Drug eluting stents in the infrainguinal circulation

The short-term efficacy of drug-eluting stents has been validated in the coronary circulation, particularly with the drugs rapamycin and paclitaxel. The physical environment of the infrainguinal arteries is very different from the coronary circulation. Self-expanding stents are necessary in the femoropopliteal segment, which is subject to recurrent external forces. These include flexion at the knee, compression within the adductor hiatus, rotation and longitudinal compression. Thus, the properties required of a drug coating is likely be very different from those used in coronary arteries. This would appear to be borne out by SIROCCO, the only published study to date evaluating drug-eluting stents in the noncoronary circulation. SIROCCO began as a prospective randomized 36 patient trial comparing rapamycin coated to uncoated self-expanding SMART stents in the femoropopliteal segment. The first phase of SIROCCO demonstrated reduction of intimal hyperplasia by rapamycin. However, the study is being repeated to optimize the rate of drug elution, and multiple stent fractures seen in the first phase of the study necessitated modification of stent design. Considerable further study of drug eluting stents will be required in each vascular bed to determine the ideal stent/drug combination, and to establish clinical efficacy.