Efficacy Between Different Two Self-Expanding Nitinol Stents For The Atherosclerotic Femoro-Popliteal Arterial Disease

Five randomized, controlled trials failed to demonstrate any benefit of a stainless-steel stent over angioplasty alone. The nitinol stent has proven superior primary patency than balloon angioplasty in superficial femoral artery (SFA) lesions. Several studies reported stent fractures were associated with a higher risk of in-stent restenosis and reocclusion. In vitro, Stefan et al. reported the 7 different SFA stents showed differences in the incidence of high strain zones, which indicates a potential for stent fracture, as demonstrated by the mechanical fatigue tests. They claimed differences in stent design might play a major role in the appearance of stent strut fracture related to restenosis and reocclusion. Also, in retrospective study, Iida et al. reported there was significant difference in stent fracture between S.M.A.R.T. stent group and Luminexx stent group and primary patency was worse in those associated with stent fracture than in those without stent fractures. Recent stent design improvements focus on decreasing stent fracture rates which can negatively impact patency rates by rearranging strut alignment.

The design of self-expandible nitinol stents might be different depending on the developed time; The first-generation nitinol stents (e.g., LuminexxTM and SmartTM) showed a remarkably high rate of stent strut fracture. A second generation of slotted tube nitinol stents has been developed. These stents had a better flexibility, by reducing the number of connections between cells or crowns, and by configurating spiral orientation of these interconnections. Several studies reported that these nitinol stents are more fracture-resistant and more flexible, some of them providing superior patency rate (e.g., LifeTM and EverflexTM). However, the one of the important limitations to their studies is that those was the non-randomized study of relative small sample size or was confined to in-vitro. Upto date, the multicenter, randomized controlled trial for direct comparison of stent fracture and primary patency between two different nitinol stents has not been done except one study; SMART versus Luminexx stent. SMART and Luminexx stent have been classified into 1st generation self-expandable nitinol stent. Complete-SE stent of Medtronic company was different to Smart stent of Cordis company in that the configuration of interconnection of Complete-SE stent had peak-to-peak connection and more spiral orientation of interconnection, compared to mart stent. On the other hand, Smart stent has the peak-to-valley bridge and in-line interconnection. Medtronics company have claimed Complete's stent crowns have been configured to minimize crown to crown interaction, increasing the stent's flexibility without compromising radial strength. We made the hypothesis that the design of Complete-SE stent might be more fracture-resistant or effective for in-stent restenosis, compared with Smart stent.

On the other hand, to date, in previous many reports, the dual antiplatelet therapy consisted of aspirin and clopidogrel have proven to decrease the incidence of cardiovascular death, myocardial infarction, or revascularization without an increase in major bleeding in patients who underwent percutaneous coronary intervention regardless of stent type (bare metal stent or drug-eluting stent). In 2011 ESC (European society of cardiology) guideline, dual antiplatelet therapy with aspirin and a thienopyridine for at least one month is recommended after infra-inguinal bare metal stent implantation (Class I, Level C). However, there have been no the definite evidence or guideline for the optimal antiplatelet agents after stent implantation one month later. There have been many studies for the efficacy of thienopyridine in peripheral arterial disease. Also, With the potential benefit of cilostazol on vascular function in vitro, there have several previous efforts to prove the efficacy of cilostazol in patients undergoing endovascular therapy or stent implantation in peripheral arterial disease. However, still specific data regarding a variety of antiplatelet regimen are limited. Also, very few trials have effectively nor properly addressed the direct comparison for the efficacy and safety between clopidogrel and cilostazol. This trial designed to evaluate the efficacy and safety between aspirin plus clopidogrel versus aspirin plus cilostazol in patients undergoing stent implantation in femoropopliteal lesions.