The heart.org has revealed that long-term data of 50 patients treated with the Igaki-Tamai stent, the first fully bioabsorbable stent implanted in the coronary arteries, shows the stent to be safe out to 10 years and associated with major adverse cardiovascular event (MACE) rates similar to those of bare-metal stents.
The fully bioabsorbable Igaki-Tamai stent is made of poly-L-lactic acid (PLLA) that is degraded to lactic acid and metabolised as carbon dioxide and water. Although the concept of the bioabsorbable stent showed promising initial and six-month results, the emergence of drug-eluting stents consigned it to the background. However concerns about very late stent thrombosis pertaining to all stents, including the drug eluters, have currently refocused attention back on biodegradable stents, including Abbott’s Absorb BVS bioabsorbable everolimus-eluting coronary stent and Biotronik’s absorbable magnesium stent.
The Igaki-Tamai stent is not available for the treatment of coronary artery disease but does have CE Mark approval in Europe for the treatment of peripheral artery disease.
In total, 63 lesions were treated with 84 Igaki-Tamai stents. After 10 years, just one patient (2%) died from cardiac-related causes, six patients (12%) died from noncardiac causes, and one patient (2%) had a lesion-related MI.
The cumulative rate of target lesion revascularization (TLR) and target vessel revascularization (TVR) was 28% and 38%, respectively.
The device, according to Dr Soji Nishio (Shiga Medical Center, Japan) and colleagues in their report, published online April 16, 2012 in Circulation, disappeared from the coronary artery within three years of implantation. The researchers believe TLR rates could be further improved by adding a drug-elution feature.
In an editorial, Dr Ron Waksman (Washington Hospital Center, DC) said there remain important unanswered questions regarding bioabsorbable stents, including how the PLLA scaffold behaves in calcified lesions, bifurcations, long lesions, or when overlapping PLLA scaffolds are needed. In addition, the optimal duration of dual antiplatelet therapy with an Igaki-Tamai type of stent is unknown. Other alternatives to the plastic PLLA polymeric scaffold include a bioabsorbable metallic alloy, with iron and magnesium the likeliest alloys of choice, given their rates of degradation.
On the whole, “the long-term results from the first-in-human experience with the Igaki-Tamai PLLA stent are encouraging,” writes Waksman. “These preliminary results demonstrate that the PLLA stent can disappear without any related adverse events.” He predicts that 10 years from now the medical community will “look back and laugh” at the days when doctors left permanent metal in the patients’ coronary arteries.
Source: theheart.org, Nishio S, Kosuga K, Igaki K, et al. Long-term clinical outcomes of first-in-man biodegradeable poly-L-lactic acid coronary stents: Igaki-Tamai stents. Circulation 2012; DOI:10.1161/CIRCULATIONAHA.110.000901. Available at: http://circ.ahajournals.org.