Biodegradable magnesium stents have been developed to treat blockages in coronary arteries which can degrade within four months and achieve the same results as conventional stents, conclude authors of an Article published in this week's edition of The Lancet.

But both the Article and an accompanying Comment warn longer term follow-up of the patients fitted with biodegradable stents is needed.

Coronary stents improve immediate and late results of balloon angioplasty by closing up dissections and preventing collapse of the arterial walls.

Professor Raimund Erbel, Department of Cardiology, West German Heart Centre Essen, Germany, and colleagues successfully implanted 71 of the biodegradable magnesium stents in 63 patients in their study the PROGRESS-AMS clinical trial.

The researchers found that after 12 months, the stents were safe, with no incidence of stent thrombosis (clotting within the stent), heart attack or death in any of the patients. They found that the diameter of the blood vessel within the stent (in-stent acute gain) increased by an average of 1.41mm. Whilst the stent struts disappear over time, ultrasound confirms they remain present but have been absorbed into the vessel walls, with the space left behind "filled in."

The magnesium is eventually replaced by calcium and phosphorous through the body's natural processes.

However the trial also showed that angiographic restenosis (re-blocking of the artery) occurred in 47.5% of patients who received the biodegradable stents, and 27% needed target lesion vascularisation within 12 months due to recurrent ischaemia (lack of blood flow to the tissues).

The authors say: "This study showed that absorbable magnesium stents can be delivered and expanded at high pressure in artherosclerotic coronary arteries, providing good mechanical scaffolding and achieving a lumen enlargement similar to the immediate lumen gain obtained with conventional metall
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Contact: Professor Raimund Erbel
erbel@uk-essen.de
49-201-723-4800
Lancet
31-May-2007