COMPARISON OF THE THROMBOGENICITY OF STAINLESS-STEEL AND TANTALUM CORONARY STENTS

This study was designed to compare the thrombogenicity of stainless st eel and tantalum coronary stents of the same design. Stainless steel a nd tantalum coronary stents are being evaluated for their utility in t reating acute closure and restenosis. A major disadvantage of stainles s steel stents is radiolucency. To determine whether radioopaque tanta lum stents may be safely substituted for stainless steel stents, we co mpared the relative thrombogenicity of these materials in stents of id entical design. Total platelet and fibrin deposition on the stents wer e determined from measurements of indium 111-labeled platelet and iodi ne 125-labeled fibrinogen accumulation after deployment into exteriori zed chronic arteriovenous shunts in seven untreated baboons. In anothe r series of experiments, (111)ln-platelet deposition was compared 2 ho urs after stent implantation in coronary arteries of pigs. In baboons, platelet thrombus formation on stainless steel and tantalum stents wa s equivalent and plateaued at approximately 2.5 X 10(9) platelets afte r 1 hour (p > 0.05). Fibrin deposition averaged approximately 1 mg/ste nt and did not differ between the stainless steel and tantalum stents (p > 0.05). In the porcine coronary model there was no significant dif ference in (111)ln-labeled platelet deposition between the stainless s teel and tantalum stents (p > 0.05). This result was confirmed by scan ning electron microscopic analysis of the coronary stents. Based on th ese two models, we conclude that there is no significant difference in the thrombogenicity of stainless steel and tantalum wire coil stents.