The new generation stents that are deigned for slow release of medication are found to be far more effective than conventional stents according to a recent study conducted on stents used for cardiac bypass . It is also found to effectively prevent the overgrowth of scar tissue, thereby reducing incidence of restenosis (re-narrowing), heart attack and death.
Stents can either be inserted into a grafted vein or into a native coronary artery during a balloon angioplasty procedure. The plague-clogged area is opened up by the balloon followed by which a stent is placed to keep the vessel patent.
Veins removed from the legs (saphenous veins) are used to replace clogged arteries in the heart (coronary arteries). However, these grafts become old over a period of time. Infact nearly 50% of all vein grafts become diseased, necessitating a second intervention in the form of either a repeat open-heart surgery or balloon angioplasty with a reinsertion of a stent within 5 to 10 years of first cardiac surgery.
Some of the causes for restenosis include build up of plaque, cholesterol debris and blood clots that hinder with the patency of the graft. The incidence of re-stenosis is much greater in the saphenous vein grafts compared with percutaneous interventional procedure involving the native coronary arteries. The new stents were found to reduce the risk of re-stenosis by as much as 4 times compared to commercially available stents.
Out of the 223 patients who underwent angioplasty for treatment of diseased saphenous vein grafts (placed 8 years ago), 139 patients had drug-eluting stents placed. The rest of them had conventional stents placed.
The incidence of heart attacks, the necessity to reopen a vein graft was considerably lower among those fitted with a drug eluting stent with the reduction rates approximating to 4 and 10 compared to 20 and 37 in those fitted with a conventional stent.
Previous studies have already established that medicated stents are effective in the prevention of scar tissue formation and narrowing in the coronary arteries, the study is the first of it's kind to explore the effectiveness in saphenous vein grafts.
The researchers intend to continue the study to find if similar results would be obtained on a long-term basis.