Editor's Choice - 2017 ESC Guidelines on the Diagnosis and Treatment of Peripheral Arterial Diseases, in collaboration with the European Society for Vascular Surgery (ESVS)

18F-FDG Uptake on PET/CT in Symptomatic versus Asymptomatic Carotid Disease: a Meta-Analysis

INTRODUCTION

The role of positron emission tomography (PET)/computed tomography (CT) in the determination of inflammation in arterial disease is not well defined. This can provide information about arterial wall inflammation in atherosclerotic disease, and may give insight into plaque stability. The aim of this review was to perform a meta-analysis of PET/CT with ¹⁸F-FDG (fluorodeoxyglucose) uptake in symptomatic and asymptomatic carotid artery disease.

METHODS

This was a systematic review, following PRISMA guidelines, which interrogated the MEDLINE database from January 2001 to May 2017. The search combined the terms, "inflammation", "FDG", and "stroke". The search criteria included all types of studies, with a primary outcome of the degree of arterial vascular inflammation determined by ¹⁸F-FDG uptake. Analysis involved an inverse weighted variance estimate of pooled data, using a random effects model.

RESULTS

A total of 14 articles (539 patients) were included in the meta-analysis. Comparing carotid artery ¹⁸F-FDG uptake in symptomatic versus asymptomatic disease yielded a standard mean difference of 0.94 (95% CI 0.58-1.130; p < .0001; I² = 65%).

CONCLUSIONS

PET/CT using ¹⁸F-FDG can demonstrate carotid plaque inflammation, and is a marker of symptomatic disease. Further studies are required to understand the clinical implication of PET/CT as a risk prediction tool.

Hospital and Institutionalisation Care Costs after Limb and Visceral Ischaemia Benchmarked Against Stroke: Long-Term Results of a Population Based Cohort Study

OBJECTIVE/BACKGROUND

There are few published data on the acute care or long-term costs after acute/critical limb or visceral ischaemia (ACLVI) events. Using data from patients with acute events in a population based incidence study (Oxford Vascular Study), the present study aimed to determine the long-term costs after an ACLVI event.

METHODS

All patients with first ever incident ACLVI from 2002 to 2012 were included. Analysis was based on follow up until January 2017, with all patients having full 5 year follow up. Multivariate regressions were used to assess baseline and subsequent predictors of total 5 year hospital care costs. Overall costs after an ACLVI event were benchmarked against those after stroke in the same population, during the same period.

RESULTS

Among 351 patients with an ACLVI event, mean 5 year total care costs were €35,211 (SD 50,500), of which €6443 (18%) were due to long-term institutionalisation. Costs differed by type of event (acute visceral ischaemia €16,476; acute limb ischaemia €24,437; critical limb ischaemia €46,281; p < 0.001). Results of the multivariate analyses showed that patients with diabetes and those undergoing above knee amputations incurred additional costs of €11,804 (p = 0.014) and €25,692 (p < 0.001), respectively. Five year hospital care costs after an ACLVI event were significantly higher than after stroke (€28,768 vs. €22,623; p = 0.004), but similar after including long-term costs of institutionalisation (€35,211 vs. €35,391; p = 0.957).

CONCLUSION

Long-term care costs after an ACLVI event are considerable, especially after critical limb ischaemia. Hospital care costs were significantly higher than for stroke over the long term, and were similar after inclusion of costs of institutionalisation.

Clinical Effect and Cost-Effectiveness of Screening for Asymptomatic Carotid Stenosis: A Markov Model

OBJECTIVE/BACKGROUND

The cost-effectiveness of screening depends on the cost of screening, prevalence of asymptomatic carotid artery stenosis (ACAS), and the potential effect of medical intervention in reducing the risk of stroke. The aim of the study was to determine the threshold values for these parameters in order for screening for ACAS to be cost-effective.

METHODS

The clinical effect and cost-effectiveness of ultrasound screening for ACAS with subsequent initiation of preventive therapy versus not screening was assessed in a Markov model with a lifetime perspective. Key parameters, including stroke risk, all cause mortality, and costs, were based on contemporary published data, population statistics, and data from an ongoing screening program in Uppsala county (population 300,000), Sweden. Prevalence of ACAS (2%) and the rate of best medical treatment (BMT; 40%) were based on data from a male Swedish population recently screened for ACAS. The required stroke risk reduction from BMT, incremental cost-efficiency ratio (ICER), absolute risk reduction for stroke (ARR), and number needed to screen (NNS) were calculated.

RESULTS

Screening was cost-effective at an ICER of €5744 per incremental quality adjusted life year (QALY) gained. ARR was 135 per 100,000 screened, NNS was 741, and QALYs gained were 6700 per 100,000 invited. At a willingness to pay (WTP) threshold of €50,000 per QALY the minimum required stroke risk reduction from BMT was 22%. The assumed degree of stroke risk reduction was the most important determinant of cost-efficiency.

CONCLUSION

A moderate (22%) reduction in the risk of stroke was required for an ACAS screening strategy to be cost-effective at a WTP of €50,000/QALY. Targeting populations with a higher prevalence of ACAS could further improve cost-efficiency.

