Sirolimus-eluting stents compare favorably to bare metal stents in a number of ways. However, sirolimus-eluting stents show a higher rate of very late thrombosis, leading to an overall similar rate of thrombosis with both stent types, according to Dutch researchers.
In the April 15th issue of the
American Journal of Cardiology, Dr. Joost Daemen and colleagues at Erasmus Medical Center, Rotterdam note that there is a lack of information on the performance of these stents in "real world" patients not involved in clinical trials.
To gain further information on stent performance in everyday practice, the researchers enrolled 508 consecutive patients treated with sirolimus stents over a period of six months in 2002. They were compared with 450 patients treated with bare metal stents during the preceding six months.
After four years of follow-up the incidence of composite major adverse events, comprising all-cause death, myocardial infarction and target vessel revascularization, was significantly lower in the sirolimus than in the bare metal group (23 per cent versus 28.7 per cent).
This was also true of target vessel revascularization alone (12.2 per cent versus 17.8 per cent). However, there were no differences in rates of all-cause mortality or cardiac death.
Moreover, although there was no difference in the overall rate of stent thrombosis (2.3 per cent versus 2.2 per cent), there was significantly less early thrombosis in the sirolimus group (0.4 per cent versus 1.8 per cent). While there was no very late stenosis in the bare metal group, very late thrombosis occurred in 1.4 per cent of the sirolimus patients.
Mortality rates in both groups were higher than those encountered in randomized trials, which, the investigators suggest, is a reflection of a higher risk among patients in clinical practice, "as opposed to carefully selected randomized trial patients."
"In conclusion," Dr. Daemen told Reuters Health, "after four years, sirolimus-eluting stents were found to remain safe and effective compared with bare-metal stents. Nevertheless, the higher rate of very late stent thrombosis remains a concern. Longer term follow-up will be required to determine the extent of this problem."
Am J Cardiol 2008;101:1105-1111
