Placement of a stent following angioplasty has become standard practice because it decreases the rate of coronary vessel restenosis. However, even with a stent present, restenosis can occur in as many as one third of patients. Patients with diabetes, longer coronary artery lesions, or smaller vessels are at especially increased risk of restenosis. Coating stents with sirolimus, a potent inhibitor of cell proliferation, has been shown to reduce restenosis rates in small studies of simple coronary lesions. Moses and colleagues reported on the use of sirolimus-coated coronary stents in more complex coronary lesions at higher risk for restenosis.
The authors enrolled patients with a newly diagnosed single lesion in a native coronary artery. Patients were excluded for myocardial infarction (MI) occurring within the previous 48 hours, or if angiography revealed an ejection fraction below 25 percent, thrombus or severe calcification in the target vessel, or need for treatment of additional coronary lesions. The number of excluded patients based on these criteria was not given.
A total of 1,058 patients were randomized to standard stent placement or the use of a sirolimus-coated stent. As designed, more complex coronary lesions were included. Forty-two percent of the trial participants had multivessel disease, 31 percent had a history of MI, and 26 percent had diabetes. Treatment was attempted in smaller vessels (average diameter: 2.8 mm) and longer lesions (mean length: 14.4 mm). All patients received aspirin in a dosage of 325 mg daily and clopidogrel in a dosage of 75 mg daily, which was continued for three months following the procedure. Glycoprotein IIb/IIIa inhibitors were used in 60 percent of patients, at the discretion of the treating physician. The sirolimus coating was designed to release 80 percent of the active drug within the first 30 days of placement.
Patients were followed over nine months for death from cardiac causes, MI, or the need for repeat revascularization. No significant differences were found between the stent types in the rates of death (0.6 percent to 0.9 percent) or MI (2.8 percent to 3.2 percent), but the need for repeat revascularization decreased in patients with sirolimus-coated stents (4.1 percent) compared with standard uncoated stents (16.6 percent). In the subgroup of patients with diabetes, restenosis occurred more often, but the need for revascularization was reduced similarly by sirolimus, from 22.3 percent to 6.9 percent. Other subgroups of patients (i.e., men, women, and patients with smaller vessels, longer lesions, left-anterior descending artery lesions) had reduced restenosis rates by the same magnitude with the use of sirolimus.
The authors conclude that the use of sirolimus as an antiproliferative coating on coronary stents can reduce restenosis rates in patients with more complex coronary lesions.
editor’s note: Restenosis after angioplasty was an unfortunately common occurrence before placement of stents became standard practice. Further reductions in restenosis rates with radioactive or drug-coated stents have been demonstrated repeatedly. These coated stents will no doubt become more widely employed in the near future. Stent coatings have a limited duration of action, however, and longer follow-up will be needed to see if these early reductions in restenosis rates translate into improved long-term coronary vessel patency as well.—B.Z.