734-4 Can Intracoronary Ultrasound Improve PTCA Results?: Preliminary Core Lab Ultrasound Analysis from the CLOUT Pilot Study

The CLOUT Pilot Study hypothesis is that intracoronary ultrasound (ICUS) guidance can maximize the potential of balloon angioplasty through the safe application of carefully chosen oversized balloons. PTCA was performed until success was obtained using standard angiographic criteria. ICUS was then performed and, based on the degree of reference segment disease, balloons were upsized from 0.25 to 0.75mm (mean 0.4mm) regardless of the angiographic results. There have been no complications using this strategy in the initial 14 of a planned 100 patients. ICUS measures were performed using semiautomated programs at a core laboratory.ResultsIn the reference segment, ICUS revealed a mean lumen diameter of 2.60±0.35mm and plaque thickness of 0.78±0.11mm; on average 54.75±11.05% of the reference vessel was occupied by atheroma. At initial ICUS evaluation after angiographically successful PTCA, the lesion had a minimal lumen diameter (MLD) of 1.78±0.22mm and lumen area of 3.14±0.88mm2. Following balloon upsizing, the lesion MLD increased to 1.95±0.15mm (8.7% gain, p<0.02) and lumen area to 3.76±0.63mm2(16.7% gain, p<0.01). When compared to the reference segment lumen area, the lesional %lumen area reduction improved from 38.14±16.74% to 25.91±12.17% (p<0.01). Lumen improvement occurred primarily by expansion of the total vessel area (12.08±3.01mm2to 12.51±3.11 mm2, p=ns). As expected, there was a large degree of residual atheroma (68.62±7.47% cross sectional narrowing). After routine PTCA, only 5 of 12 patients reached a target MLD of 75% of the reference lumen diameter. Following balloon upsizing, 8 of 12 had reached this criteria.ConclusionsICUS guided balloon upsizing based on the degree of reference segment disease may be safely performed and results in significant improvement in luminal cross sectional area above that achieved by angiographic guidance alone. This may potentially lower restenosis rates if these initial gains are sustained long term