Although the first coronary Wallstent implantation ushered in a new era in interventional cordiology with the purpose of circumventing the two major limitations of coronary balloon angioplasty, early acute occlusion and late restenosis, the previous investigators have reported a high rate of subacute occlusion after Wallstent implantation. However, recent studies have reported a low incidence rate of subacute closure and restenosis using the newly modified coronary Less Shortening in aortocoronary vein grafts. The present study reports the immediate results of the Less Shortening Wallstent Implantation for 21 diffuse native coronary lesions in 20 patients.

Twenty patients were enrolled at the Yonsei Univ. Cardiovasular Center of medical College, Yonsei University in Seoul, Korea from March 1996 through May 1996. The specific angiographic criteria for enrollment included at least 75% diameter stenosis, according to the estimate of two investigatior ; a lesion that was 20mm or more in lenght and a vessel diameter of at least 2.5mm. Bail-out procedure was performed in the case of abrupt closure or threatened closure, defined as a dissection and over 50% residual stenosis of the artery.

The coronary Less Shortening Wallstents were successfully implanted in the 21 diffuse coronary lesions(more than 20mm in length) of the 20 patients(pts), including 7 pts of acute myocardial infarction, 11 pts of unstable angina, and 2 pts of stable angina. Angiographic results after Less Shortening Wallstent were 3.0±0.3mm in minimal luminal diameter(MLD), 6.7±10.8% diameter stenosis(DS) comparing with pre-stent implantation MLD and DS, respectively, 0.3±0.4mm and 89.9±8.4%. During the in-hospital phase, no major cardiac event occurred except 2 cases of transmural myocardial infarction, including one of stent thrombosis and one of side branch occlusion, despite of inclusion of 7 cases of threatened occlusion in the long lesion. The peristent spasms were observed in 11 among 21 lesions, although long term significance of peristent spasm is not defined. The relative risk for peristent spasm were 10 times higher when larger stents(expanded stent diameter/reference artery diameter>1.7) were implanted. There was no peristent spasm when stents of which expanded stent diameter 1.4 times smaller than reference artery size ware used.

The results of this introductory study suggest that new Less Shortening Wallstent may reduce the requirement of multiple stent in the long lesion and a lower rate of thrombotic occusion in comparison to its prototype. Further large scale long term follow-up study is needed to evaluate the role of new Less Shortening Wallstent.