Quantitative angiographic follow-up of the coronary Wallstent in native vessels and bypass grafts (European experience - March 1986 to March 1990)

The coronary stent has been investigated as an adjunct to percutaneous transluminal coronary angioplasty to obviate the problems of early occlusion and late restenosis. From March 1986 to March 1990, 265 patients (308 lesions) were implanted with the coronary Wallstent^® in 6 European centers. For this study, the patients were analyzed according to date of implantation (group 1, March 1986 to January 1988; group 2, February 1988 to March 1990) and vessel type (native arteries versus bypass grafts). Quantitative angiographic follow-up was performed in 82% of the study patients. The early in-hospital occlusion rate in the overall group was 15%. Group 1 patients had a 20% rate in contrast to 12% rate in group 2 (p = not significant [NS]). The early occlusion rate in native vessels and bypass grafts was 19 and 8%, respectively (p = 0.019). Restenosis was determined by 2 criteria (criterion 1, ≥0.72 mm loss in minimal luminal diameter from poststent to follow-up; criterion 2, ≥50% diameter stenosis at follow-up) within the stent and in the segments immediately proximal and distal to the stent. The restenosis rate with criterion 1 was 43% in the overall group of patients, 35% in group 1 versus 49% in group 2 (p = NS), and 34% in native vessels versus 54% in bypass grafts (p = 0.016). The second criterion was met by 27% of patients in the overall group, 21% in group 1 versus 32% in group 2 (p = NS), and 18% in native vessel versus 39% in bypass grafts (p = 0.005). The overall mortality during the study period was 6.6% in native arteries and 9% in bypass grafts (6 and 7.9% at 1 year, respectively). The actuarial event-free survival (freedom from death, myocardial infarction, bypass surgery or angioplasty) for native artery patients was 46% at 40 months and for bypass graft patients 37% at 20 months. It is concluded that early in-hospital occlusions remain a major problem with this device despite improvement in the later experience. Although patients with bypass grafts had a significantly lower early occlusion rate than those with implantation of native arteries, a significantly higher rate of late restenosis limited the early benefits of stenting. The indications for stenting remain unknown and require results of randomized clinical studies.