Journal of Invasive Cardiology

Coronary angiography. Coronary angiography was performed through femoral or radial access over a conventional 0.014˝ guidewire after injection of 200 μg of nitroglycerin. All lesions were imaged from at least two orthogonal views. Selection of anticoagulation, other adjunctive pharmacotherapy, and percutaneous coronary intervention technique and equipment were at the discretion of the operator.

OCT procedure. FD-OCT was performed with the 2.7 Fr C7 Dragonfly Intravascular Imaging Catheter (St. Jude Medical) during intracoronary administration of contrast (Figure 2). All OCT cross-sectional images were initially screened for quality assessment and excluded from analysis if any portion of the image was out of the screen, a side branch occupied >45° of the cross-section, or the image had poor quality caused by residual blood, sew-up artifact, or reverberation. The catheter was advanced distally to the target lesion, and automated mechanical pullback performed at a speed of 20 mm/s during contrast injection until 54 mm were imaged. OCT analysis was performed with LightLab Imaging software (St. Jude Medical), with calibration before each measurement. Maximal and minimal lumen diameter and lumen cross-sectional area were measured at the minimal lumen site and proximal and distal reference points (defined as the nearest points without significant plaque proximal and distal to the target lesion) using semi-automatic lumen contour detection. The longitudinal distances from the proximal and distal reference points to the target lesion were also noted. The intra- and interobserver reproducibility of the FD-OCT measurements was excellent (correlation coefficients, 0.99 to 1.00).

IVUS procedure. IVUS was performed using a 20 MHz or 45 MHz imaging catheter (Volcano Corporation) starting distal to the target lesion and using a motorized transducer pullback system at a speed of 0.5 or 1.0 mm/s (Figure 1). IVUS images were analyzed offline using IVUS Enhancer software (Indec Medical Systems). Each target lesion detected on IVUS was matched to the OCT image using a combination of side branches, stent edges, stenoses, and other available landmarks. Maximum lumen diameter, minimum lumen diameter, and lumen cross-sectional area were measured at the minimal lumen site and at a proximal and distal reference site (defined as the points at equal longitudinal distance from the minimal lumen site as the reference points on OCT). IVUS measurements were performed in accordance with the American College of Cardiology Clinical Expert Consensus document on IVUS.¹ There was excellent intra- and interobserver reproducibility of the IVUS measurements (correlation coefficients, 0.93 to 1.00).