ORLANDO, Fla. (Reuters) - Pfizer Inc.'s top-selling cholesterol drug Lipitor can halt, not just slow, the potentially fatal buildup of plaque in clogged arteries, researchers said on Wednesday. The study is the first solid evidence that a prescription drug can stop the build-up of new plaque and even reverse it in some patients. A handful of drugs now available slow the buildup of new plaque, or atherosclerosis, in coronary arteries. "We were excited we could find a regimen, although an intensive one, that could stop the disease in its tracks," said the lead researcher, Dr. Steven Nissen of the Cleveland...