The first rigorous test of an expensive new drug that radically lowers cholesterol levels found that it significantly reduced the chance that a high-risk patient would have a heart attack or stroke. These were men and women who had exhausted all other options.

The results of the study, which cost about $1 billion and was paid for by Amgen, maker of the drug, were published on Friday in The New England Journal of Medicine and presented at the annual meeting of the American College of Cardiology.