Continued expansion of the nitinol self-expanding coronary stent: Angiographic analysis and 1-year clinical follow-up

Background: This study sought to report the first-year clinical outcome with the nitinol self-expanding coil stent and to provide angiographic data on the effect of self-expansion during implantation and follow-up. Self- expanding stents do not reach their nominal diameter at implantation. The long-term effects may therefore depend, in part, on continued expansion after initial implantation. Methods: Between January 1995 and January 1996, 86 stents were deployed in 64 patients for indication of suboptimal results. All patients were clinically followed up for 1 year, and 72% had follow-up angiography. Results: The majority (55%) of the lesions were class B2 or C. Balloon angioplasty increased the minimal lumen diameter from 1.07 ± 0.73 mm to 2.24 ± 0.57 mm; stent deployment further increased the diameter to 2.63 ± 0.48 mm, and within-stent balloon dilatation to 2.96 ± 0.62 mm. Angiographic follow-up performed at 7.8 ± 1.1 months (range 7-9 months) showed that the minimal lumen diameter was 2.15 ± 0.80 mm (late lumen loss of 0.81 ± 0.69 mm), and the mean stent diameter expanded to 3.58 ± 0.48 mm (self-expanding late stent gain of 0.62 ± 0.55 mm). The extent of this expansion was inversely related to the late lumen loss (r = 0.67, slope 0.81, P <.01). At 1 year 51 (80%) of 64 patients were event free; 3 had undergone coronary artery bypass grafting, 2 had a myocardial infarction, and 9 had repeat angioplasty. In the subgroup of a simple lesion (