Better results with the new generation bare metal stents

The first generation bare metal stents (BMS) had a restenosis rate of 30% and even higher in high risk patients, which necessitated repeat interventions with increased morbidity and mortality (1,2). The results of the pivotal studies comparing drug-eluting stents (DES) with BMS were therefore enthusiastically welcomed when first presented in 2002. The problem of restenosis was thought to be solved. In the Scandinavian countries the use of DES was above 80% in 2006 when a study presented at the ESC meeting in Barcelona indicated that DES might increase the incidence of late stent thrombosis and potentially the mortality compared with BMS. Although results from later studies have weakened and modified this alarming message, the use of DES in most countries today is far lower than before the Barcelona meeting. The many unanswered questions regarding the safety of DES as well as better safety profile and the accumulating data of less restenosis rate with the new generations of BMS, may be the cause of this reduced enthusiasm for DES. Few studies have addressed the long-term effect of BMS on the occurrence of late restenosis, myocardial infarctions and stent thrombosis after 6 to 12 months of the coronary intervention. In this issue of the Scandinavian Cardiovascular Journal, Erik Jørgensen and co-workers from Rikshospitalet in Copenhagen demonstrate that the long-term outcome of BMS stenting is good (3). They followed 108 patients who received first and second generation BMS clinically and with coronary angiography at 6 months and 4 years after the intervention. Overall, the minimal in-stent lumen diameter was increased by 10% from 6 months to 4 years after stenting with reduction of the binary restenosis rate of 39%. Only 2 of the 108 patients had target segment angioplasty later than after one year, and no late stent thrombosis was observed. During the follow-up period 41% of the patients had a cardiac event (death, myocardial infarction or any revascularization) due to progression of the disease outside the treated segment. This study is in line with a previous trial using balloon angioplasty without stenting (4), and studies with first generation BMS (5,6) showing reduction of the restenotic process with time. In the present study the follow-up was longer than in other studies, and the same results were obtained by both first and second generation BMS. Clinically this implies that the risk of developing symptomatic restenosis or myocardial infarction later than 6 months after PCI is indeed small in patients receiving BMS, and the major long-term risk is related to development of new lesions outside the target region. The BMS used for comparison with the sirolimusand paclitaxel-eluting stents in the first pivotal randomized studies were often older generation, thick-strut stents with higher incidence of restenosis than those used in contemporary practice. Accordingly the differences in restenosis and need for revascularization between BMS and DES were higher than found in today’s practice with later generation BMS (7). Thus, in the RAVEL study with the sirolimus-eluting stent (8), and in TAXUSIV with the paclitaxel-eluting stent (9), the differences in angiographic restenosis rate between DES and BMS were as high as 26.6% and 18.7%, respectively. Since then the results with BMS have improved markedly with far less restenosis and need of repeat revascularization than reported in those earlier studies. Among the stent-related variables known to reduce the restenosis rate are changes in the geometric design, material composition of the