Although Henry was not seen by reporters on Wednesday, Professional Footballers' Association official Bobby Barnes said the French striker had visited the hospital and Muamba.
The 23-year-old Muamba remains in intensive care after collapsing during Saturday's FA Cup quarterfinal at Tottenham. It took 78 minutes for Muamba's heart to start beating again on its own, doctors said.
By Monday, Muamba was breathing independently and talking.
Henry was at Arsenal when Muamba went from the academy in 2002 to the first team in 2005. The midfielder left two years later for Birmingham before joining Bolton.