"The manager will resume his duties with the team in the coming days," said the statement.
The club said the 66-year-old coach had been suffering from an irregular heartbeat.
Sarri returned to the Rome club this summer following the resignation of Marco Baroni.
Sarri was Lazio's manager between 2021 and March 2024 and led the club to second place in Serie A in 2023.
Sarri, a heavy smoker, worked as a banker before quitting to become a full-time coach.
He took Empoli to promotion to Serie A in 2014. He then guided his hometown club Napoli to two second-place Serie A finishes, led Chelsea to the Europa League in 2019, and Juventus to the Serie A title in 2020.
Lazio are eighth in Serie A with 24 points from 17 games. They host third-placed Napoli on Sunday.