Efficacy of coronary stenting versus balloon angioplasty in small coronary arteries. Stent Restenosis Study (STRESS) Investigators.

The goal of this study was to compare the efficacy of elective stent implantation and balloon angioplasty for new lesions in small coronary arteries. Palmaz-Schatz stents have been designed and approved by the Food and Drug Administration for use in coronary arteries with diameters > or = 3.0 mm. The efficacy of elective stent placement in smaller vessels has not been determined. By quantitative coronary angiography, 331 patients in the Stent Restenosis Study (STRESS) I-II were determined to have a reference vessel < 3.0 mm in diameter. Of these, 163 patients were randomly assigned to stenting (mean diameter 2.69 +/- 0.21 mm), and 168 patients were assigned to angioplasty (mean diameter 2.64 +/- 0.24 mm). The primary end point was restenosis, defined as > or = 50% diameter stenosis at 6-month follow-up angiography. Clinical event rates at 1 year were assessed. Baseline clinical and angiographic characteristics were similar in the two groups. Procedural success was achieved in 100% of patients assigned to stenting and in 92% of patients assigned to angioplasty (p < 0.001). Abrupt closure within 30 days occurred in 3.6% of patients in both groups. Compared with angioplasty, stenting conferred a significantly larger postprocedural lumen diameter (2.26 vs. 1.80 mm, p < 0.001) and a larger lumen at 6 months (1.54 vs. 1.27 mm, p < 0.001). Restenosis (> or = 50% diameter stenosis at follow-up) occurred in 34% of patients assigned to stenting and in 55% of patients assigned to angioplasty (p < 0.001). At 1 year, event-free survival was achieved in 78% of the stent group and in 67% of the angioplasty group (p = 0.019). These findings suggest that elective stent placement provides superior angiographic and clinical outcomes than balloon angioplasty in vessels slightly smaller than 3 mm.