The currently available evidence, as summarized above, does not allow us to reach definitive conclusions. By contrast, two opposing views can often be argued. We present a hypothetical structured debate between a bioresorbable enthusiast and a sceptic.
- Overall situation. Bioresorbable enthusiast: Revolutionary bioresorbable stents are supported by encouraging data and will expand and dominate in the future. Bioresorbable sceptic: Bioresorbable stents have no proven benefit over currently available drug eluting stents (DES) and should not be routinely used yet.
- Side branches and bifurcations. Entusiast: Bioresorbable stents are optimal for interventions involving side branches as struts will be resorbed and access to branches restored.28 Sceptic: Bioresorbable stents should not be used in bifurcations—struts may fracture during side branch dilatation and struts are thicker, i.e. more difficult to cross. More side-branch occlusions have been reported.19,29
- Long lesions. Enthusiast: The longer the lesion, the bigger the potential benefit of resorbable stent with possible elimination of late stent thrombosis and technically possible performance of bypass anastomosis at a later time. Sceptic: Overlaps with struts stacking and resulting thickness over 300 microns present a possible risk for delayed endothelialization.30
- Imaging. Enthusiast: Polymeric bioresorbable stents allow the evaluation of the coronary artery by computer tomography angiography at any time post implantation. Sceptic: The bioresorbable stent structure is not visualized and optimal expansion cannot be confirmed by angiography thus making the use of intracoronary imaging technology, such as IVUS or OCT, more frequent and thus increasing the complexity and cost of intervention.
- Myocardial infarction. Enthusiast: Patients with STEMI are ideal candidates for the use of bioresorbable stents as they are typically younger and have soft thrombotic plaques. The first encouraging data have already been presented. Sceptic: There is not enough safety data regarding the use of bioresorbable stents in the highly thrombogenic milieu of acute coronary lesions and there is no proven clinical benefit yet.
- Vasomotion. Enthusiast: Restoration of normal vasomotion is desirable and could result in a lower rate of future cardiovascular events. Sceptic: Restoration of normal vasomotion could increase the incidence of future vasospasm.
- Antiplatelet therapy. Enthusiast: If needed, antiplatelet therapy might be safely interrupted once resorption of stent struts is complete and the risk for late stent thrombosis eliminated. Sceptic: Thicker struts of bioresorbable stents might mandate a longer duration of dual antiplatelet therapy than the current generation of DES (all reported studies so far have mandated 12-month dual antiplatelet therapy).
Authors’ Personal View
Both authors have been actively involved in the Prague 19 study with the use of Absorb 1.1 stents in patients with STEMI and both support the use of bioresorbable stent technology. However, there are some remaining concerns. Scientific evidence of superiority over current-generation DES might be achieved in surrogate endpoints, such as vasomotion and vessel remodeling, but evaluation of clinical superiority would require large patient cohorts and long follow-up times (significantly longer than the resorption time of the stent). This is not likely in the near future. There is no clearly established relationship between the above-mentioned surrogate endpoints and clinical outcomes. On the other hand, evidence of noninferiority could be achievable with a medium-sized randomized study and given the immensely attractive and logical idea of bioresorbable stent, this might be enough to justify widespread use of this technology. From an even more philosophical perspective, this novel technology might lead our community to question the concept of mortality as the only valid and important endpoint. The matter of quality of life with individual patient feelings and, also, interventionalist preference might become more important and result in more diversity in our medical practice. As far as safety is concerned, it is reassuring to note that long-term (over 10 years) clinical outcomes of Igaki-Tamai poly-l-lactic acid coronary stents are excellent with no evidence of harm.31 This particular, first-inhuman bioresorbable stent is not in clinical use anymore but paves the way for future safe clinical use.