Servier – Phlebolymphology

1.4.1 Controversy: Do we really need a stent in long SFA lesions?

No: Drug eluting balloons (DEB) are the answer.
T. Zeller

The author started by presenting recent data regarding subintimal angioplasty of transatlantic inter-society consensus II class C/D lesions (TASC II C/D lesions), stressing a primary 12-month patency of 52% to 73% (Sidhu R et al. Vasc Endovascular Surg. 2010;44:633-637; Kim SJ et al. Circ J. 2010;74:1959-1964). Then, he introduced several studies and a meta-analysis concerning the results of the drug-eluting balloon (DEB) in the superficial femoral artery (SFA), showing a clear benefit of DEB compared with standard angioplasty (Cassese S et al. Circ Cardiovasc Interv. 2012;5:582-589). Subsequently, he compared the results of DEBs with the drug-eluting stents (DES). To do so, he proposed the Propensity Score Analysis to allow an “apples-to-apples” comparison under nonrandomized conditions and to permit the balance of covariates to make more valid inferences about treatment effects.

He concluded that: (i) DEBs potentially overcome the Achilles’s heel of reduced durability of endovascular revascularization; (ii) with the limitations of a retrospective single center study, the Propensity Score statistical method adds rigor and reliability to head-to-head comparisons of real-world cohorts with approximately 90% of bias removed from confounding variables; (iii) IN.PACT Admiral (DEB) and Zilver PTX (DES) offer similar safety and efficacy outcomes to patients treated for claudication and rest pain due to long (roughly 19 cm) SFA lesions; and (iv) DEBs offer a broader anatomical applicability and bring all the advantages of a “leave nothing behind” first-line therapy.

Yes: Newest stents are perfect for the job.
Y. Gouëffic

The author started by affirming that, currently, endovascular treatment of femoropopliteal lesions superior to 15 cm as a first-choice treatment remains controversial. Different types of endovascular devices could be used to treat long femoropopliteal lesions such as simple balloons, bare metal or covered stents, and drug-eluting devices. Presently, nitinol self-expanding stents appear to be the gold standard of the endovascular treatment for femoropopliteal lesions inferior to 15 cm. Indeed, nitinol alloys allow scaffolding of the arterial wall in order to prevent elastic recoil, negative remodeling, and keep a greater flexibility in a tortuous physical environment. Most of these devices have been assessed in short, femoropopliteal lesions; therefore, the results cannot be generalized to longer femoropopliteal lesions.

Indeed, the treatment of long femoropopliteal lesions is still challenging for different reasons, which are especially related to the clinical status of the patients, technical factors, mechanical stress submitted to the femoropopliteal axis, and mechanical properties of the devices. Newer generations of longer nitinol self-expanding stents could allow endovascular treatment of longer femoropopliteal lesions thanks to their scaffolding properties and their resistance to compression and fracture in this tortuous physical environment. The author concluded that: stenting of trans-atlantic inter-society consensus II class C/D lesions (TASC C/D) femoropopliteal lesions appears to be a safe, efficient, and durable repair; early narrow clinical and duplex scan follow-up of long stents is mandatory to detect potential thrombosis and in-stent restenoses events; primary stenting of TASC C/D needs ongoing surveillance and longer follow-up, given the high rate of critical limb ischemia; perhaps drug-eluting stents for TASC C/D femoropopliteal lesions may be the future, pointing to STELLA-PTX trial (STEnting Long de L’Artère fémorale superficielle- Zilver PTX) results, which are going to be presented soon.

