardiac testing improves the outcome in diabetic patients at risk for cardiac disease.

METHODS

We retrospectively reviewed all patients undergoing lower-extremity arterial reconstructions in a 32-month period from July 1999 to February 2002. Of the 433 patients identified undergoing 539 procedures, 295 had diabetes mellitus and considered in this study. The patients were stratified into two groups according to the present American College of Cardiology, American Heart Association (ACC/AHA) algorithm. We identified 140 patients with two or more of ACC (Eagle) criteria who met the inclusion criteria for a preoperative cardiac evaluation. These patients were separated into two groups: those undergoing a cardiac work-up (WU) according to the ACC/AHA algorithm and those not undergoing the recommended work-up (NWU). Outcomes included perioperative mortality, postoperative myocardial infarction, congestive heart failure, arrhythmia, and length of hospitalization. Significance of association was assessed by the Fisher exact test. Length of hospitalization was compared using the Kruskal-Wallis rank sum test. Survival data was analyzed with the Kaplan-Meier method.

RESULTS

One hundred forty patients met the criteria for moderate risk. There were 61 patients in the NWU group and 79 in the WU group. Ten patients in the WU group underwent preoperative coronary revascularization (6 had percutaneous transluminal coronary angioplasty, 4 underwent coronary artery bypass grafting). There was no difference between perioperative mortality (WU, 1%; NWU, 2%; P = 1.00) or in postoperative cardiac morbidity, including myocardial infarction, congestive heart failure, and arrhythmia requiring treatment (WU, 5%; NWU, 6%; P = .71). There were no perioperative deaths and one episode of congestive heart failure in the group that had preoperative coronary revascularization. Median length of hospitalization was 10 days in the WU group and 8 days in the NWU group ( P = .11). Patient survival at 12 months for the NWU, WU, and revascularized groups was 85.3%, 78.5%, and 80.0%, respectively; 36-month survival was 73.6%, 62.9%, and 80.0%, respectively. The three survival curves did not differ significantly ( P = .209).

CONCLUSIONS

Preoperative cardiac evaluation, as defined by the ACC/AHA algorithm, does not predict or improve postoperative morbidity, mortality, or 36-month survival in asymptomatic, diabetic patients undergoing elective lower-extremity arterial reconstruction. These data do not support the current ACC/AHA recommendations as a standard of care for diabetic patients with an intermediate clinical predictor who undergo peripheral arterial reconstruction, a high-risk surgical procedure.

Diabetic dyslipidemia and exercise affect coronary tone and differential regulation of conduit and microvessel K+ current

Spontaneous transient outward K(+) currents (STOCs) elicited by Ca(2+) sparks and steady-state K(+) currents modulate vascular reactivity, but effects of artery size, diabetic dyslipidemia, and exercise on these differentially regulated K(+) currents are unclear. We studied the conduit arteries and microvessels of male Yucatan swine assigned to one of three groups for 20 wk: control (C, n = 7), diabetic dyslipidemic (DD, n = 6), or treadmill-trained DD animals (DDX, n = 7). Circumflex artery blood flow velocity obtained with intracoronary Doppler and lumen diameters obtained by intravascular ultrasound enabled calculation of absolute coronary blood flow (CBF). Ca(2+) sparks were determined in pressurized microvessels, and perforated patch clamp assessed K(+) current in smooth muscle cells isolated from conduits and microvessels. Baseline CBF in DD was decreased versus C. In pressurized microvessels, Ca(2+) spark activity was significantly lower in DD versus C and DDX (P < 0.05 vs. DDX). STOCs were pronounced in microvessel (approximately 35 STOCs/min) in sharp contrast to conduit cells ( approximately 2 STOCs/min). STOCs were decreased by 86% in DD versus C and DDX in microvessels; in contrast, there was no difference in STOCs across groups in conduit cells. Steady-state K(+) current in microvessels was decreased in DD and DDX versus C; in contrast, steady-state K(+) current in conduit cells was decreased in DDX versus DD and C. We conclude that steady-state K(+) current and STOCs are differentially regulated in conduit versus microvessels in health and diabetic dyslipidemia. Exercise prevented diabetic dyslipidemia-induced decreases in baseline CBF, possibly via STOC-regulated basal microvascular tone.

