The Intracoronary Stent Revolution

By Susan Stewart, B.S.N, C.C.R.N. and Malcolm S. Pond, M.D., F.A.C.C.

Twenty two years ago in 1977, the late Swiss radiologist Dr. Andreas Gruntzig first performed balloon angioplasty as an alternative to coronary artery bypass surgery for patients with single vessel coronary artery disease. In just a few short years, amazing progress has been made in the treatment of coronary disease.

The technique of percutaneous coronary transluminal angioplasty (PTCA) developed by Dr. Gruntzig has been supplanted by coronary stenting, which has become the predominant form of nonsurgical myocardial revascularization and accounts for well over 60% of coronary revascularization procedures performed in the United States. Over 500,000 people had stents in 1998.

The technique of balloon angioplasty pioneered by Dr. Gruntzig remains hampered by two vexing problems: abrupt vessel closure during intervention, and “restenosis” or recurrent narrowing of the vessel in the ensuing 4 to 8 months. Anywhere from 30 to 50 percent of vessels treated by PTCA run the risk of restenosis.

A stent is a pliable, expandable mesh, usually made from stainless steel, which is inserted into a narrowed coronary artery to support the walls of the artery and reduce the risk of vessel closure. This device represents a landmark improvement over previous technology, and is an effective treatment for abrupt or threatened vessel closure, or for any suboptimal result following conventional balloon angioplasty (PTCA).

First used by Dr. Ulrich Sigwart in 1987, coronary stents now play a dominant role in interventional cardiology procedures worldwide. The typical candidate for a stent is a 56 year old male with coronary disease, high cholesterol levels, hypertension, and diabetes. During the stent procedure, many patients receive more than one stent, on average 1.3 per person. New self-expanding stents are being used to repair degenerated vein bypass grafts in patients who previously have had traditional coronary bypass surgery. In addition, manufacturers are designing stents for arteries as small as 2.25 millimeters in diameter, which previously could not be treated.

Since a stent is a foreign object placed inside a vessel, there has previously been significant risk associated with formation of clots in and around the stent. The problem of clot formation and “abrupt closure” has been solved in several ways. Dr. Antonio Colombo demonstrated that high pressure balloon inflation of the stent after initial deployment helped to press the stent firmly into the arterial wall and closed small gaps between the stent and the artery, thereby reducing this risk.

In addition, the chemistry of clot formation is better understood, and new drugs such as ReoPro, Integrelin, and Aggrastat are used in conjunction with platelet inhibitors Ticlid or Plavix to prevent clot formation. The venerable drug aspirin still remains a cornerstone of therapy, and patients with stents are advised to take aspirin daily for the rest of their lives.

Large clinical research trials demonstrate that stents are superior to PTCA for coronary disease. The STRESS trial (Stent REStenosis Study) and BENESTENT trial (Belgian Netherlands STENT study) reveal a 30% to 40% reduction in restenosis when comparing stents to PTCA. The reasons for this benefit in reducing restenosis include the better initial result and larger lumen achieved by stenting.

Stents will continue to be an important component of the interventional cardiologist’s arsenal of tools for revascularizing obstructed coronary arteries. They represent a revolution in technique since the early pioneering work of Dr. Gruntzig.

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