Clinical Implications
Self-expanding stents have been used in non-coronary interventions for many years due to their unique characteristics allowing them to adapt to varying anatomy. Previous versions using mesh designs have been limited due to uncontrolled expansion and the absence of local drug delivery, which is essential in smaller vessels. With the introduction of this easy-to-deliver, well-controlled, self-expanding stent, the interventional cardiologist has a new and unique tool in their toolbox. The above-described clinical examples are clear demonstrations of the potential of this technology. Currently, the device has indications in selected cases with extreme calibre difference along the segment to be treated, or an expected significant change in diameter in the future. Implantation success in experienced hands is quite high; however, due to its large profile, very complex calcified lesions may not always be successfully crossed whereas the latest generation of flexible, thin-strut, balloon-expandable stents could be successful in these lesions.
Some smaller clinical studies and registries have been completed as a starting point for the collection of the evidence necessary for full acceptance of this technology. The STENTYS clinical programme consists of the APPOSITION series of trials in STEMI patients, the OPEN trials for bifurcation lesions, an ADEPT trial for SVGs, and a new all-comer Sizing registry of 3,000 patients looking at cases where a STENTYS stent has been implanted where sizing has been a concern (e.g. aneurysm ectatic vessel, bifurcation/left main, CTO, SVG, tapered vessel, thrombus-containing lesion, NSTEMI, STEMI, unstable angina). The SIZING registry was initiated in June 2012 and enrolment is still ongoing; no results have yet been publicly presented or published. The randomized Comparison Between the STENTYS Self-Apposing Bare Metal and Paclitaxel-Eluting Coronary Stents for the Treatment of Saphenous Vein Grafts (ADEPT) trial in 57 patients completed enrolment in early 2014. Results on the primary endpoint of in-stent late lumen loss at six months are expected late 2014.
In terms of results, the STENTYS stent showed in the Assessment of the Safety and Performance of the STENTYS Self-expanding Coronary Stent System in Acute Myocardial Infarction (APPOSITION I) study that the culprit vessel increases by 19 % three days after a STEMI procedure, and the stent follows this increase (18 % increase).13 Patients with a STENTYS stent implanted had 0 % stent malapposition after three days, compared with 28 % malapposition for the balloon-expandable control stent in the Randomized Comparison Between the STENTYS Self-Expanding Coronary Stent and a Balloon-expandable Stent in Acute Myocardial Infarction (APPOSITION II) randomised, controlled trial.10 At one-year after STEMI in the large, 1,000-patient, Post-market Registry to Assess the Stentys Self-expanding Coronary Stent in Acute Myocardial Infarction in Real Life registry (APPOSITION III), STENTYS patients had a cardiac death rate of only 2 %. This study also demonstrated the need for low-pressure post-dilation for additional plaque modification to ensure sufficient stent expansion. The Randomized Comparison Between the STENTYS Self-apposing Sirolimus-eluting Coronary Stent and a Balloon-expandable Stent in Acute MyocardIal Infarction (APPOSITION IV) trial randomising the pre-market STENTYS Sirolimus-eluting stent to the Medtronic Resolute in STEMI patients showed a significantly greater number of fully covered stents at four months in the STENTYS arm. The feasibility of disconnecting a STENTYS stent at a bifurcation has been demonstrated in the STENTYS Coronary Bifurcation Stent System for the Percutaneous Treatment of de novo Lesions in Native Bifurcated Coronary Arteries (OPEN I) trial with a subsequent six-month MACE rate for the STENTYS DES(P) of 3.7 %.14 The Assessment of the Long-term Safety and Efficacy of the STENTYS Paclitaxel-eluting Self-expanding Stent in Coronary Bifurcation Lesions (OPEN II) bifurcation registry of 217 patients treated with the STENTYS DES(P) showed a six-month MACE of 10.1 %, and no difference in survival between patients receiving kissing balloon inflations or not at the end of the procedure.