P6: ANTIPLATELET AND ANTICOAGULANT USE IN RANDOMISED TRIALS OF PATIENTS UNDERGOING ENDOVASCULAR INTERVENTION FOR PERIPHERAL ARTERIAL DISEASE: SYSTEMATIC REVIEW

Introduction

Guideline recommendations for antithrombotic (antiplatelet and anticoagulant) therapy during and after endovascular intervention are patchy and conflicted, in part due to a lack of evidence. The aim of this systematic review was to examine the antithrombotic specifications in randomised trials for peripheral arterial endovascular intervention.

Method

This review was conducted according to PRISMA guidelines. Randomised trials including participants with peripheral arterial disease undergoing endovascular arterial intervention were included. Trial methods were assessed to determine whether an antithrombotic protocol had been specified, its completeness, and the agent(s) prescribed. Antithrombotic protocols were classed as periprocedural (preceding/during intervention), immediate postprocedural (up to 14 days following intervention) and maintenance postprocedural (therapy continuing beyond 14 days). Trials were stratified according to type of intervention.

Result

Ninety-four trials were included. Only 29% of trials had complete periprocedural antithrombotic protocols, and 34% had complete post-procedural protocols. In total, 64 different periprocedural protocols, and 51 separate postprocedural protocols were specified.

Antiplatelet monotherapy and unfractionated heparin were the most common choices of regimen in the periprocedural setting, and dual antiplatelet therapy (55%) was most commonly utilised postprocedure. There is an increasing tendency to use dual antiplatelet therapy with time or for drug-coated technologies.

Conclusion

Randomised trials comparing different types of peripheral endovascular arterial intervention have a high level of heterogeneity in their antithrombotic regimens, and there has been an increasing tendency to use dual antiplatelet therapy over time. Antiplatelet regimes need to be standardised in trials comparing endovascular technologies.

Take-home message

To determine the benefits of any endovascular intervention within a randomised trial, antithrombotic regimens should be standardised to prevent confounding. This systematic review demonstrates a high level of heterogeneity of antithrombotic prescribing in randomised trials of endovascular intervention, and an increasing tendency to utilise dual antiplatelet therapy, despite a lack of evidence of benefit, but an increased risk of harm.

Umbrella review and meta-analysis of antiplatelet therapy for peripheral artery disease

Background

The literature on antiplatelet therapy for peripheral artery disease has historically been summarized inconsistently, leading to conflict between international guidelines. An umbrella review and meta-analysis was performed to summarize the literature, allow assessment of competing safety risks and clinical benefits, and identify weak areas for future research.

Methods

MEDLINE, Embase, DARE, PROSPERO and Cochrane databases were searched from inception until January 2019. All meta-analyses of antiplatelet therapy in peripheral artery disease were included. Quality was assessed using AMSTAR scores, and GRADE analysis was used to quantify the strength of evidence. Data were pooled using random-effects models.

Results

Twenty-eight meta-analyses were included. Thirty-three clinical outcomes and 41 antiplatelet comparisons in 72 181 patients were analysed. High-quality evidence showed that antiplatelet monotherapy reduced non-fatal strokes (3 (95 per cent c.i. 0 to 6) fewer per 1000 patients), In symptomatic patients, it reduced cardiovascular deaths (8 (0 to 16) fewer per 1000 patients), but increased the risk of major bleeding (7 (3 to 14) more events per 1000). In asymptomatic patients, monotherapy reduced non-fatal strokes (5 (0 to 8) fewer per 1000), but had no other clinical benefit. Dual antiplatelet therapy caused more major bleeding after intervention than monotherapy (37 (8 to 102) more events per 1000), with very low-quality evidence of improved endovascular patency (risk ratio 4·00, 95 per cent c.i. 0·91 to 17·68).

Conclusion

Antiplatelet monotherapy has minimal clinical benefit for asymptomatic peripheral artery disease, and limited benefit for symptomatic disease, with a clear risk of major bleeding. There is a lack of evidence to guide antiplatelet prescribing after peripheral endovascular intervention.

Angiosome Specific Revascularisation: Does the Evidence Support It?

OBJECTIVE

To explain the angiosome concept and explore the practical application of the angiosome literature to a clinical scenario, in this case a tibial angioplasty for critical ischaemia.

METHODS

Clinical vignette with explanation of the decisions made and subsequent clinical results based on the theory of the angiosome concept and the literature on angiosomal revascularisation; in this case the results of our group's recent update to a systematic review and meta-analysis.

