Biodegradable stent safe for long-term treatment of coronary artery disease


The first fully biodegradable coronary artery stent implanted in humans proved safe in a 10-year study published in Circulation. The paper “Long-term (>10 years) clinical outcomes of first-in-man biodegradable poly-l-lactic acid coronary stents: Igaki-Tamai stents” was published online ahead of print on 16 April.

The biodegradable Igaki-Tamai stent (Kyoto Medical Planning) is used in nine European Union countries and Turkey – but not in the United States – to treat peripheral artery disease. However, no countries have approved the Igaki-Tamai stent for treating coronary artery disease.

“We have needed this long-term clinical data to clarify the coronary safety of the stent,” said Kunihiko Kosuga, co-author of the study and director of cardiology at Shiga Medical Center for Adults in Moriyama City, Japan. “Our findings will pave the way for the entry of coronary stents made of biodegradable polymers into the real world of interventional cardiology.”

In the study, researchers tracked 50 Japanese patients (44 men, average age 61 years old) who received 84 Igaki-Tamai stents to treat 63 lesions between September 1998 and April 2000. The stents were not coated with drugs. Overall clinical follow-up (>10 years) of major adverse cardiac events and rates of scaffold thrombosis were analysed together with the results of angiography and intravascular ultrasound. Major adverse cardiac events included all-cause death, nonfatal myocardial infarction and target lesion revascularisation/target vessel revascularisation.

During the overall clinical follow-up period (121±17 months), two patients were lost to follow-up. There was one cardiac death, six non-cardiac deaths and four myocardial infarctions. Survival rates free of all-cause death, cardiac death and major adverse cardiac events at 10 years were 87%, 98% and 50%, respectively. The cumulative rates of target lesion revascularisation  (target vessel revascularisation) were 16% (16%) at one year, 18% (22%) at five years and 28% (38%) at 10 years. Two definite scaffold thromboses (one subacute, one very late) were recorded. The latter case was related to a sirolimus-eluting stent, which was implanted for a lesion proximal to an Igaki-Tamai stent. From the analysis of intravascular ultrasound data, the stent struts mostly disappeared within three years. The external elastic membrane area and the stent area did not change.

“Fully biodegradable stents may hold an important position as the next generation of coronary devices,” Kosuga said.


About the Igaki-Tamai stent

The Igaki-Tamai stent is formed of biodegradable polymer PLLA (poly-L-lactic acid). The stent has the characteristics of being dissolved into water and carbon dioxide and absorbed into vessel tissue within a few years after implantation. According to Kyoto Medical Planning, the stent is also indicated for patients who could not receive a stent due to with metal allergies. Even though a stented segment becomes narrow again, the implanted PLLA stent, which does not remain in the body permanently, will not interfere with other procedures such as restenting, Furthermore, PLLA stent is more useful for containing drugs compared to metal stents, and thus, it has been intended as a platform for drug eluting stents, the company states on its website.