Newer-generation drug-eluting stents with biodegradable polymers provide controlled drug release with subsequent degradation of the polymer rendering the stent surface more closely to a bare-metal stent after the period of biodegradation. A newer generation, drug-releasing stent leads to fewer adverse cardiac events, such as heart-related death or heart attack linked to the same artery, than bare metal stents. Swiss researchers noted the newer drug-emitting stents may also help patients avoid the chronic inflammation associated with early-generation drug-releasing stents. Compared with a bare-metal stent, the use of a stent with a biodegradable polymer that releases the drug biolimus resulted in a lower rate of major adverse cardiac events at 1 year among patients with ST-segment elevation myocardial infarction (STEMI; a certain pattern on an electrocardiogram following a heart attack) undergoing primary percutaneous coronary intervention (PCI; procedures such as balloon angioplasty or stent placement used to open narrowed coronary arteries), according to a study in the August 22/29 issue of JAMA.s "The efficacy and safety of drug-eluting [releasing] stents compared with bare-metal stents remains controversial in patients with STEMI undergoing primary PCI. Early generation drug-eluting stents releasing sirolimus or paclitaxel from durable polymers reduce the need for repeat revascularization compared with bare-metal stents. However, vessel healing is delayed with evidence of chronic inflammation related at least in part to the persistence of durable polymer components in patients with acute STEMI.

Lorenz Räber, M.D., of Bern University Hospital and colleagues compared the efficacy and safety of stents eluting biolimus from a biodegradable polymer with bare-metal stents of otherwise identical design. The randomized controlled trial included 1,161 patients with STEMI at 11 sites in Europe and Israel between September 2009 and January 2011. Clinical follow-up was performed at 1 and 12 months. Patients were randomized to receive the biolimus-eluting stent (n = 575) or the bare-metal stent (n = 582). The primary outcome measured for the study was the rate of major adverse cardiac events, a composite of cardiac death, target vessel-related reinfarction, and ischemia-driven target-lesion revascularization at 1 year. The average age of patients was 61 years and 79% were men. The researchers found that at one year, the primary end point of major adverse cardiac events occurred in 4.3% of patients receiving biolimus-eluting stents and 8.7% of patients receiving bare-metal stents, which is a significant 4.4% absolute reduction and 51% relative reduction in the risk of major adverse cardiac events (and the prevention of 42 events per 1,000 patients treated with biolimus-eluting stents compared with bare-metal stents at 1 year). "For cardiac death alone, the percentages were smaller [(2.9% vs. 3.5%, respectively]. The treatment effect in favor of patients receiving biolimus-eluting stents was attributable to both a lower risk of target vessel-related reinfarction (0.5% vs. 2.7%) and ischemia-driven target-lesion revascularization (1.6% vs. 5.7%)." At 1 year, rates of definite stent thrombosis amounted to 0.9% among patients receiving biolimus-eluting stents and 2.1% among patients receiving bare-metal stents. The authors also observed no differences in all-cause and cardiac mortality between the groups at 1 year. "In addition to the device-oriented primary outcome measure, we recorded a lower risk of the comprehensive patient-oriented composite of death, any reinfarction, and any revascularization in favor of biolimus-eluting stents (8.4% vs. 12.2%)."