RESULTS

Endovascular combined or direct angiosomal revascularisation if superior to indirect revascularisation. This was borne out in the clinical scenario, where an indirect peroneal reperfusion of the AT angiosome resulted in major amputation. Open surgery is less dependent on the angiosome concept. The presence of adequate collateralisation into a foot arch seems to be the most important factor predicting success of indirect revascularisation. The evidence for both suffers from selection bias and many of the findings in the literature are wholly due to selection bias.

CONCLUSION

The angiosome concept is useful during both open and endovascular tibial revascularisation. However, the runoff in the foot is critical to success and may not follow the 'classic' angiosome model in diabetes.

Weekend effect in non-elective abdominal aortic aneurysm repair

Background

The ‘weekend effect’ describes the phenomenon where patient outcomes appear worse for those admitted at the weekend. It has been used recently to justify significant changes in UK health policy. Recent evidence has suggested that the effect may be due to a combination of inadequate correction for confounding factors and inaccurate coding. The effects of these factors were investigated in patients with acute abdominal aortic aneurysm (AAA).

Methods

Patients undergoing non‐elective AAA repair entered into the UK National Vascular Registry from January 2013 until December 2015 were included in a case–control study. The patients were divided according to whether they were treated during the week (Monday 08.00 hours to Friday 17.00 hours) or at the weekend. Data extracted included demographics, co‐morbidities, preoperative medications and baseline blood test results, as well as outcomes. Coding issues were investigated by looking at patients treated for ruptured, symptomatic or asymptomatic AAA within the non‐elective cohort. The primary outcome was in‐hospital mortality. Secondary outcomes included length of inpatient stay, and cardiac, respiratory and renal complications.

Results

The mortality rate appeared to be higher at the weekend (odds ratio (OR) 1·69, 95 per cent c.i. 1·47 to 1·94; P < 0·001), but this effect disappeared when confounding factors and coding issues were corrected for (corrected OR for ruptured AAA 1·09, 0·92 to 1·29; P = 0·330). Differences in outcomes were similar for prolonged length of hospital stay (uncorrected OR 1·21, 95 per cent c.i. 1·06 to 1·37, P = 0·005; corrected OR for ruptured AAA 1·06, 0·91 to 1·10, P = 0·478), and morbidity outcomes.

Conclusion

After appropriate correction for confounding factors and coding effects, there was no evidence of a significant weekend effect in the treatment of non‐elective AAA in the UK.

Infrapopliteal angioplasty using a combined angiosomal reperfusion strategy

Introduction

Infra-popliteal angioplasty continues to be widely performed with minimal evidence to guide practice. Endovascular device selection is contentious and there is even uncertainty over which artery to treat for optimum reperfusion. Direct reperfusion (DR) targets the artery supplying the ischaemic tissue. Indirect reperfusion (IR) targets an artery supplying collaterals to the ischaemic area. Our unit practice for the last eight years has been to attempt to open all tibial arteries at the time of angioplasty. When successful, this results in both direct and indirect; or combined reperfusion (CR). The aim was to review the outcomes of CR and compare them with DR or IR alone.

Methods

An eight year retrospective review from a single unit of all infra-popliteal angioplasties was undertaken. Wound healing, limb salvage, amputation-free and overall survival data as well as re-intervention rates were captured for all patients. Subgroup analysis for diabetics was undertaken. Kaplan Meier curves are presented for survival outcomes. All odds and hazard ratios (HR) and p values were corrected for bias from confounders using multivariate analysis.

Results

250 procedures were performed: 22 (9%) were CR; 115 (46%) DR and 113 (45%) IR. Amputation-free survival (HR 0.504, p = 0.039) and re-intervention and amputation-free survival (HR 0.414, p = 0.005) were significantly improved in patients undergoing CR compared to IR. Wound healing was similarly affected by reperfusion strategy (OR = 0.35, p = 0.047). Effects of CR over IR were similar when only diabetic patients were considered.

Conclusions

Combined revascularisation can only be achieved in approximately 10% of patients. However, when successful, it results in significant improvements in wound healing and amputation-free survival over simple indirect reperfusion techniques.

Mild cold effects on hunger, food intake, satiety and skin temperature in humans

BACKGROUND

Mild cold exposure increases energy expenditure and can influence energy balance, but at the same time it does not increase appetite and energy intake.

OBJECTIVE

To quantify dermal insulative cold response, we assessed thermal comfort and skin temperatures changes by infrared thermography.