Supervised exercise therapy versus home-based exercise therapy versus walking advice for intermittent claudication

BACKGROUND

Although supervised exercise therapy (SET) provides significant symptomatic benefit for patients with intermittent claudication (IC), it remains an underutilized tool. Widespread implementation of SET is restricted by lack of facilities and funding. Structured home-based exercise therapy (HBET) with an observation component (e.g., exercise logbooks, pedometers) and just walking advice (WA) are alternatives to SET. This is the second update of a review first published in 2006.

OBJECTIVES

The primary objective was to provide an accurate overview of studies evaluating effects of SET programs, HBET programs, and WA on maximal treadmill walking distance or time (MWD/T) for patients with IC. Secondary objectives were to evaluate effects of SET, HBET, and WA on pain-free treadmill walking distance or time (PFWD/T), quality of life, and self-reported functional impairment.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register (December 16, 2016) and the Cochrane Central Register of Controlled Trials (2016, Issue 11). We searched the reference lists of relevant studies identified through searches for other potential trials. We applied no restriction on language of publication.

SELECTION CRITERIA

We included parallel-group randomized controlled trials comparing SET programs with HBET programs and WA in participants with IC. We excluded studies in which control groups did not receive exercise or walking advice (maintained normal physical activity). We also excluded studies comparing exercise with percutaneous transluminal angioplasty, bypass surgery, or drug therapy.

DATA COLLECTION AND ANALYSIS

Three review authors (DH, HF, and LG) independently selected trials, extracted data, and assessed trials for risk of bias. Two other review authors (MvdH and JT) confirmed the suitability and methodological quality of trials. For all continuous outcomes, we extracted the number of participants, mean outcome, and standard deviation for each treatment group through the follow-up period, if available. We extracted Medical Outcomes Study Short Form 36 outcomes to assess quality of life, and Walking Impairment Questionnaire outcomes to assess self-reported functional impairment. As investigators used different scales to present results of walking distance and time, we standardized reported data to effect sizes to enable calculation of an overall standardized mean difference (SMD). We obtained summary estimates for all outcome measures using a random-effects model. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

For this update, we included seven additional studies, making a total of 21 included studies, which involved a total of 1400 participants: 635 received SET, 320 received HBET, and 445 received WA. In general, SET and HBET programs consisted of three exercise sessions per week. Follow-up ranged from six weeks to two years. Most trials used a treadmill walking test to investigate effects of exercise therapy on walking capacity. However, two trials assessed only quality of life, functional impairment, and/or walking behavior (i.e., daily steps measured by pedometer). The overall methodological quality of included trials was moderate to good. However, some trials were small with respect to numbers of participants, ranging from 20 to 304.SET groups showed clear improvement in MWD/T compared with HBET and WA groups, with overall SMDs at three months of 0.37 (95% confidence interval [CI] 0.12 to 0.62; P = 0.004; moderate-quality evidence) and 0.80 (95% CI 0.53 to 1.07; P < 0.00001; high-quality evidence), respectively. This translates to differences in increased MWD of approximately 120 and 210 meters in favor of SET groups. Data show improvements for up to six and 12 months, respectively. The HBET group did not show improvement in MWD/T compared with the WA group (SMD 0.30, 95% CI -0.45 to 1.05; P = 0.43; moderate-quality evidence).Compared with HBET, SET was more beneficial for PFWD/T but had no effect on quality of life parameters nor on self-reported functional impairment. Compared with WA, SET was more beneficial for PFWD/T and self-reported functional impairment, as well as for some quality of life parameters (e.g., physical functioning, pain, and physical component summary after 12 months), and HBET had no effect.Data show no obvious effects on mortality rates. Thirteen of the 1400 participants died, but no deaths were related to exercise therapy. Overall, adherence to SET was approximately 80%, which was similar to that reported with HBET. Only limited adherence data were available for WA groups.

AUTHORS' CONCLUSIONS

Evidence of moderate and high quality shows that SET provides an important benefit for treadmill-measured walking distance (MWD and PFWD) compared with HBET and WA, respectively. Although its clinical relevance has not been definitively demonstrated, this benefit translates to increased MWD of 120 and 210 meters after three months in SET groups. These increased walking distances are likely to have a positive impact on the lives of patients with IC. Data provide no clear evidence of a difference between HBET and WA. Trials show no clear differences in quality of life parameters nor in self-reported functional impairment between SET and HBET. However, evidence is of low and very low quality, respectively. Investigators detected some improvements in quality of life favoring SET over WA, but analyses were limited by small numbers of studies and participants. Future studies should focus on disease-specific quality of life and other functional outcomes, such as walking behavior and physical activity, as well as on long-term follow-up.

Cost-Effectiveness Evaluation of Heparin Coated Versus Standard Graft for Bypass Surgery in Peripheral Artery Disease Alongside a Randomised Controlled Trial

OBJECTIVE/BACKGROUND

Heparin coating has recently been shown to reduce the risk of graft failure in arterial revascularisation, at least transiently. The aim of this study was to assess the cost-effectiveness of heparin coated versus standard polytetrafluoroethylene grafts for bypass surgery in peripheral artery disease from a long-term healthcare system perspective.

