Is adjunctive balloon postdilatation necessary after coronary stent deployment? Final results from the POSTIT trial

Early-generation balloon-expandable stents required postdilatation with noncompliant balloons at high pressure to optimize stent deployment. The need for adjunctive balloon postdilatation with modern stent delivery systems is unknown. Patients undergoing elective stenting were randomized to Boston Scientific NIR, Guidant Tri-Star/Tetra, and Medtronic AVE S670 stents. The primary endpoint was optimum stent deployment defined as a minimal stent diameter (MSD) ≥ 90% of the average reference lumen diameter assessed by intravascular ultrasound (IVUS) performed immediately following stent deployment. If, by operator assessment, the primary endpoint was not achieved with the stent delivery system, adjunctive postdilatation with noncompliant balloons was performed. Of 256 patients with IVUS studies adequate for core laboratory analysis, only 29% achieved optimum stent deployment with the stent delivery system. None of the baseline clinical or angiographic variables predicted optimum stent deployment. Of the procedural variables, the type of stent and nominal stent size were not predictors, but higher deployment pressures were associated with a higher frequency of optimum stent deployment (< 12 atm 14% vs. ≥ 12 atm 36%; P = 0.007). The inability to achieve optimum stent deployment was not due to undersizing the stent delivery balloon, but rather to an inability of the stent delivery balloon to expand fully the stent to nominal size. In patients who underwent postdilatation, the frequency of achieving optimum stent deployment increased from 21% to 42%, minimal stent area increased from 6.6 ± 2.2 to 7.8 ± 2.3 mm², and MSD increased from 2.6 ± 0.5 to 2.8 ± 0.4 mm. These data stress the continued need for adjunctive balloon postdilatation with modern stent delivery systems. Cathet Cardiovasc Intervent 2003;59:184–192. © 2003 Wiley-Liss, Inc.