VDM Speaks with Walter Dorigo, MD, about Limb Salvage in Diabetics with CLI Using the Gore Propaten Heparin-Bonded ePTFE Vascular Graft

What do the study data show thus far regarding treatment of infrainguinal critical limb ischemia using the heparin-bonded ePTFE vascular graft?

In this study, we analyzed the results of the Gore^® Propaten^® bioactive heparin-bonded ePTFE vascular graft (W.L. Gore & Associates, Inc., Flagstaff, Arizona) in below-knee revascularization in diabetic patients with critical limb ischemia (CLI) and we compared them with the results obtained with autologous saphenous vein (ASV). Data were extracted from the Propaten Italian Registry Group Database, which involves seven Italian vascular centers and includes all the interventions performed since January 2002. The results of our registry received quality validation and certification by an external company in 2009 and they were the object of several papers, including the one published in the Journal of Vascular Surgery in May 2010. Up to September 2010, the database includes data on more than 500 below-knee revascularization procedures. Data concerning ASV bypasses were collected from the institutional databases of the same centers for the same time period. Our study group included 180 diabetic patients who received the Gore Propaten vascular graft and 133 patients who received ASV. Despite the presence of significant differences between the two groups in terms of anatomical parameters (higher percentage of patients with a run-off score characteristics (higher percentage of reinterventions and need for adjunctive distal procedures in heparin-bonded ePTFE vascular graft patients), the perioperative results were similar between the two groups. As expected, the follow-up results were in favor of ASV in terms of primary patency, but secondary patency and limb salvage were again similar between the ASV and heparin-bonded ePTFE vascular graft groups. Among factors affecting outcomes in heparin-bonded ePTFE vascular graft patients, reintervention was found to significantly affect both primary and secondary patency, while the presence of ulcers rather than rest pain and a poor run-off score were found to significantly affect secondary patency. These data confirm the superiority of ASV in terms of primary patency in diabetics with CLI; however, they also demonstrate the excellent performance of the Gore Propaten vascular graft in the long term, particularly in terms of limb salvage, which probably represents the main outcome in these critical patients. The Gore Propaten vascular graft may represent a safe alternative to ASV when it is unsuitable and, in our opinion, its use can also be recommended in selected subgroups, even in the presence of good-quality vein (patients with rest pain, with good run-off status, in primary interventions rather than in reinterventions).

Tell us about the study’s design and scope. What were the inclusion and exclusion criteria and primary and secondary endpoints?

As I said before, this study was designed as the revision of a multicenter registry, retrospectively compiled from 2002 to 2007 and prospectively from 2008 to 2010, including all the interventions performed with the Gore Propaten vascular graft at the participating centers. Data concerning the interventions performed with ASV in the same period of time were retrospectively collected. Being a registry, no inclusion and exclusion criteria were requested; in any case, the choice to use the Propaten graft was at the surgeon’s discretion and not only in the absence of a suitable vein. Early results were analyzed in terms of graft patency, major amputation rates and mortality. Follow-up results were analyzed in terms of primary and secondary graft patency, limb salvage and survival.

What type of imaging technology was used to determine procedural outcomes?

Intra-operative results were assessed by angiography. At discharge, patients underwent ankle-brachial index (ABI) measurement, whereas follow-up consisted of clinical examination, ABI measurements and graft duplex examination. Graft failure was diagnosed when ABI deterioration was associated with duplex evidence of graft thrombosis. Angiography and reintervention were indicated when recurrence of CLI or acute limb ischemia occurred.

How long will the patients be followed in this study and what is the follow-up protocol?

Our patients will undergo lifelong surveillance with a protocol including controls within the third post-operative month, at 12 months and each year thereafter. It is a considerable workload, but we strongly believe that the only way to truly understand how this graft works is to have firm long-term outcome data. At the moment, more than 95% of our patients have been followed for a mean period of 26 months, which allows an estimation of results at 48 months with good statistical power.

Describe the features of the Propaten vascular graft.

Propaten is a new-generation heparin-bonded ePTFE graft; in fact, heparin does not simply cover the graft surface, but is immobilized on the graft, producing a surface microstructure with stable, covalently bound heparin. The covalent endpoint linkages maintain their bioactivity on the antithrombin sites of the bound heparin up to 12 weeks post-implantation, offering uniform surface heparinization, sustained in-vivo heparin bioactivity and increased antithrombotic and anti-inflammatory properties as demonstrated by experimental studies.

Where do you see things headed in the treatment of critical limb ischemia?

It seems clear that the introduction and widespread application of endovascular techniques have changed the paradigm of treatment of CLI. Particularly in diabetics with diffuse tibial vessel disease, endovascular surgery nowadays allows the treatment of patients who once would probably have been excluded from any possibility of revascularization. For this reason, an endovascular approach can be suggested as the first-line therapy in these patients. However, several studies and the recently published BASIL trial demonstrated that the Achille’s heel of endovascular surgery is the long-term durability, suggesting a persistent role for open surgery in this setting. Open surgery still represents an excellent option, not only in the case of endovascular failure, but also as a first-line strategy in clinically and anatomically complex cases (concomitant involvement of the superficial femoral artery and the popliteal-tibial region). In this setting, the Gore Propaten vascular graft is, in our opinion, an excellent alternative to ASV, not only when it is unsuitable or of poor quality, but also as a primary choice in selected patient subgroups.

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Dr. Walter Dorigo was born in Florence on August 30, 1970. He graduated from the School of Medicine of the University of Florence in 1995. He entered the post-graduation program in Vascular Surgery at the University of Florence and obtained the title of Specialist in Vascular Surgery in 2001. Since 2002, Dr. Dorigo has been a research fellow in Vascular Surgery at the University of Florence, where he also holds academic and teaching positions. Dr. Dorigo is a member of the executive committee of the Italian Society for Vascular Investigations (SIDV-GIUV) and the Italian Society of Young Surgeons (SPIGC). He is also a member of the Society for Vascular Surgery (SVS), the European Society for Vascular Surgery (ESVS) and the Italian Society for Vascular and Endovascular Surgery (SICVE). Dr. Dorigo has authored or co-authored more than 40 papers published in indexed international journals and several chapters in international and national books. He personally presented the results of his studies at several national and international meetings.