Improved procedural results of coronary angioplasty with intravascular ultrasound-guided balloon sizing - The CLOUT pilot trial

Background Indiscriminate use of balloons larger than the angiographic reference segment lumen results in high rates of ischemic complications after percutaneous transluminal coronary angioplasty (PTCA). We hypothesized that angiographically unsuspected atheromatous remodeling with vessel expansion (the Glagov phenomenon) at and adjacent to PTCA target lesions would safely accommodate oversized balloons in selected patients undergoing PTCA with intravascular ultrasound (IVUS) guidance. Methods and Results After angiographically guided PTCA of 104 lesions in 102 patients, IVUS was performed, and if atheromatous remodeling was present, PTCA was repeated with larger balloons sized halfway between the lumen and external elastic membrane. Plaque occupied a mean of 51+/-15% of the angiographically ''normal'' reference segments. Further balloon upsizing by 0.25 to 1.25 mm was therefore performed in 76 lesions (73%), increasing the nominal balloon-to-artery ratio from 1.12+/-0.15 after standard PTCA to 1.30+/-0.11 after IVUS-guided PTCA (P<.0001). As a result, the angiographic minimal luminal diameter further increased from 1.95+/-0.49 to 2.21+/-0.47 mm, the % diameter stenosis fell from 28+/-15% to 18+/-14%, and the IVUS lumen area rose from 3.16+/-1.04 to 4.52+/-1.14 mm(2) (all P<.0001). The incidence of angiographic dissection was not increased after IVUS-guided balloon upsizing (37% versus 40%, P=.67), and major complications occurred in only 2 patients (1.9%). Conclusions The demonstration by IVUS of atheromatous remodeling permits the safe use of balloons traditionally considered oversized, resulting in significantly improved luminal dimensions without increased rates of dissection or ischemic complications.