Anti-restenosis Trials.

The high frequency of restenosis after percutaneous coronary angioplasty is still a major clinical problem. It occurs in 30% to 60% of patients and limits the long-term success of angioplasty. Many clinical trials have been conducted to resolve this problem, using a wide range of pharmacologic agents such as antiplatelet agents, anticoagulation drugs, lipid-lowering drugs, angiotensin-converting enzyme inhibitors, anti-inflammatory drugs, and antiproliferative drugs. Thus far, no effective drug has been reported, with the exception of probucol, which unfortunately is not approved by the US Food and Drug Administration because it prolongs the QT time, and possibly trapidil and cilostazol, two agents that are currently being tested in larger trials. Stent implantation has significantly reduced the frequency of restenosis in patients with 1) short lesions in large coronary arteries, (> 3.0 mm), 2) native coronary restenosis lesions, 3) venous bypass graft obstructions, 4) chronic total occlusions, and 5) acute myocardial infarction in patients referred for primary percutaneous intervention. A significant problem is the occurrence of in-stent restenosis because it is associated with a high recurrence of restenosis, after repeat coronary intervention irrespective of the technique or device used. Brachytherapy may limit this problem. The high restenosis rate occurring in long lesions and in small vessels still remains an unresolved issue.