Biodegradable Coronary Stent Safe for Long-Term Treatment

Researchers at Shiga Medical Center for Adults (Moriyama City, Japan) designed an observational prospective study that enrolled 50 patients (44 men, 6 women) from a single center in Japan between September 1998 and April 2000 to assess long-term safety of Igaki-Tamai bioabsorbable stents in coronary arteries. The patients had 63 lesions that were treated with 84 biodegradable stents, and were followed for 10 years to assess long-term major cardiac adverse events (MACE), definite and probable scaffold thrombosis, cardiac death, and noncardiac death.

The results showed that during the follow-up period, two patients were lost to follow-up, one died from unknown causes and was categorized as a cardiac death; four died from noncardiac causes; and four had mitral infarctions (MIs). In all, the survival rates free of all-cause death were 87%, free of cardiac death 98%, and free of MACE (50%), at 10 years. Cumulative rates of target lesion revascularization (TLR) were 16% at one year, 18% at five years, and 28% at 10 years; for target vessel revascularization (TVR), rates were 16% for one year, 22% at five years, and 38% at 10 years. The study was published in the April 16, 2012, issue of Circulation.

“During the process of biodegradation (one to three years), TLR and TVR reached a near plateau, suggesting that the process of PLLA biodegradation does not correlate with increased risk of clinical events,” concluded lead author Soji Nishio, MD, and colleagues of the cardiology department. “There is the possibility that if the Igaki-Tamai stent becomes drug-eluting, the TLR rates could be improved.”

“We have needed this long-term clinical data to clarify the coronary safety of the stent,” added study coauthor Kunihiko Kosuga, MD, PhD. “Our findings will pave the way for the entry of coronary stents made of biodegradable polymers into the real world of interventional cardiology.”

The Igaki-Tamai bioabsorbable stents, a product of Kyoto Medical Planning (Japan) are made of poly-L-lactic acid (PLLA), and received the European Community CE marking in 2007 to treat peripheral artery disease (PAD), but have not been approved in any country as a coronary artery stent. Fully biodegradable coronary artery stents were once hailed as a possible alternative to bare-metal stents (BMS), which carry the potential risk of stent thrombosis. The introduction of the drug-eluting stent (DES), which reduced in-stent restenosis and TLR rates compared with BMS, overshadowed biodegradable stents. More recently, reports of DES-related very late stent thrombosis (VLST) problems have emerged, making biodegradable stents once again an attractive option.

Related Links:
Shiga Medical Center for Adults
Kyoto Medical Planning