Angioplasty was initially in the 1970s using a long balloon to dilate the narrowed portion of the affected artery.
The balloon was guided to the required location within the blood vessel through a narrow tube known as the catheter.
However, the drawback with Plain Balloon Angioplasty was that it had a 35–40% probability of redevelopment of a block in the same area (Restenosis).
Later by the early nineties, Bare Metal Stents (BMS) came into the arena which are metal tube-like devices that can be compressed over a balloon and later expanded in the narrowed portion of the artery.
These stents were initially composed of stainless steel and later improvements were made with the introduction of alloys such as cobalt-chromium.
Though these stents proved to be a defining moment in treating CAD, as they brought down the restenosis rate from 40% to 25%, a 25% rate remained a problem.
This led to the development of a newer generation of stents that had better designs and thinner struts.
The thinner struts gave the stents enhanced flexibility and deliverability at the desired regions.
Still, the percentage of Restenosis remained at 25%.
Robust research and advancements led to the introduction of the next evolution in stent technology, the Drug-Eluting Stent. The first-generation Drug-Eluting Stents (DES) were composed of the same core materials as BMS with a drug-coated onto the stents.
These drugs had an anti-proliferative activity which selectively stops the scar tissue proliferation at the targeted area of treatment.
This innovation substantially reduced the restenosis rate to a mere 3–5%. Also, the novel 3rd generation DES stents are excellent devices lending enhanced flexibility with decreased restenosis. With a 3–5% rate of restenosis with DES, the majority of patients with even multiple blocks can be treated with angioplasty and can provide a 95–97% probability of disease-free survival.
The most recently developed stents (called the 4th generation) or the biodegradable stents are composed of substances such as heavy polymers that get dissolved within the body tissues over 3–4 years after the interventional procedure.
Their advantage is that they get disappeared, after performing their job.
Though this is a new strategy and has yielded positive results, their long term results are still pending.
Overall, though there is so far no evidence to doubt this technology and its benefits, the only cause of concern is the absence of long term data.
