Well, at least one thing is for sure – we would not have been having this discussion a mere 10 years ago.
I remained sheepishly silent for most of my early career as well-intentioned invasive and noninvasive specialists criticized the state of evidence supporting the legitimacy of endovascular interventions as a competitive strategy to manage infrainguinal peripheral arterial disease. Good data from well-controlled randomized clinical trials were not available to make a case for endovascular therapies.
Dr. Michael D. Dake
Over the recent decade and a half, however, a number of contributing factors have influenced thinking and what we now consider standard of care for symptomatic disease of the superficial femoral artery (SFA). The proposal of an “endovascular first” interventional approach has evolved to a consensually agreed upon management strategy by all interested disciplines.
This did not occur on a whim. Rather, out of the shadows of relative ignorance there slowly emerged a welcomed accumulation of a large number of publications that detail the outcomes of a wide variety of randomized trials with a range of endovascular devices. This has allowed us to enter an era where valid comparisons between interventional therapies is not only possible, but allows us to more appropriately offer care to vascular patients with more nuanced strategies. These are strategies that recognize subtleties between subgroups of individuals stratified on the basis of patient demographics and lesion characteristics in a way not appreciated prior to the recent spate of endovascular device studies.
Thus, thanks to the dedication and hard work of many, we are now at a stage where we can have meaningful dialogues on a variety of endovascular topics, such as the one at hand, and proponents can argue their perspectives armed with objective evidence to support their positions. In this discussion regarding covered stent grafts and drug-eluting stents, we wish we had even more data.
Specifically, we are missing direct head-to-head comparisons between the two devices in patients with long SFA lesions. So, what do we know?
Here are some fundamental facts: The most commonly used covered stent graft for management of femoropopliteal occlusive disease is the Viabahn endoprosthesis (W. L. Gore and Associates, Flagstaff, Ariz.). The prosthesis is composed of a self-expanding nitinol stent framework and expanded polytetrafluoroethylene (ePTFE) graft with its surface lined with a coating of covalently bound heparin (Propaten bioactive surface).The only approved drug-eluting stent with significant safety and effectiveness data available is the Zilver PTX paclitaxel-eluting, self-expanding nitinol stent (Cook Medical Inc., Bloomington, Ind.).
Now in terms of the proposition, we need to discuss the meaning of the word “long” with reference to the SFA. Just what do we consider a long SFA lesion? I think all of us could agree that an arterial stenosis or occlusion of 6 cm or less is short. Lesions between 5 cm or 6 cm to 10 cm or 12 cm in length are moderately long, and disease greater than 10 cm or 12 cm is commonly characterized as long. Segments of disease greater than 20 cm long are typically considered very long or extremely long lesions from an endovascular interventional perspective.
So, how can currently available trial outcomes help us? Below, I have compiled a table that includes most of the recent clinical trial data for Viabahn and Zilver PTX in patients with long SFA occlusive disease.
OK, what can we honestly say about these data besides recognizing that we are at risk when we make any conclusions based upon cross-trial comparisons? Such an accounting of results is fraught with problems, but what we can say is that the table grossly confirms the current consensus that both devices enhance the standard of care for long lesions over traditional balloon angioplasty (PTA) and bare metal stent technologies.
Beyond this, however, it is accepted that patency results with Viabahn are lesion-length immune – that is, outcomes in long and extremely long segments of disease are not very different from the patency achieved in short lesions. This is clearly different than what is traditionally found for interventions with PTA or bare metal stents. There is not enough controlled data for extremely long lesions to reach a conclusion on drug-eluting stents; however, there is an initial suggestion that they behave in a manner more similar to stent grafts than traditional devices.
Grossly, the table suggests that the midterm and available greater than 1-year patency results with Viabahn and Zilver PTX are relatively comparable. What about the price of the device? What role does it play in our selection of the current most cost-effective endovascular strategy for long SFA lesions?