The Food and Drug Administration has officially signed off on Entresto, a new drug that in a recent large clinical trial dramatically cut death rates from heart disease.

The approval resulted in a huge increase in shares for maker Novartis as the company expects to see sales of $5 billion annually from the drug, a rare prediction from a drug company that is calling this a “once-in-a-lifetime” discovery that could be a huge boon for heart disease patients around the world, according to a New York Times report.

If it were to achieve such sales, it would be one of the best-selling medications on the planet. The medical community has been excited about the drug after a clinical trial resulted in a 20 percent mortality rate reduction from cardiovascular diseases or heart failure hospitalizations.

About five million Americans, and 26 million people worldwide, are suffering from heart failure, which is when the heart has difficulty pumping the necessary blood to the body’s organs. This can results in high blood pressure or a heart attack, manifested by shortness of breath, fatigue, and retention of fluids, which often results in people seeking hospitalization.

Entresto was named LCZ696 during its development, and scientists believe it could replace what are known as angiotensin-converting enzym (ACE) inhibitors, which are currently used in the treatment of heart failure.

About 8,400 participants in the clinical trial were randomly assigned either Entresto or an ACE inhibitor known as enalapril. About 27 months later, 21.8 percent of those who took Entresto died or were hospitalized from heart failure, compared to 26.5 percent for enalapril. That’s a difference of 20 percent.

The main side effects for Entresto would be impairment of the kidney, low blood pressure, and high potassium levels.