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.

An update on vessel preparation in lower limb arterial intervention

Background Plain balloon angioplasty has traditionally been used to treat lower limb arterial disease but can be limited by significant residual stenosis, vessel recoil, dissection, and by late restenosis. Appropriate vessel preparation may significantly improve short and long-term outcomes. We aim to give an overview of some of the devices currently available, or under investigation, for vessel preparation in the lower limb. Main text Vessel preparation devices include those that remove plaque (atherectomy devices) and those that modify plaque. The four groups of plaque removing atherectomy devices are defined by their plaque removal method: Directional, rotational orbital and excimer laser are categories of devices investigated for plaque modification. Intravascular lithotripsy devices generate sonic pulsatile pressure waves that pass into the vessel wall cracking calcified plaques whilst sparing soft tissue. This enables dilatation of calcified lesions at low pressure by conventional balloons and enables full stent expansion. Other balloon based vessel preparation devices were designed to modify plaque and produce more controlled, lower pressure luminal expansion without major dissections and potentially with less recoil than conventional angioplasty balloons. Scoring balloons have a helical nitinol element attached to the balloon that scores plaque facilitating uniform luminal enlargement. Further specialty balloons have been developed in recent years, including the Chocolate, Phoenix and Serranator balloons. Finally, the temporary Spur self-expanding retrievable nitinol stent has a series of radially aligned spurs that are driven into the vessel wall by post-dilatation, potentially improving drug delivery. Conclusion Lesion specific vessel preparation aims to improve both short and long term outcomes through improved penetration of anti-proliferative drug, maximising luminal gain, reducing the need for stent placement and minimising intimal injury. Some forms of vessel preparation appear to improve short term outcomes; long-term outcomes remain uncertain. An overview of some of the multiple devices available for vessel preparation is presented.

Comparison of Outcomes Following Infrapopliteal Plain Balloon Angioplasty in the BASIL Trial (1999-2004) and in a Contemporary Series (2009-2013)

Objectives: To compare outcomes in patients randomized to infrapopliteal (IP) plain balloon angioplasty (PBA) for chronic limb-threatening ischemia within the Bypass versus Angioplasty in Severe Ischemia of the Leg (BASIL)-1 trial between 1999 and 2004 with outcomes in consecutive patients undergoing IP PBA at an academic vascular unit a decade later (2009-2013, Contemporary series [CS]). Methods: Individual patient data were obtained from prospective BASIL-1 (48 patients) and CS databases (73 patients). All had a minimum of 3-years of follow-up. Outcomes studied were amputation-free survival (AFS), overall survival (OS), major (above ankle) limb amputation, arterial reintervention, immediate technical success, and length of hospital stay for the index procedure and during the following 12-month period. Statistical analysis was performed using SAS version 9.4. Results: The BASIL and CS cohorts were well matched for gender, age, diabetes, previous stroke, myocardial infarction and arterial intervention, and presence of tissue loss. More patients in BASIL-1 underwent concomitant treatment of the superficial femoral (60% vs 37%, P = .01) and above knee popliteal (60% vs 34%, P = .005) arteries. Immediate technical success increased from 73% in BASIL-1 to 90% in the CS ( P = .01). Between the two cohorts, there were no differences in AFS (hazard ratio [HR] = 1.00, 95% confidence interval [CI]: 0.65-1.54, P = 1.0), OS (HR = 1.04, 95% CI: 0.66-1.62, P = .9), major amputation (HR = 0.86, 95% CI: 0.37-1.97, P = .7), or reintervention (HR = 0.61, 95% CI: 0.29-1.27, P = .2). Contemporary series patients spent significantly fewer days in hospital following the index procedure ( P = .02) and also over the following 12 months ( P = .002). Conclusions: Despite improvements in the immediate technical angiographic success of IP PBA between BASIL and the CS, there were no significant improvements in survival outcomes. Results from BASIL-2 and BEST-CLI are required in order to properly define the clinical and cost-effectiveness of endovascular treatment in such patients.