Francis is in a stable condition in Birmingham Heartlands Hospital after undergoing surgery and could be well enough to return home within the next week.
A statement from the club on Saturday read: "Trevor Francis' family have contacted the club to express their sincere thanks for the overwhelming messages of support they have received from Blues fans in the last 24 hours.
"The Blues legend suffered a heart attack yesterday and underwent an operation at Heartlands Hospital.
"Thankfully the former striker and manager is recovering well and should be able to return home within the next week.
"Trevor's family have informed the club that he has been touched by the incredible amount of support that Bluenoses have shown since hearing the news that the 57-year-old had been taken ill.
"They have also expressed a big thank you to Heartlands Hospital."
I'm sure all Newcastle fans wish him well in his recovery.