The Current Status of Stent Placement in Small Coronary Arteries
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.
Stent placement in coronary arteries ≥ 3.0 mm in diameter has been irrefutably proven to be superior to conventional balloon angioplasty (PTCA) in reducing the risk of restenosis and major adverse cardiac events. Subsequent improvements in stenting technique and antithrombotic regimen have dramatically reduced the incidence of stent thrombosis. These favorable outcomes in concert have resulted in an exponential rise in the volume of stent-related procedures and have extensively broadened the indications for stenting to encompass non-STRESS/BENESTENT lesions, including, among others, lesions in small coronary arteries (< 3.0 mm in diameter). It is estimated that 30-50% of all percutaneous coronary interventions involve small vessels. The concept of stent placement in small vessels is attractive and has far-reaching clinical and cost implications, particularly in patients with a high preponderance of small coronary arteries, such as women, diabetics and Indo-Asians. It is highly effective in rectifying acute or threatened closure and affords significantly better acute luminal gain than other catheter-based devices. Therefore, it may theoretically reduce the risk of restenosis in accordance with the prevailing "bigger is better" paradigm that predicts a better late angiographic and clinical outcome with larger acute luminal gains. Despite this favorable finding, it remains controversial whether stent placement is actually superior to PTCA in a small vessel setting. This article aims to provide an update on the current status, review the major trials and define the clinical utility of small vessel stenting (SVS), particularly in the era of drug-eluting stents (DES).
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.
Stent placement in coronary arteries ≥ 3.0 mm in diameter has been irrefutably proven to be superior to conventional balloon angioplasty (PTCA) in reducing the risk of restenosis and major adverse cardiac events. Subsequent improvements in stenting technique and antithrombotic regimen have dramatically reduced the incidence of stent thrombosis. These favorable outcomes in concert have resulted in an exponential rise in the volume of stent-related procedures and have extensively broadened the indications for stenting to encompass non-STRESS/BENESTENT lesions, including, among others, lesions in small coronary arteries (< 3.0 mm in diameter). It is estimated that 30-50% of all percutaneous coronary interventions involve small vessels. The concept of stent placement in small vessels is attractive and has far-reaching clinical and cost implications, particularly in patients with a high preponderance of small coronary arteries, such as women, diabetics and Indo-Asians. It is highly effective in rectifying acute or threatened closure and affords significantly better acute luminal gain than other catheter-based devices. Therefore, it may theoretically reduce the risk of restenosis in accordance with the prevailing "bigger is better" paradigm that predicts a better late angiographic and clinical outcome with larger acute luminal gains. Despite this favorable finding, it remains controversial whether stent placement is actually superior to PTCA in a small vessel setting. This article aims to provide an update on the current status, review the major trials and define the clinical utility of small vessel stenting (SVS), particularly in the era of drug-eluting stents (DES).