Opticross

Intravascular ultrasound was performed using an intracoronary imaging system (Opticross, Boston Scientific, Marlborough, MA, USA) operating with a transducer frequency of 40 MHz. A 0.018-in. diameter coronary guidewire (Hi-Torque Balance Middleweight, Abbott Cardiovascular, MN, USA) was passed through the water-filled phantom and fixed at either end. The imaging catheter was then loaded onto the coronary guidewire and positioned in the region of an iliac vessel. Images were acquired with an automated pullback speed of 1 mm/s.

Quantitative coronary angiography (QCA) analysis was performed using computer-based software (HeartII ver2.0.2.3, GADELIUS) before the procedure, after the procedure, and at follow-up by an independent physician who was blinded to patient and procedural characteristics. Optimal views of the lesions were obtained at baseline, and the same projection angle was used at follow-up. The minimal lumen diameter (MLD), reference diameter (RD), lesion length, and percent diameter stenosis (%DS) were measured. The acute gain was defined as the increase in MLD after PCI; late lumen loss was defined as the difference between the postprocedural MLD and the MLD at follow-up. Binary restenosis was defined as %DS >50% at follow-up. All IVUS procedures were performed using commercially available IVUS catheters (OptiCross™; Boston Scientific, or ViewIT®; Terumo) with automatic pull-back at a rate of 0.5 mm/s. At the narrowest cross-section area, lumen diameter, lumen area, vessel area, and %PA were analyzed. The %PA was defined as (vessel area-lumen area) × 100/vessel area. The incidence of hematoma, intimal dissection, and medial dissection was recorded. The IVUS images were analyzed using computerized planimetry software (echoPlaque; INDEC Medical Systems, Los Altos, CA, USA). All images were independently assessed by physicians who were blinded to patient and clinical data.

Before procedural, all patients received an oral loading dose of 300 mg aspirin and 300 mg clopidogrel. During procedural, all patients received unfractionated heparin at a dose of 70–100 U/kg to maintain an activated clotting time (ACT) > 300 s. In both groups, the choice of vascular access, burr size, IVUS/OCT was left at the operators’ discretion. The IVUS/OCT catheter was advanced beyond the target lesion using a commercially available IVUS/OCT system (40 MHz IVUS catheter; OptiCross, Boston Scientific. ILUMIEN C7-XR, Abbott). RA was performed by using the Rotablator (Boston Scientific Scimed, Inc., Maple Grove, MN, USA). The burr size was selected to reach a burr/vessel ratio of 0.5–0.6. RA speed ranged between 150,000 and 180,000 rotation per minute. Each RA time was 10–15 s. During RA, A continuous intracoronary infusion of a cocktail with unfractionated heparin and nitroglycerin was employed. Success of RA was defined as complete expansion of balloon of target lesion after RA.

Quantitative analysis was done by an experienced cardiologist. Quantitative angiography analysis was performed by standard techniques with automated edge-detection algorithms (CASS-5.2, Pie Medical, Maastricht, the Netherlands). IVUS imaging was performed after intracoronary administration of 0.2 mg nitroglycerin, using motorized transducer pullback (0.5 mm/s) and a commercial scanner (OptiCross, Boston Scientific, MA, USA). The IVUS data were stored on DVD, and quantitative IVUS analysis (EchoPlaque 3.0, Indec Systems, MountainView, CA, USA) was performed off-line by a single experienced investigator.