Luminal loss and site of restenosis after Palmaz-Schatz coronary stent implantation.

Restenosis has frequently been observed at the articulation of the Palmaz-Schatz stent. However, the precise mechanism for this remains poorly understood. We measured the luminal diameter in 5 segments within the stent in 67 lesions of 63 patients with successful stenting. Luminal diameter at all 5 sites was significantly reduced 6 months after stent implantation (3.2 +/- 0.5 vs 2.4 +/- 0.7 mm, p < 0.05). Angiographic restenosis rate was 18%. Restenosis involving the articulation was found in 75% of the lesions, and that involving the articulation or edges in 83%. The diameter at the articulation was significantly smaller both immediately (3.0 +/- 0.5 mm vs 3.3 +/- 0.5 mm, p < 0.05) and 6 months after (2.1 +/- 0.8 mm vs 2.5 +/- 0.7 mm, p < 0.05) stenting than the diameter of other stent segments. The loss index was significantly greater at the proximal and distal edges than at the bodies of the stent (0.98 vs 0.60, p < 0.05). The edges of the Palmaz-Schatz stent tend to dilate more than the body of the stent during normal inflation. Although this anchoring system protects against dislodgment or migration of the stent, it may cause more injury. The articulation has 2 anchoring edges within only a 1 mm diameter. Thus, restenosis at the articulation may be ascribed to residual stenosis, increased intimal proliferation due to more severe injury, and delayed late vessel remodeling from lack of mechanical support. These characteristics may be attributed to stent design, and design improvement of the articulation may lead to more favorable results after stent implantation.