A fully biodegradable stent was safe over the course of a decade-long study, researchers reported.

In a single-institution study, major complication rates among 50 patients treated with Igaki-Tamai stents were similar to those seen with metal stents, according to Kunihiko Kosuga, MD, PhD, of Shiga Medical Center for Adults in Moriyama City, Japan, and colleagues.

In particular, there was only one cardiac death and just four heart attacks over the 10-year period, Kosuga and colleagues reported online in Circulation.

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

Indeed, the study supports the view that “these devices look rather safe and have acceptable follow-up data,” commented Vincent Bufalino, MD, of Midwest Heart Specialists in Naperville, Ill., who was not involved in the research.

“We don’t believe that they will replace drug-eluting stents,” he told MedPage Today in an email, “but will likely be a significant alternative in the tool box of options for coronary disease.”

But he cautioned that questions remain about how long the stents will last and what proportion of patients, when studied in a larger cohort, might need treatment for recurrent disease.

Igaki-Tamai stents, made of poly-l-lactic acid - derived from cornstarch - dissolve into the artery wall, leaving no foreign material permanently in an artery. Metal stents, on the other hand, remain in arteries, which can reclog even if the stent is drug-eluting.

Initially, investigators expected the Igaki-Tamai stents would last about 6 months on average, but in this group, whose average age was 61, they lasted about 3 years.

Nevertheless, there were only two definite scaffold thromboses, one of which was due to a metal stent implanted nearby. The other occurred early in treatment, when anti-platelet therapy was stopped owing to an acute hemorrhagic gastric ulcer.

For this analysis, the researchers examined tracked outcomes, looking mainly at major adverse cardiac events, which included cardiac death, all-cause death, nonfatal myocardial infarction, and target lesion revascularization or target vessel revascularization, as well as scaffold thrombosis.

They found:

  There were six noncardiac deaths, including two strokes, two from lung cancer, and one each from pneumonia and chronic obstructive pulmonary disease.
  There were two heart attacks that were related to the treated lesion and two that were not.
  Survival rates free of all-cause death, cardiac death, and major adverse cardiac events at 10 years were 87%, 98% and 50%, respectively.
  Cumulative rates of target lesion revascularization were 16% at 1 year, 18% at 5 years and 28% at 10 years. Rates of target vessel revascularization were similar - 16%, 22%, and 38% at 1, 5, and 10 years, respectively.

“We have needed this long-term clinical data to clarify the coronary safety of the stent,” Kosuga said. “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 stents are used in nine European Union countries and Turkey, but not in the U.S.

The researchers cautioned that the study was observational and not randomized. The 10-year period of clinical follow-up was not planned at the beginning, and late angiography and intravascular ultrasound were based on clinical indications, not the study protocol.

Finally, Kosuga and colleagues cautioned, the cohort was small, making it hard to analyze events with small numbers, such as scaffold thrombosis.

Primary source: Circulation
Source reference: Nishio S, et al “Long-term (>10 years) clinical outcomes of first-in-man biodegradable poly-l-lactic acid coronary stents: Igaki-Tamai Stents.” Circulation 2012.