Real-world data from Europe indicate that drug-eluting stents have higher rates of stent thrombosis at nine months post-implantation than indicated in clinical trials, according to an article in the May 4th issue of the Journal of the American Medical Association.

Physicians are now using drug-eluting stents for a wide variety of clinical and anatomic situations, many of which have not been evaluated in randomized studies, according to background information in the article. Data outside of clinical trials is limited regarding the risks of thrombosis beyond 30 days.

Ioannis Iakovou, MD, and colleagues analyzed the incidence, predictors, and clinical outcome of stent thrombosis at 9 months of follow-up in an observational study conducted at 3 hospitals in Germany and Italy.

A total of 2,229 patients underwent successful implantation of sirolimus-eluting (1,062 patients, 2,272 stents) or paclitaxel-eluting (1,167 patients, 2,223 stents) stents between April 2002 and January 2004.

At the 9-month follow-up, 29 patients (1.3 percent) had stent thrombosis (9 [0.8 percent] with sirolimus and 20 [1.7 percent] with paclitaxel), substantially higher than rates reported in major clinical trials (0.4 percent at 1-year for sirolimus and 0.6 percent at 9-months for paclitaxel).

Among the 29 patients, 13 died (case fatality rate, 45 percent) and the majority of others experienced nonfatal myocardial infarction. Independent predictors of stent thrombosis included premature antiplatelet therapy discontinuation (thrombosis occurred in 29 percent of these patients), kidney failure, and diabetes (27 percent of the patients had diabetes).