United Airlines president and chief executive officer Oscar Munoz has undergone a heart transplant, an airline statement confirmed.

He is presently in recovery following the operation.

A transplant was considered the preferred treatment and was not the result of a setback in his recovery.

“The United team wishes Oscar well during his recovery, and expects him to return to United at the end of the first quarter or the beginning of the second quarter,” added a statement.

Additional information is expected in the next 24 hours.

United Airlines and United Express operate an average of nearly 5,000 flights a day to 352 airports across six continents.