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 R�ber, 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%)."