METHODS

Cost-effectiveness evaluation was conducted alongside the Danish part of the Scandinavian Propaten trial in which 431 patients planned for femoro-femoral or femoro-popliteal bypass surgery were randomised to either type of graft and followed for 5 years. Based on the intention to treat principle, the differences in healthcare costs (general practice, prescription medication, hospital admission, rehabilitation, and long-term care in 2015 Euros), life years (LYs), and quality adjusted life years (QALYs) were analysed as arithmetic means with bootstrapped 95% confidence intervals. Cost-effectiveness acceptability curves were used to illustrate the probability of cost-effectiveness for a range of threshold values of willingness to pay (WTP).

RESULTS

No statistically significant differences between the randomisation groups were observed for costs or gains of LYs or QALYs. The average cost per QALY was estimated at €10,792. For a WTP threshold of €40,000 per QALY, the overall probability of cost-effectiveness was estimated at 62%, but owing to cost savings in patients with critical ischaemia (cost per QALY <€0), it increased to 89% for this subgroup.

CONCLUSION

Until further evidence, heparin coated grafts appear overall, to be cost-effective over standard grafts, but important heterogeneity between claudication and critical ischaemia should be noted. While the optimal choice for claudication remains uncertain, heparin coated grafts should be used for critical ischaemia.

Carotid Artery Stenting

Carotid artery stenosis is relatively common and is a significant cause of ischemic stroke, but carotid revascularization can reduce the risk of ischemic stroke in patients with significant symptomatic stenosis. Carotid endarterectomy has been and remains the gold standard treatment to reduce the risk of carotid artery stenosis. Carotid artery stenting (CAS) (or carotid artery stent implantation) is another method of carotid revascularization, which has developed rapidly over the last 30 years. To date, the frequency of use of CAS is increasing, and clinical outcomes are improving with technical advancements. However, the value of CAS remains unclear in patients with significant carotid artery stenosis. This review article discusses the basic concepts and procedural techniques involved in CAS.

Predictors of Change in the Ankle Brachial Index with Exercise

OBJECTIVE

A 20% or greater decrease in the ankle brachial index (ABI) with exercise is suggestive of peripheral artery disease (PAD), and could identify patients with an increased mortality risk. The predictors of a change in the ABI with exercise have received little attention.

METHODS

This was a cross-sectional analysis. Two hundred and sixty five participants of the San Diego Population Study with a resting ABI between 0.90 and 1.10 performed 50 heel raises and immediately had their ABIs measured again. The relationship between the change in the ABI with exercise and multiple potential risk prediction variables were examined using linear regression. In addition, the categorical percent change in the ABI with exercise was analysed by multinomial logistic regression.

RESULTS

The mean age of participants was 71.8 years, and 80.4% were female. At rest, the average ABI was 1.04 (SD 0.04) before and 0.94 (SD 0.13) after exercise; a mean decrease of 9.5%. In analyses of ABI change as a continuous variable, higher age, any smoking history, and a diagnosis of chronic obstructive pulmonary disease (COPD) were associated with a significant decrease in the ABI with exercise (p = .01, .04, and .03, respectively). Categorical analyses of the risk factors associated with a 20% or greater ABI decrease with exercise confirmed these results. Congestive heart failure was associated with an increased ABI with exercise (p = .04) in continuous ABI change analyses only.

CONCLUSIONS

Older age, a positive history of smoking, and a history of COPD were independently and significantly associated with a greater ABI decrease with exercise. These risk variables may help identify persons with subclinical PAD.

Primary Prevention of Stroke in Chronic Kidney Disease Patients: A Scientific Update

BACKGROUND

Although chronic kidney disease (CKD) is an independent risk factor for stroke, official recommendations for the primary prevention of stroke in CKD are generally lacking.

SUMMARY

We searched PubMed and ISI Web of Science for randomised controlled trials, observational studies, reviews, meta-analyses and guidelines referring to measures of stroke prevention or to the treatment of stroke-associated risk factors (cardiovascular disease in general and atrial fibrillation (AF), arterial hypertension or carotid artery disease in particular) among the CKD population. The use of oral anticoagulation in AF appears safe in non-end stage CKD, but it should be individualized and preferably based on thromboembolic and bleeding stratification algorithms. Non-vitamin K antagonist oral anticoagulants with definite dose adjustment are generally preferred over vitamin K antagonists in mild and moderate CKD and their indications have started being extended to severe CKD and dialysis also. Aspirin, but not clopidogrel, has limited indications for reducing the risk for atherothrombotic events in CKD due to its increased bleeding risk. Carotid endarterectomy has shown promising results for stroke risk reduction in CKD patients with high-grade symptomatic carotid stenosis. The medical treatment of arterial hypertension in CKD often fails to efficiently lower blood pressure values, but recent data regarding the use of interventional procedures such as renal denervation, baroreflex activation therapy or renal artery stenting are encouraging. Key Messages: In the absence of clear guidelines and protocols, primary prevention of stroke in CKD patients remains a subtle art in the hands of the clinicians. Nevertheless, refraining CKD patients from standard therapies often worsens their prognosis.