1.4.2 Controversy: When a stent is needed, do you choose a bare stent or a covered stent?

Bare stent and I’ll tell you why.
T. Zeller

The author began his presentation by stating that the superficial femoral artery (SFA) territory has much higher rates of restenosis compared with other vascular territories (coronary, carotid, iliac, renal, etc). As such, covered stent implantation in femoropopliteal artery disease is an appealing concept to prevent neointima growth into the stent lumen, which is the background of in-stent restenosis development. However, no study, so far, has shown a significant benefit for the implantation of Viabahn endoprosthesis over bare metal nitinol stent placement in lesions shorter than 20 cm. The recently published VIASTAR trial (Viabahn Endoprosthesis With PROPATEN Bioactive Surface [VIA] Versus Bare Nitinol Stent in the Treatment of Long Lesions in Superficial Femoral Artery Occlusive Disease) has shown superior patency outcomes only for femoropopliteal lesions longer than 20 cm (Lammer J et al. J Am Coll Cardiol. 2013;62:1320-1327). Endograft implantation has certain limitations such as unknown duration of dual antiplatelet therapy (4 weeks for bare metal nitinol stents), occlusion of potential collateral vessels, and the higher device costs. Edge stenosis remains the Achilles’s heel of endograft implantation in peripheral arterial disease. Thus, provisional bare metal nitinol stent placement remains the therapy of choice in trans-atlantic inter-society consensus II class A/B (TASC II A/B) femoropopliteal lesions. Second and third generation bare metal stent trials have resulted in satisfying 1-year primary patency rates of approximately 80% in these lesion subcohorts (Laird JR et al; RESILIENT Investigators. Circ Cardiovasc Interv. 2010;3:267-276; Scheinert D et al. J Endovasc Ther. 2011;18:745-752). The author concluded that: (i) bare metal stents offer superior technical results over balloon angioplasty due to their better acute and mid-term performance; (ii) dedicated stent designs such as interwoven closed-cell design and 3-dimensional helical design might improve technical and clinical results of bare metal stents (1-year patency ≥80%); (iii) bare metal stents show almost no additional loss of patency after 1 year; and (iv) Viabahn endografts might improve outcomes in TASC C/D lesions, however with higher costs, coverage of collateral vessels, and an unknown duration of dual antiplatelet therapy.

Covered stent without any doubt.
M. Bosiers

The most common mode of failure after a technically successful stenting in the superficial femoral artery (SFA) is restenosis due to neointimal hyperplasia. Bare metal stents (BMS) are implanted in order to provide scaffolding for the plaque that is pushed aside during percutaneous transluminal angioplasty (PTA), and the chronic outward force ensures that vessel recoil is minimized. However, cells can continue to proliferate through the stent struts, eventually resulting in restenosis; the likelihood of this occurring is theoretically proportional to the length and severity of the lesion. A covered stent (CS), by contrast, provides a barrier to hyperplastic tissue ingrowth. The failure mechanism of a CS is similar to a bypass graft—edge stenosis, possibly followed by CS thrombosis, is generally the culprit. These mechanisms are theoretically much less dependent on lesion length.

Both BMS and CS for femoropopliteal occlusive disease treatment have been studied in the literature; however, lesion length and severity, term of study, and patency definitions in various studies have been different, making it hard to compare results. Luckily, we now have level-one evidence showing a difference between BMS and CS. The recently published VIASTAR study (Viabahn Endoprosthesis With PROPATEN Bioactive Surface [VIA] Versus Bare Nitinol Stent in the Treatment of Long Lesions in Superficial Femoral Artery Occlusive Disease; Lammer J et al. J Am Coll Cardiol. 2013;62:1320- 1327) randomized the latest generation, heparin-bonded CS to BMS in patients with complex femoropopliteal lesions (average lesion length was 18 cm). This multicenter study showed a primary patency difference between the arms at year 1 in favor of CS (78.1% vs 53.5%, P=0.009). The VIPER study (Gore Viabahn endoprosthesis with Heparin Bioactive Surface in the Treatment of Superficial Femoral Artery Obstructive Disease; Saxon RR et al. J Vasc Interv Radiol. 2013;24:165-173) was a single-armed, 119 limb study utilizing the newest version of CS. The patient demographics and lesion characteristics are similar to the previous study mentioned. In this study, the heparinbonded CS showed a one-year primary patency rate of 73%. Additionally, there was no difference in the patency between patients with lesions <20 cm and those with lesions >20 cm, indicating that even very long lesions could be treated successfully. The results did show that CS oversized by <20% at the proximal edge (instructions for use recommends 5% to 20% oversizing) significantly improved the results (88% primary patency). The single-armed 25-cm VIABAHN Study enrolled lesions that are even more difficult than the lesions studied in VIASTAR and VIPER. This study, which only enrolled patients with lesion lengths greater than 20 cm, had 93% chronic total occlusions and a mean lesion length of 26.5 cm; all were treated with heparin-bonded CS. The interim 12-month primary patency was 66.7%, which is encouraging considering the extremely advanced disease of the patients studied.

Consequently, the author concluded that data for the newest generation of heparinbonded CS clearly show superior patency results to BMS when studied in difficult lesions. When a stent is required in femoropopliteal interventions, a covered stent should be chosen.

1.4.3 Visceral arteries

Renal artery stenting: are there any indications left?
L. Mendes Pedro

Renal artery stenosis is a cause of arterial hypertension in around 1% to 4% of all hypertensive populations. There are three therapeutic options: medical treatment, conventional surgery, and endovascular stenting.

