Some Wall Street analysts predict the drug, a tablet taken twice a day, will achieve billions of dollars in annual sales. Seamus Fernandez, an analyst at Leerink Partners, said on Saturday that the results were “near best case” and “could result in faster uptake, higher penetration and more robust branded pricing.”

As a proprietary drug, LCZ696 is likely to be expensive. Tim Anderson, an analyst at Sanford C. Bernstein & Company, estimates that it might cost $7 a day in the United States, or about $2,500 a year. Existing drugs are generic, costing as little as $4 a month, so insurers might balk at paying for the new drug.

David Epstein, the head of Novartis’s pharmaceutical division, said the company could make a good case to payers. “It’s very rare that a drug like this comes along,” he said, “one where people live longer, have less hospitalizations and other costs and feel better.”

The study, sponsored by Novartis, involved more than 8,400 patients in 47 countries who were randomized to receive either LCZ696 or enalapril, one of a class of drugs called ACE inhibitors that have been the standard treatment for heart failure. Most patients also used beta blockers and other drugs, as their doctors saw fit.

The patients were followed for a median of 27 months. By that point, 21.8 percent of those who received LCZ696 had died from a cardiovascular cause or had been hospitalized for worsening heart failure. That figure was 26.5 percent for those receiving enalapril. That represents a 20 percent relative reduction in risk using a statistical measure called the hazard ratio.

The reductions in risk for both cardiovascular death alone and hospitalization alone were also about 20 percent. About 32 patients had to be treated with LCZ696 to prevent one death from cardiovascular causes.

LCZ696 was relatively well tolerated, though patients who clearly could not tolerate the specified doses of either LCZ696 or enalapril were eliminated from the trial in advance. LCZ696 caused more hypotension, or too-low blood pressure, but fewer kidney problems than enalapril.