The Food and Drug Administration said it saw a higher death rate after five years among patients treated for abdominal aortic aneurysms with Medtronic Inc.'s AneuRx stent-graft system than among those treated through conventional surgery. The FDA said it was focusing on the AneuRx stent-graft system because it is the only currently marketed device that has a significant number of patients who have been followed for at least five years after receiving a device.