METHODS

We exposed healthy volunteers to either a single episode of environmental mild cold or thermoneutrality. We measured hunger sensation and actual free food intake. After a thermoneutral overnight stay, five males and five females were exposed to either 18°C (mild cold) or 24°C (thermoneutrality) for 2.5 h. Metabolic rate, vital signs, skin temperature, blood biochemistry, cold and hunger scores were measured at baseline and for every 30 min during the temperature intervention. This was followed by an ad libitum meal to obtain the actual desired energy intake after cold exposure.

RESULTS

We could replicate the cold-induced increase in REE. But no differences were detected in hunger, food intake, or satiety after mild cold exposure compared with thermoneutrality. After long-term cold exposure, high cold sensation scores were reported, which were negatively correlated with thermogenesis. Skin temperature in the sternal area was tightly correlated with the increase in energy expenditure.

CONCLUSIONS

It is concluded that short-term mild cold exposure increases energy expenditure without changes in food intake. Mild cold exposure resulted in significant thermal discomfort, which was negatively correlated with the increase in energy expenditure. Moreover, there is a great between-subject variability in cold response. These data provide further insights on cold exposure as an anti-obesity measure.

Effect of frailty on short- and mid-term outcomes in vascular surgical patients

BACKGROUND

Frailty is a multidimensional vulnerability resulting from age-associated decline. The impact of frailty on outcomes was assessed in a cohort of vascular surgical patients.

METHODS

The study included patients aged over 65 years with length of hospital stay (LOS) greater than 2 days, who were admitted to a tertiary vascular unit over a single calendar year. Demographics, mode of admission, diagnosis, mortality, LOS and discharge destination were recorded, as well as a variety of frailty-specific characteristics. The impact of frailty on LOS, discharge destination, survival and readmission rate was assessed using multivariable regression techniques. The ability of the models to predict these outcomes was also assessed.

RESULTS

In total, 413 patients of median age 77 years were followed for a median of 18 (range 12-24) months. The in-hospital, 3- and 12-month mortality rates were 3·6, 8·5 and 13·8 per cent respectively. Receiver operating characteristic (ROC) curve analysis revealed that frailty-based regression models were excellent predictors of 12-month mortality (area under the ROC curve (AUC) = 0·81), prolonged LOS (AUC = 0·79) and discharge to a care institution (AUC = 0·84). A simple additive frailty score using six key features retained strong predictive power for 12-month mortality (AUC = 0·83), discharge to a care institution (AUC = 0·78) and prolonged LOS (AUC = 0·74). This frailty score was also strongly associated with readmission rates (P < 0·001).

CONCLUSION

Frailty in vascular surgery patients predicts a multiplicity of poorer outcomes. Optimal management should include identification of at-risk patients and treatment of modifiable risk factors.

Mid-term cost-effectiveness analysis of open and endovascular repair for ruptured abdominal aortic aneurysm

BACKGROUND

Emergency endovascular repair (EVAR) for ruptured abdominal aortic aneurysm (rAAA) may have lower operative mortality rates than open surgical repair. Concerns remain that the early survival benefit after EVAR for rAAA may be offset by late reinterventions. The aim of this study was to compare reintervention rates and cost-effectiveness of EVAR and open repair for rAAA.

METHODS

A retrospective analysis was undertaken of patients with rAAA undergoing EVAR or open repair over 6 years. A health economic model developed for the cost-effectiveness of elective EVAR was used in the emergency setting.

RESULTS

Sixty-two patients (mean age 77·9 years) underwent EVAR and 85 (mean age 75·9 years) had open repair of rAAA. Median follow-up was 42 and 39 months respectively. There was no significant difference in 30-day mortality rates after EVAR and open repair (18 and 26 per cent respectively; P = 0·243). Reintervention rates were also similar (32 and 31 per cent; P = 0·701). The mean cost per patient was €26,725 for EVAR and €30,297 for open repair, and the cost per life-year gained was €7906 and €9933 respectively (P = 0·561). Open repair had greater initial costs: longer procedural times (217 versus 178·5 min; P < 0·001) and intensive care stay (5·0 versus 1·0 days; P = 0·015). Conversely, EVAR had greater reintervention (€156,939 versus €35,335; P = 0·001) and surveillance (P < 0·001) costs.

CONCLUSION

There was no significant difference in reintervention rates after EVAR or open repair for rAAA. EVAR was as cost-effective at mid-term follow-up. The increased procedural costs of open repair are not outweighed by greater surveillance and reintervention costs after EVAR.