Experiences of a quantitative coronary angiographic core laboratory in restenosis prevention trials

Abstract

Since its introduction more than 14 years ago [1], percutaneous transluminal coronary angioplasty (PTCA) has been attended by a 17% to 40% incidence of restenosis, typically developing within 6 months of the procedure [2–5]. Each year the number of patients undergoing PTCA has increased and now approaches the number treated with coronary artery bypass grafting (CABG). In the last 10 years, experimental models have given us more insight into the restenosis phenomenon and pharmacological agents have been developed aiming to prevent or reduce restenosis. Many of these agents have been investigated in clinical restenosis prevention trials [4–7] and although these agents were able to reduce restenosis in the animal model, most of the clinical trials failed to demonstrate a convincing reduction in the incidence of restenosis in man. In these clinical trials, the primary endpoint has been either angiographic (change in minimal luminal diameter at follow-up; >50% diameter stenosis at follow-up; loss >50% of the initial gain] and/or clinical [death; nonfatal myocardial infarction; coronary revascularization; recurrence of angina requiring medical therapy, exercise test, quality of life). The use of an angiographic parameter as a primary endpoint provides the necessary objectively whereby the patient population required for statistical analysis numbers between 500 and 700, whereas more than 2000 patients are necessary if a clinical endpoint is used [6].