Assessment of stent dimensions with a novel intracoronary balloon-based system: comparative study versus intravascular ultrasound and quantitative coronary angiography. The CAMUS - Coronary Angioplasty Metricath vs. UltraSound Trial.

Abstract

To compare measurements of coronary stent dimensions using a novel, low pressure balloon catheter-based technique - Metricath (MC), with those obtained by intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA). Intravascular ultrasound (IVUS), the current gold standard to optimize stent placement is expensive, not widely available, and needs expertise for interpretation. We compared cross-sectional diameter and area measurements obtained by MC, IVUS, and QCA immediately after successful stent implantation. The order of measurements was randomized. Both on-line and off-line (independent core lab) analysis was performed.Measurements were obtained in 21 patients at 22 stents in the LAD (n=10), RCA (n=6), and LCx (n=6). Nominal stent diameter was 2.5-3.5 mm. Average stent diameter was 2.54+/-0.28 mm by QCA, 2.77+/-0.31 mm by IVUS, and 2.86+/-0.28 mm by MC (P<0.001 QCA versus MC, P=0.13 IVUS versus MC). Results of on-line area measurements showed a small but significant difference between IVUS and MC 0.53 mm2, 95% confidence interval 0.17-0.90 mm2, P<0.01. Regression analysis demonstrated, however, that MC correlated best with off-line IVUS (diameter: y=1.01x, R2=0.83, P<0.001; area: y=1.02x, R2=0.81, P<0.001). Bland-Altman analysis showed a mean difference in diameter between on-line MC and off-line IVUS of 0.03+/-0.12 mm and between MC and off-line QCA of 0.10+/-0.23 mm. MC is a new, promising method providing information on average stent dimensions that is equivalent to that obtained by off-line IVUS analyzed in an independent core lab.