Stents are metallic hollow devices that serve to scaffold an area of obstruction within the coronary artery. The stents made today are 2.0 to 4.5mm in diameter and vary in length from 5mm to 40 mm. Most stents are made of stainless steel. The first stent was successfully implanted in a human in 1993 in Europe. Shortly thereafter in 1994, the first stent was successfully implanted in the U.S. Then followed two large, randomized trials: STRESS and BENESTENT. These two trials—the former in the US, the latter in Europe—showed that stents placed in coronary arteries were better than conventional balloon angioplasty (PTCA) in maintaining vessel patency. The restenosis rates were 17-25% for stents while PTCA restenosis rates were 35%.
In 1995, when stents were first available for clinical use, stent implantation was fraught with two major problems:
1. Large doses of blood thinners were required, leading to unacceptably high rates of bleeding. Without these, stents quickly clot off, resulting in disastrous heart attacks!
2. Hospitalization periods were two to three times longer than with conventional PTCA. These limitations were overcome when it was discovered that Ticlid was far superior to Coumadin in preventing acute stent occlusion, with lower bleeding risks. Clopidogrel, a drug similar to Ticlid but with fewer side effects, replaced it. As a result, hospital stays shortened dramatically—now, patients typically stay only one day after an uncomplicated stent deployment, and acute stent occlusion is rare.
