Patients with diabetes who receive drug-eluting stents are significantly more likely to experience restenosis than are nondiabetic patients, particularly if they get the Endeavor zotarolimus-eluting stent, a large Swedish registry study has found.
Cautioning that the finding should be prospectively evaluated, Dr. Ole Frobert and his colleagues wrote, “This study represents the first large-scale evaluation of the zotarolimus-eluting Endeavor stent in patients with diabetes and underlines the importance of continuous registry monitoring of new coronary stents.”
Dr. Frobert of Orebro University Hospital, Sweden, and his coauthors analyzed data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR). The registry includes information on all patients who have undergone percutaneous coronary intervention at any of 26 Swedish centers.
The study included those patients who underwent the procedure from 2004 to 2008 and who received any of four different drug-eluting stents: Endeavor, the Cypher sirolimus-eluting stent, or the paclitaxel-eluting Taxus Express or Taxus Liberte stents (J. Am. Coll. Cardiol. 2009;53:1660–7).
During the study period, 19,004 patients received 35,478 stents. The patients' mean age was 66 years. Those with diabetes (8,231) were significantly more likely to be women, and to have hypertension, hyperlipidemia, and previous coronary artery disease.
The mean follow-up duration was 29 months. Restenosis occurred in 3.5% of stents within 1 year, and in 5% within 2 years. Patients with diabetes were 23% more likely to experience restenosis than were those without diabetes, a significant difference. Compared with patients without diabetes, those with diabetes who received the Endeavor stent were 77% more likely to experience restenosis.
Among patients who received the Cypher stent, those with diabetes were 25% more likely to have restenosis than were those without diabetes.
In patients receiving the Taxus Express stent, the restenosis rate was similar irrespective of diabetes status, while diabetic patients who received the Taxus Liberte stent were slightly, but not significantly, more likely to have restenosis than were their nondiabetic peers.
Among patients with diabetes, restenosis rates were not significantly different between the Taxus stents and the Cypher stent. However, patients receiving the Endeavor stent were twice as likely to have restenosis as were patients receiving the other types.
There were similar, but smaller, differences in restenosis rates among nondiabetic patients; restenosis was 20% more likely with the Endeavor stent and 30% more likely with the Taxus stents compared with the Cypher stent.
“It was also noteworthy that in patients without diabetes, the adjusted risk of restenosis was significantly higher with the Taxus Express than with the Taxus Liberte stent,” the authors noted.
Beginning in 2005, the SCAAR database included diabetes treatment information. Neither insulin nor noninsulin treatment had any significant impact on restenosis rates among patients with diabetes. The doubled rate of restenosis among diabetic patients receiving the Endeavor stent remained regardless of treatment type.
However, the increased restenosis rates among patients with diabetes did not affect the rates of mortality or myocardial infarction, the authors said.