Future devices: bioabsorbable stents

There are many advantages to bioabsorbable stents, including the potential to inhibit intimal hyperplasia by avoiding prolonged foreign body reaction and/or releasing antiproliferative drugs during degradation. The bioabsorbable polymer poly-l-lactic acid (PLLA) is used as a biodegradable coating of permanent metallic stents but can also be used to manufacture complete stents, at the expense of a greater recoil. Clinical, angiographic and intravascular ultrasound results at four years with the first stent tested (Igaki Tamai, Igaki, Japan) show patency rates similar to the rates expected with stainless steel stents and full reabsorption. Magnesium stents are another, perhaps more encouraging, development because they retain mechanical properties similar to conventional metallic stents. Full degradation of the magnesium alloy used to manufacture the Biotronik Lekton Magic stent requires 6–8 weeks. In man, initial clinical experience with this stent has been gained in patients with critical lower limb ischaemia. An ongoing study is testing its safety and efficacy in human coronary arteries.