US:THE BEST helpers are the ones that leave when their work is done. That's the approach pharmaceutical giant Abbott is testing with a new type of stent - the medical device inserted into arteries to improve bloodflow.

Their absorbable stent, designed to "disappear" over time, has shown promise in two-year follow-up trials, as reported in the Lancet.

Stents have revolutionised treatment of narrowed arteries, which increase the risk of heart attack. By inserting a catheter into an artery in the leg or arm and guiding it to the narrowed stretch, doctors can widen the blood vessel and leave a supporting stent in place.

Stenting is far less invasive for the patient than a heart bypass, which involves a general anaesthetic and opening the chest, and an estimated 8,000 stenting procedures are to be carried out in Ireland this year.

Leaving such foreign bodies in arteries can elicit a negative reaction, and recent advances have seen coated stents that elute their own drugs on site to help overcome potentially damaging responses, such as inflammation and re-narrowing of the artery.

Abbott Vascular in Illinois is taking a step further with its absorbable stent, made from poly-L lactic acid and coated with poly-D,L-lactide.

The multi-centre Absorb study followed 29 of 30 patients with the biodegradable stents over two years and found the device was bioabsorbed and "clinically safe". One patient had a major adverse event.

The results have promise, but a Lancet commentary calls for larger trials before considering this a breakthrough.