730-2 Acute Angiographic, Intravascular Ultrasound and Clinical Results of Directional Atherectomy in the Optimal Atherectomy Restenosis Study

The Optimal Atherectomy Restenosis Study (OARS) is a 200 patient multicenter (4 sites) registry designed to assess an intravascular ultrasound (IVUS) guided “optimal” directional atherectomy (DCA) on acute angiographic results, in-hospital complications, and late outcomes. At present, preliminary acute results are available for 155 lesions in 146 consecutively treated patients. Baseline patient characteristics were age 58 ± 11 years, male gender 74%, LAD treatment vessel 54%, CCVS angina class III or IV 75%, diabetes 15%, and prior PTCA 23%. Pre-treatment target lesions were 7.9 ± 2.6 mm in length, 63% were eccentric, 13% were ulcerated, and 20% had either moderate or severe calcification. Overall, procedure success (l 50% final stenosis without major complications) was achieved in 143 (98%) patients and there were in-hospital major complications in 3 (2.1%) patients including no deaths 10%). Q wave MI in 1 (0.7%), and emergency CABG in 2 (1.4%). Significant angiographic dissections ( ≥ grade C) after DCA were present in 9 (5.9%) patients and bailout stents were used to treat dissections in 4 (2.7%) without subsequent ischemic events. There was 1 perforation 10.7%) treated successfully with PTCA. Quantitative angiography was performed using an automated edge detection algorithm (CMS); reference diameter was 3.23 ± 0.48 mm and pre-treatment minimum lumen diameter (MLD) increased from 1.18 ± 0.44 mm to 2.74 ± 0.69 mm after DCA, and furtherto 3.14 ± 0.56 mm after adjunct PTCA (performed in 89% of treated lesions). Similarly, diameter stenosis was reduced from 63 ± 12% pre-treatment to 19 ± 19% after DCA to 7 ± 12% after adjunct PTCA. Sequential IVUS revealed an increase in lesion site cross-sectional area from 8.2 mm 2 following DCA to 9.0 mm 2 after adjunct PTCA (proximal reference area 10.5 mm 2 ). Despite the large final lumen dimensions (14% final cross-sectional area stenosis by IVUS). % cross-sectional narrowing (residual plaque burden) still averaged 57%. We conclude: (1) “optimal” DCA can be performed with high procedure success and few major in-hospital complications; (2) adjunct PTCA is usually required to achieve maximum lumen dimensions, and (3) despite these favorable angiographic results, IVUS reveals considerable residual plaque burden ( g 50%) after “optimal” DCA.