Prospective evaluation of the impact of side-holes and guide catheter disengagement from the coronary ostium on fractional flow reserve measurements

Background. We prospectively examined the impact of side-holes and guide-catheter disengagement on fractional flow reserve (FFR) measurements. Methods. Twenty-five patients undergoing clinically indicated FFR measurement for intermediate coronary artery stenosis were enrolled. Four FFR measurements were made in random order during intravenous adenosine infusion with: (a) an engaged side-hole guide catheter; (b) a disengaged side-hole guide catheter; (c) an engaged non-side-hole guide catheter; and (d) disengaged non-side-hole guide catheter. Results. Mean patient age was 65 +/- 9 years and 100% were men. The mean distal poststenotic pressure/proximal aortic pressure (P-d/P-a) at baseline was 0.93 +/- 0.05 mm Hg. Using intravenous adenosine infusion, the mean FFR measured with engaged vs disengaged non-side-hole guide catheters was 0.87 +/- 0.09 vs 0.83 +/- 0.10, respectively (mean difference, 0.039 +/- 0.04; P<. 001). The mean FFR with engaged vs disengaged side-hole guide catheters was 0.85 +/- 0.10 vs 0.83 +/- 0.10 (mean difference, 0.020 +/- 0.02; P<. 001). The mean difference in FFR measurements was 0.024 +/- 0.03 (P<. 001) among engaged guide catheters and 0.005 +/- 0.03 (P=. 47) among disengaged guide catheters. Conclusions. When FFR measurements are performed with engaged guide catheters, side-hole catheters provide lower measurements. When FFR measurements are obtained with disengaged guide catheters, they are even lower and similar between guide catheter types.