Treating dialysis patients with the antiplatelet drug dipyridamole plus aspirin reduces blockages and extends the usefulness of new arteriovenous access grafts, reports a study in the May 21 New England Journal of Medicine. Stenosis and clotting often cause these grafts to fail, requiring costly procedures such as angioplasty to restore function. In a five-year study of 649 patients, the drug combination decreased arteriovenous graft failure by 18% compared with placebo, "a significant but clinically modest improvement," write the authors. Both groups experienced a 12% incidence of bleeding. The combination treatment costs $500 to $2,200 per patient per year.