Balloon to artery ratio, not inflation pressure, correlates with adequate stent deployment: Size is more important than pressure

To investigate the relative importance of balloon to artery ratio (BAR) and poststent inflation pressure (IP), we retrospectively analyzed the 1VUS (intravascular ultrasound) data available for patients (n = 30) who underwent coronary stent implantations (n = 31) between May 1993 and April 1996 under various stent deployment strategies. Choice for sizing of the postdilatation balloon varied widely with BAR ranging from 0.75 to 1.34 (mean = 1.07 ± 0.14). IP also varied profoundly from 4 to 22 arm (mean = 14.7 ± 3.7 arms). Although there was no uncovered dissection or subintimal hemorrhage by IVUS, the adequacy of the stent deployment as assessed by relative stent expansion (RSE) varied significantly from 44.0% (very poor deployment) to 141.7% (overstretching of the arterial segment). Strikingly, BAR, not IP, correlated significantly with RSE (correlation coefficient [CC] of BAR = 0.77, P < 0.0001; CC of IP = 0.13, P > 0.5; stepwise linear regression analysis). No stent postdilated by a balloon with a BAR of ≤ 1.0 achieved a RSE of 100%, while BARs ≥ 1.2 uniformly resulted in RSEs ≥ 100%. In contrast, despite postdilation 1P of ≥ 15 atm, only 6 (33.3%) of 18 stents achieved RSE > 100%. Moreover, high RSEs were obtained by IP as low as 8 atms. Thus, BAR was much more strongly correlated with RSE, an index of optimal stent deployment, while IP was not correlated with RSE. These data suggest that BAR may be more important than IP for maximal stent implantation in the majority of patients. However, further larger scale, prospective studies are required to determine the importance of BAR versus IP to achieve optimal stent deployment.