Statin therapy for the treatment of diabetic dyslipidemia

The increasing prevalence of type 2 diabetes is a major problem for healthcare providers globally, since it is associated with serious microvascular and macrovascular complications. Although microvascular complications can be largely reduced with strict glycemic control, prevention of macrovascular disease involves a multifaceted approach that addresses all major risk factors, including dyslipidemia, hypertension, and insulin insensitivity. In particular, the treatment of diabetic dyslipidemia is a major challenge for diabetologists and cardiologists, as it is characterized by an array of lipid abnormalities. The management of diabetic dyslipidemia should initially include lifestyle approaches such as improved nutrition and weight reduction; however, the majority of patients require the addition of pharmacotherapy. Whilst insulin and/or oral hypoglycemic drugs are generally prescribed for the treatment of hyperglycemia, the addition of lipid-lowering drugs may be necessary for the control of diabetic dyslipidemia. The American Diabetes Association guidelines recommend lowering of low-density lipoprotein cholesterol (LDL-C) as a first priority. Hydroxy-methylglutaryl coenzyme A reductase inhibitors (statins) are recommended for first-line therapy in diabetic patients, since these agents are effective at reducing LDL-C levels. Whilst statins provide effective control of dyslipidemia in the majority of patients, more efficacious treatment regimens would provide greater benefit to more patients. Combination therapies may provide one solution to obtaining maximal lipid profile modifications, although the introduction of new, more efficacious agents for use as monotherapy may provide a more acceptable option, as drug combinations are often associated with poor tolerability and patient compliance.

The platelet in diabetes: focus on prevention of ischemic events

Accelerated atherosclerosis and the increased risk of thrombotic vascular events in diabetes may result from dyslipidemia, endothelial dysfunction, platelet hyperreactivity, an impaired fibrinolytic balance, and abnormal blood flow. There is also a correlation between hyperglycemia and cardiovascular (CV) events. The importance of platelets in the atherothrombotic process has led to investigation of using antiplatelet agents to reduce CV risk. A meta-analysis conducted by the Antiplatelet Trialists' Collaboration demonstrated that aspirin reduced the risk of ischemic vascular events as a secondary prevention strategy in numerous high-risk groups, including patients with diabetes. Based on results from placebo-controlled randomized trials, the American Diabetes Association recommends low-dose enteric-coated aspirin as a primary prevention strategy for people with diabetes at high risk for CV events. Clopidogrel is recommended if aspirin allergy is present. There is occasionally a need for an alternative to aspirin or for additive antiplatelet therapy. Aspirin in low doses inhibits thromboxane production by platelets but has little to no effect on other sites of platelet reactivity. Agents such as ticlopidine and clopidogrel inhibit ADP-induced platelet activation, whereas the platelet glycoprotein (Gp) IIb/IIIa complex receptor antagonists block activity at the fibrinogen binding site on the platelet. These agents appear to be useful in acute coronary syndromes (ACSs) in diabetic and nondiabetic patients. A combination of clopidogrel plus aspirin was more effective than placebo plus standard therapy (including aspirin) in reducing a composite CV outcome in patients with unstable angina and non-ST segment elevation myocardial infarction. In a meta-analysis of six trials in diabetic patients with ACSs, intravenous GpIIb-IIIa inhibitors reduced 30-day mortality when compared with control subjects. Results from controlled prospective clinical trials justify the use of enteric-coated low-dose aspirin (81-325 mg) as a primary or secondary prevention strategy in adult diabetic individuals (aged >30 years) at high risk for CV events. Recent studies support the use of clopidogrel in addition to standard therapy, as well as the use of GpIIb-IIIa inhibitors in ACS patients.

