The planned trial enrolled 250 subjects per arm. Subjects are followed postoperatively and outcome endpoints will be assessed at Discharge, 6 Months, 1 Year, 3 Years, and 6 Years. One hundred (100) subjects will participate in neuropsychological testing at 1 Year; after the 100th subject an interim data analysis will be performed and the viability of future neuropsychological testing will be determined. Subjects will receive preoperative, intraoperative or postoperative, 3 Year follow up, and 6 Year follow up angiograms. In this fashion immediate clinical outcome, including peri-procedural morbidity and mortality, will be assessed as will long term outcome, both clinical and angiographic.