Functional assessment of jailed side branches in coronary bifurcation lesions using fractional flow reserve

Abstract

Objectives: This study was designed to assess the functional significance of side branches after stent implantation in main vessels using fractional flow reserve (FFR).

Background: Little is known about the functional significance of side branches after stent implantation in main vessels in coronary bifurcation lesions.

Methods: Between May 2007 and January 2011, 230 side branches in 230 patients after stent implantation in main vessels were assessed by FFR and were consecutively enrolled.

Results: Median FFR at the side branch was 0.91 (interquartile range: 0.85 to 0.95). There was a negative correlation between the diameter stenosis (DS) by quantitative coronary angiography (QCA) and FFR of side branch (r=-0.21, p=0.002), but only 41 (17.8%) side branches were functionally significant after stent implantation in the main vessel. Among 67 side branches with >50% DS by QCA, 19 (28.4%) had FFR≤0.80, and among 163 side branches with ≤50% DS by QCA, 22 (13.5%) had FFR≤0.80 after stent implantation in main vessels. On the basis of receiver-operating characteristic curves, the optimal cutoff value of DS by QCA of the side branch was 54.9%, and the area under the curve was 0.64 (95% confidence interval [CI]: 0.58 to 0.71, p<0.001) with a 41.5% sensitivity, an 83.1% specificity, a 34.7% positive predictive value, an 86.3% negative predictive value, and a 75.7% accuracy. Multivariate binary logistic regression analysis identified DS by QCA (odds ratio [OR]: 1.04, 95% CI: 1.02 to 1.06, p=0.001) and reference vessel diameter (OR: 0.28, 95% CI: 0.10 to 0.77, p=0.014) before stent implantation as independent predictors of the side branches with FFR≤0.80 after stent implantation.

Conclusions: Most side branch lesions do not have functional significance after stent implantation in the main vessel, and quantitative coronary angiography is unreliable in assessing the functional severity of these lesions.