The indications for open surgery are: (i) concomitant need for aortic or visceral surgical reconstruction; (ii) distal or branch renal stenosis; (iii) very calcified lesions; (iv) endovascular surgery is not possible; and (v) complications of endovascular treatments and renal revascularization in children. The technical success in renal stenting cases are excellent (95% to 100%) with mortality <1%, restenosis between 10% and 20%, primary patency between 75% and 82% in 5 years. Accordingly, the author stated that most patients with renal stenosis may not require intervention, and therefore, should be managed medically.

In conclusion, renal “prophylactic” interventions, driven by image, are ineffective. The randomized control trial did not address severely symptomatic patients where the benefit of revascularization is usually accepted, more prospective studies with improved patient and lesion selection criteria are needed.

References:
Nolan et al. J Vasc Surg. 2005;41:46-52; Sivamurthy et al. J Vasc Surg. 2004;39:565- 574.

Renal denervation: how does it work, who should be treated?
I. Baumgartner

According to the author, drugs work, but not as well as you might think. Thirty-five percent of patients treated remain uncontrolled. The contributing factors to uncontrolled hypertension include physician inertia, patient compliance, and resistant hypertension. Strong demands exist for a new and safe therapy to control resistant hypertension.

The initial proof-of-control concept study, Simplicity HTN-1, and the multi-center, prospective, randomized Simplicity HTN-2 trial investigated the effect of radiofrequencybased and catheter-based renal denervation (RND) in patients with resistant hypertension.

The catheter is introduced through the femoral artery and is threaded through the renal artery near each kidney. Once in place, the tip of the catheter delivers low-power radiofrequency energy to several locations to disable the sympathetic nerves throughout the artery. The author treated 153 patients with a 36-month follow-up. Eighty percent of patients treated had superior reduction in systolic baseline pressure up to 10 mm Hg.

In conclusion, the author suggests that transcatheter renal sympathetic denervation is safe and simple to be performed. Significant reductions in blood pressure were achieved in patients with multidrug resistant hypertension. The effect has been sustained through at least 36 months. There was no significant decline in renal function.

Acute visceral ischemia: how to improve survival?
Y. Castier

In a systematic review of 45 observational studies, including 3692 patients with acute mesenteric ischemia, in-hospital death rate was 70%. The first step to improve the outcome is to make the diagnosis. Only 50% of acute mesenteric ischemia is identified before surgical exploration or death. Early diagnosis makes the difference and is the major prognostic factor.

The surgeon must be aware of abdominal pain by doing a reassuring examination and also be aware of atherothromboembolism risk factors. Other nonspecific signs include nausea, vomiting, diarrhea, tachycardia, and abdominal distention.

The CT scan is the gold standard with 96% sensitivity and 94% specificity. The signs in CT include intestinal wall thickening, delayed mucosal enhancement, bowel dilatation, mesenteric vessel occlusion, ascites, and solid organ infarcts.

There are no early and specific biomarkers as hyperlactatemia is not an early biomarker. It is a multimodal and multidisciplinary management composed of gastroenterology, anesthesiology, radiology, digestive surgery, and vascular surgery.

In conclusion, early diagnosis and revascularization promotes the best survival rates.

1.4.4 Leg arteries

What is the angiosome concept? Is it more useful than pedal arch patency?
P. Schneider

Taylor and Palmer first introduced the angiosome concept in 1987. They analyzed the blood supply to the skin and subcutaneous tissues through ink injection studies, dissection, perforator mapping, and radiographic analysis of fresh cadavers. A 3-dimensional network of vessels was identified as the blood supply source for specific blocks of tissue, further interconnected by a rescue system called “choke-vessels.”

The anatomical planning of vascular reconstruction based on angiosomes involves understanding the connections among foot and ankle branches and associated angiosomes.

The angiosome strategy is less important in a fully intact pedal arch, more likely in nondiabetics, in Rutherford category 4 with no tissue loss, lesions above the ankle, and superficial ulceration (<10 mm in diameter and toe pressure ≥50 mm Hg after percutaneous transluminal angioplasty (PTA). The angiosome concept helps to guide therapy for Rutherford category 5 lesions (which tibial artery to revascularize?) and Rurtherford category 6 lesions (how many tibial arteries to revascularize?).

The angiosome concept is an opportunity for targeted therapy. Healing is more likely and is faster after direct revascularization of the correct angiosome. The angiosome concept helps explain some of the variability in revascularization results for critical limb ischemia, especially in diabetics with compartmentalized pedal circulation.