The current status of stent placement in small coronary arteries < 3.0 mm in diameter

Data accrued to date indicate that stent placement in small vessels (< 3.0 mm reference diameter) suffers from the same disadvantage as other non-stent interventional devices in that the restenosis rate is significantly higher than observed following intervention involving large vessels. Randomized trials comparing systematic bare metal stenting versus conventional balloon angioplasty in the setting of small coronary arteries, however, show that the former therapeutic modality is probably superior to the latter treatment in its acute and mid-term angiographic and clinical results. Balloon angioplasty, even if performed optimally with resultant "stent-like" luminal outcome, yields a restenosis rate that is at best equivalent to that observed with stent placement. Stent performance is influenced profoundly by stent design and configuration. Tubular and corrugated stents are better than coil or meshwire stent design. Stents with thin struts appear to yield a lower restenosis rate compared with thick-strut stents. Coating the surface of stents with gold, phosphorylcholine or heparin does not appear to confer any additional long-term benefit compared with bare stainless-steel stents. On the other hand, impregnation of stents with anti-proliferative drugs, with or without a carrier polymer, has produced a significantly lower risk of restenosis, without an increase in stent thrombosis rate, compared with uncoated metal stents in multiple randomized trials. However, whether the clinico-anatomic benefits of drug-eluting stents can be sustained for several years and whether there are any long-term deleterious effects from the antiproliferative drug or carrier polymer remains unclear at this stage.