An ongoing problem with angioplasty or stenting is that about one-third of the time, the arterial blockage returns, usually within six months. It is thought that the mechanism of this phenomenon, called "restenosis", is not the progression of coronary artery disease, but rather the body's immune system response to the "injury" of the angioplasty. At this point a repeat procedure may need to be performed.

The use of stents has lowered this rate of recurrence or restenosis, and new types of devices that release clot-deterring medicine or even certain forms of radiation are being developed in the hopes of reducing this problem even further. Several investigational clinical studies determined the effective dose levels and optimum delivery systems of gamma or beta radiation (brachytherapy) and showed a significant reduction in restenosis after coronary angioplasty/stenting.The Interventional Cardiology Section at BIDMC/Harvard Medical School has helped develop these treatment modalities and offers the two FDA approved devices for brachytherapy (radiation therapy) to reduce restenosis.