Fasting plasma glucose is an independent determinant of left ventricular diastolic dysfunction in nondiabetic patients with treated essential hypertension

Left ventricular (LV) hypertrophy and LV diastolic dysfunction are common cardiac changes in hypertensive patients, and these changes are modified by various factors other than blood pressure. The present study was conducted to investigate the influence of mild abnormalities in glucose metabolism on LV structure and function in essential hypertension. In 193 nondiabetic patients with treated essential hypertension, two-dimensional and Doppler echocardiographic examinations were performed, and relative wall thickness (RWT), LV mass index (LVMI), fractional shortening, and the ratio of the peak velocity of atrial filling to early diastolic filling (A/E) were calculated. Fasting plasma glucose (FPG) and HbA1c levels were positively correlated with the A/E ratio and the deceleration time of the E wave. However, these plasma levels had no correlation with RWT, LVMI, or fractional shortening. Peak A wave velocity and the A/E ratio were significantly higher in patients who had FPG of > or = 100 mg/dl (and <126 mg/dl) than those who had FPG of <100 mg/dl, although age, blood pressure, RWT, LVMI, and fractional shortening did not differ between the two groups. In a multiple regression analysis of all subjects, only FPG and age were independent determinants of the A/E ratio. These observations suggest that FPG is a sensitive predictor for LV diastolic dysfunction in nondiabetic patients with treated hypertension. Since a slight increase in plasma glucose levels is associated with abnormalities in diastolic function independent of LV hypertrophy, an early stage of impaired glucose metabolism in hypertensive patients may specifically deteriorate cardiac diastolic function.

Preventing atherothrombotic events in peripheral arterial disease: the use of antiplatelet therapy

Patients with peripheral arterial disease (PAD) are at increased risk of generalized atherothrombotic events. Epidemiologic data shows a high rate of co-prevalence of PAD and atherosclerosis in other vascular beds. Aggressive risk-factor modification and antiplatelet therapy has become the cornerstone of treatment to prevent ischaemic events associated with PAD. Recent clinical trials have confirmed the clinical benefit of clopidogrel and ticlopidine in patients with PAD, agents that irreversibly inhibit the binding of adenosine diphosphate to its platelet receptor. In the clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE) trial, clopidogrel was associated with an overall risk reduction of 8.7% (compared with aspirin, P=0.043) in myocardial infarction (MI), ischaemic stroke and vascular death. These results demonstrated that long-term administration of clopidogrel was effective in preventing ischaemic events in patients with atherosclerotic vascular disease including PAD. Aspirin and/or clopidogrel are the antiplatelet agents of choice for the reduction of atherothrombotic events in patients with PAD.

Current practice and future promise for clinical noninvasive measurements of subclinical atherosclerotic disease in the elderly

The detection, treatment, and follow-up of subclinical vascular disease are becoming clinically essential components of cardiovascular disease prevention in the elderly. Noninvasive measurements are available for different vascular beds, including carotid, coronary, aortic, and peripheral arterial circulation. Current interest in these measures is aimed at improving the accuracy of risk prediction for coronary heart disease and cardiovascular disease. Indirect physical examination and imaging evaluations detect significant obstruction of flow in the peripheral arteries. Doppler measures of ankle-arm blood pressure index represent a simple, indirect test that has been shown to be predictive of incident cardiovascular disease independent of risk factors. Newer, high-resolution tests allow direct detection and quantitation of the burden of atherosclerosis and vascular disease within the arterial wall, independent of flow obstruction. Carotid intimal-medial thickness predicts incident coronary heart disease and stroke in the elderly, even after adjustment for traditional risk factors. Coronary calcium can be accurately detected by computed tomography and is a strong predictor of the incidence of coronary heart disease events. Evidence is accruing that coronary calcium screening will play a role in prevention in the elderly. Magnetic resonance imaging is currently under study as a promising modality for detection and quantification of aortic and carotid plaque. Ongoing studies will provide important information regarding the appropriate role of the many newer, high-resolution tests of subclinical atherosclerosis in disease prediction, treatment, and tracking of disease progression in the elderly.

Impaired glucose tolerance as a disease

Current criteria for diagnosing diabetes, based on fasting plasma glucose levels during administration of the oral glucose tolerance test (OGTT), are poorly sensitive and are only modestly predictive of microvascular risk. The period after administration of OGTT is far more predictive and more closely resembles the postprandial state where microvascular risk is elevated. However, persons who do not yet exhibit symptoms of diabetes may nonetheless have impaired glucose tolerance or dysglycemia, whereby macrovascular disease can develop at a glucose level lower than the threshold for microvascular disease and can progress in a graded fashion. This article reviews the factors that may cause dysglycemia (including insulin resistance and obesity) and how diet, blood pressure control, and the use of statins or glycemic/insulin sensitizing may reduce cardiovascular risk in this prediabetic population.