Implantation of bioresorbable stents (BVS)
Non-metal resorbable intracoronary prosthesis
Since the end of the last decade, the market has welcomes a new type of intracoronary prosthesis that is also resorbable over time, and eventually disappears. After implantation, this plastic polylactic acid material that is expanded with a balloon, just like metal stents, acts as a scaffold for the atheromatous coronary wall, and revascularises the affected vessel. Like metal drug-eluting stents, the BVS, through a polymer, slowly releases an antiproliferative drug (Everolimus) that prevents heavy scarring with re-stenosis. For 6 months, it supports the wall until it is healed, preventing recoil and developing a neointimal coating. At the end of this period, it no longer performs this support function and a hydrolysis process begins that gradually degrades the device until it disappears. When this occurs, the coronary artery recovers its functional capacity to dilate or contract, as needed, something that is impossible in arteries treated with metal stents.
Using a metaphor, it is like a fracture that never leaves the cast that cures it. Although these devices are evolving and only initial models are available, they are the subject of considerable research. Our experience began in early 2011, and we have obtained information from more than 900 patients who have benefited from this advance. This enabled the publication of significant scientific contributions about the technique and its use in complex lesions such as those found in bifurcations, long lesions or lesions with prior arterial occlusion. In general, they are indicated in young people, with soft atheromatous plaques and in different clinical conditions, including acute myocardial infraction. Their use in calcified lesions is more questionable, unless they are previously dilated. Neither do they seem suitable for small vessels, as they are somewhat thicker than metal stents. Compared with metal drug-eluting stents, the BVS is slightly thicker, creating a larger theoretically thrombogenic area, and prone to sub-acute or tardive thrombosis. Anti-thrombotic treatment is therefore more prolonged in treated patients.
In any event, studies to date show similar short and long-term results to those obtained with metal drug-eluting stents (DES), with the same percentages of initial and tardive success and the same initial and tardive complications, both in very low percentages. The experience has considerably improved the approach and techniques required for their increasingly effective and safe use, which is expected to increase in the near future. The system’s greatest advantage is that it disappears when it is no longer necessary.