Drug-eluting stents for chronic total occlusions make sense, but it is too early to close the discussionThe opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology.

Abstract

Stent implantation compared with balloon angioplasty alone has proved not only to increase procedural safety but also to reduce elastic recoil and vascular remodelling and to improve immediate and long-term clinical and angiographic outcomes in patients with coronary artery disease. The use of intravascular ultrasound-guided high pressure stent implantation has reduced the frequency of stent thrombosis. However, stents induce a neo-intimal hyperplasia during the initial 9 months after implantation, and this hyperplasia results in a binary restenosis rate of 10–40%. In addition, patient subsets with small vessels, long lesions, multivessel disease, diabetics, renal failure, or complex lesions morphology, such as bifurcations or total occlusions have an even higher incidence of in-stent restenosis. Most large pivotal studies of stent implantation included patients with coronary lesions of non-complex morphology, and the treatment results of these studies cannot necessarily be generalized to patients with more complex lesion morphology. Smaller studies have demonstrated the effect of stenting in some complex lesions such as stenosis of the proximal part of the left anterior descending coronary artery, restenotic lesions, and recanalized total coronary occlusions, whereas results have been less convincing in long lesions and lesions located in small vessels. Patients, who have stents implanted seem to fare only marginally better than those with a ‘stent-like’ result after balloon angioplasty alone. The survival rate of patients in whom the attempt to re-open a chronic total coronary occlusions fails is lower when compared with that of patients in whom the procedure is successful (10-year survival 65 and 75%, respectively). A challenge in treating total coronary occlusions percutaneously is to successfully force the guide wire through the occluded segment to the peripheral part of the vessel, and procedural success is a combination of gaining this access and obtaining a stable lumen in the vessel segment after the recanalization. Procedural success rates between 50 and 80% have been reported, but the rate seems closely linked to the selection of patients and to the morphology of the lesions. To increase success rates of chronic total occlusions treatment, special wires, and steerable dissecting and ablating devices have been introduced. However, a ‘break-through’ device is still awaited. Patients with chronic total coronary occlusion have been studied in randomized studies comparing balloon angioplasty with stent implantation. The restenosis rate was reduced from 70% in the balloon treated groups to 30% in the stent groups, with a corresponding reduction in the need for revascularisation and with no increased risk of stent thrombosis. Similar figures have been reproduced in other studies. In one study restenosis rate in the stent group was as high as 55%, which was partially explained by a very high level of lesion complexicity. A key effort in the improvement of clinical outcomes after stent implantation in chronic total occlusions is to foster a device that kills two birds with one stone, i.e. fulfils lesion scaffolding properties necessary after balloon dilatation and allows sufficient but restricted endothelialization of the stented segment. Recently, the macrolide antifungal agent, sirolimus, originally